The Ministry of Consumer Affairs, Food & Public Distribution has released draft rules under the Legal Metrology (General) Amendment Rules, 2024, con-cerning Automatic Catch Weighing Instruments. These rules aim to regulate devices used for weighing discrete or loose materials, such as checkweighers, vehicle-mounted instruments, and weigh-price labelers. Detailed provisions outline construction, terminology, and metrolog-ical requirements for these instruments. Stakeholders, including State Legal Metrology De-partments, industry representatives, and associations, are invited to review and provide comments by January 8, 2025. Submissions can be made via email to [email protected] or [email protected]. The draft rules, set to come into effect on July 1, 2025, are available on the Department’s official website for reference.
I-9/10/2024-W&M
Government of India
Ministry of Consumer Affairs, Food & Public Distribution
Department of Consumer Affairs
Legal Metrology Division
Krishi Bhawan, New Delhi-01
Dated: 09.12.2024
Subject– Draft Rules for Automatic Catch Weighing Instruments comments from stakeholders – reg.
Undersigned is directed to refer to the above mentioned subject and to state that the Draft Rules for Automatic Catch Weighing Instruments are placed in the website of the Department www.consumeraffairs.nic.in for seeking comments from all stakeholders by 08.01.2025. The comments may be sent to email-ID: [email protected]/ [email protected].
Sd/-
(Ashutosh Agarwal)
Director (Legal Metrology)
Ph: 011-23389489
Email: [email protected]
To:
All concerned (State Legal Metrology Departments, VCOs, Industries and Industry Associa-tions)
[TO BE PUBLISHED IN THE GAZETTE OF INDIA, EXTRAORDI-NARY, PART II SECTION 3,
SUB-SECTION (i)]
GOVERNMENT OF INDIA
MINISTRY OF CONSUMER AFFAIRS, FOODAND PUBLIC DISTRIBUTION
(DEPARTMENT OF CONSUMER AFFAIRS)
NOTIFICATION
New Delhi, the ……………………… 2024.
GSR…………… In exercise of the powers conferred by sub-section (1) read with clauses (c), (f), (h), (i) and (s) of sub-section (2) of section 52 of the Legal Metrology Act 2009, (1 of 2010), the Central Government hereby makes the following rules, namely:
1. Short title and commencement.- (1) These rules shall be called the Legal Metrology (Gen-eral) Amendment Rules, 2024
(2) They shall come into force on 1st day of July, 2025.
2. In the Legal Metrology (General) Rules, 2011,-
(1) in the index of the Schedule of the Legal Metrology (Gen-eral) Rules, 2011, in Seventh Schedule, after Heading F, the following heading shall be insert-ed, namely:–
“Heading G, Automatic catch weighing in-struments”;
(2) in the “Seventh Schedule, after “Heading F” and the entries relating thereto, the following Heading and entries shall be inserted, namely:-
“Heading G
Automatic Catch weighing instruments
Part I
TERMINOLOGY
1. General Definition
(1) Weighing instrument
Measuring instrument that serves to determine the mass of an amount of material by using the action of gravity on this material.
“mass” (or “weight value”) is preferably used in the sense of “Conventional mass” or “conventional value of the result of weighing in air” The instrument shall also be used to determine other quantities, magnitudes, parameters or characteristics related to mass. According to its method of operation, a weighing instrument is classified as automatic or nonautomatic.
(2) Automatic weighing instrument
Instrument that weighs and follows a pre-determined program of automatic processes characteristic of the instrument.
(3) Automatic catch weighing instrument (catchweigher)
Automatic weighing instrument that weighs pre-assembled discrete loads or single loads of loose material.
(i) Checkweigher
Catchweigher that sub-divides prepackages of different mass into two or more sub-groups according to the value of the difference between their mass and the nominal set point.
(ii) Weigh labeler
Catchweigher that labels individual pre-assembled discrete loads (e.g. prepackages) with the weight value.
(iii) Weigh-price labeler
Catchweigher that calculates the price to pay on the basis of the indicated mass and the unit sale price and labels individual pre-assembled discrete loads (e.g. prepackages with the weight value, unit sale price and retail sale price to pay).
(iv) Vehicle mounted instrument
Complete instrument that is firmly mounted on a vehicle and that is designed for that special purpose.
Note: For example, a garbage weigher (waste col-lecting vehicle) that determines the quantity of loose material emptied from a container (sup-ported by the load receptor) into the body of the vehicle.
(v) Vehicle incorporated instrument
Instrument where components of the vehicle which are also components of the weighing instrument, i.e. parts of the vehicle (levers, joints and/or force transmission) are used for the instrument.
Note: For example, a front-end loader (front-end loading vehicle) that determines the quantity of loose material held in the bucket (load recep-tor).
(4) Loose material
Material which is not packaged during and/or after the weighing process. The material shall be collected for weighing in the load receptor of the instrument (e.g. front-end loader) or in a separate container (garbage weigher).
(5) Grading instrument
Instrument which assigns a weighing result to a predetermined range of mass to determine a tariff or toll.
Examples: postal scales, garbage weighers.
(6) Electronic instrument
Instrument equipped with electronic devices.
(7) Control instrument
Weighing instrument used to determine the conventional true value of the mass of the test load(s).
Control instruments used for testing shall be:
(i) separate from the instrument being tested; or
(ii) integral, when a static weighing mode is provided by the in-strument being tested.
(8) Conventional true value (of a quantity)
Value attributed to a particular quantity (mass of a body) and accepted, by convention, as having an uncertainty appropriate for a given purpose.
(9) Indication of an instrument
Value of a quantity provided by a measuring instrument.
Note: The terms “indication”, “indicate” or “indi-cating” include both displaying and/or printing.
(i) Primary indications
Indications, signals and symbols that are subject to the re-quirements of this specification.
(ii) Secondary indications
Indications, signals and symbols that are not primary indica-tions.
(10) Metrologically relevant
Any device, module, part, component, function or software of a weighing instrument that influences the weighing result or any other primary indication is con-sidered as metrologically relevant.
2. Construction
(1) Load receptor
Part of the instrument intended to receive the load.
(2) Load-transmitting device
Part of the instrument for transmitting the force produced by the load acting on the load receptor to the load-measuring device.
(3) Load-measuring device
Part of the instrument for measuring the mass of the load by means of an equilibrium device for balancing the force coming from the load transmitting de-vice, and an indicating device.
(4) Load conveyor
Device to move the loads on to and off the load receptor.
(5) Load transport system
System used to transport the load over the load receptor.
(6) Displaying device (of a weighing instrument) Device provid-ing the weighing result in visual form.
(7) Module
Identifiable part of an instrument that performs a specific func-tion or functions, and that shall be separately evaluated according to the metrological and technical performance requirements in the specification. The modules of a weighing instru-ment are subject to specified partial error limits. Typical modules of an automatic weighing instrument are: load cell, indicator, analog or digital data processing device, computer termi-nal, weighing module, digital display.
(i) Load cell
Force transducer which, after taking into account the effects of the acceleration of gravity and air buoyancy at the location of its use, measures mass by con-verting the measured quantity (mass) into another measured quantity (output).
(ii) Indicator
Electronic device of an instrument that shall perform the ana-log-to-digital conversion of the output signal of the load cell, and which further processes the data, and displays the weighing result in units of mass.
(iii) Analog data processing device
Electronic device of an instrument that performs the analog-to-digital conversion of the output signal of the load cell, further processes the data, and supplies the weighing result in a digital format via a digital interface without displaying it. It shall op-tionally have one or more keys (or mouse, touchscreen, etc.) to operate the instrument.
(iv) Digital data processing device
Electronic device of an instrument that further processes the data, and supplies the weighing result in a digital format via a digital interface without display-ing it. It shall optionally have one or more keys (or mouse, touch-screen, etc.) to operate the instrument.
(v) Weighing module
Part of the weighing instrument that comprises all mechanical and electronic devices (i.e. load receptor, load-transmitting device, load cell, and analog data processing device) but not having the means to display the weighing result. It shall optionally have devices for further processing (digital) data and operating the instrument.
(vi) Computer terminal
Digital device that has one or more keys (or mouse, touch-screen, etc.) to operate the instrument, and a display to provide the weighing results transmit-ted via the digital interface of a weighing module or an analog data processing device.
(vii) Digital display
Either incorporated in the indicator housing or in the computer terminal housing or realized as a display in a separate housing (i.e. terminal without keys), e.g. for use in combination with a weighing module.
(viii) Software
(a) parameter
Parameter that belongs to the measuring instrument or device, and defines or fulfils functions which are subject to control.
The following types of parameter shall be distinguished: type-specific and device specific.
(b) Type-specific parameter
parameter with a value that depends on the type of instrument only. Type-specific parameters are part of the software. They are fixed at model approval of the instrument.
Examples of type-specific parameters are: parameters used for mass calculation, stability analysis or price calculation and rounding, software identifica-tion.
(c) Device-specific parameter
parameter with a value that depends on the individual instru-ment. Such parameters comprise calibration parameters (e.g. span adjustments or correc-tions) and configuration parameters (e.g. maximum capacity, minimum capacity, units of measurement, etc.). They are adjustable or selectable only in a special operational mode of the instrument. They shall be classified as those that shall be secured (unalterable) and those that shall be accessed (settable parameters) by an authorized person.
(d) Software identification
Sequence of readable characters of software, inextricably linked to the software (e.g. version number, checksum).
(e) Data storage device
Internal memory storage of the instrument or external (remov-able) storage device used for keeping measurement data ready after completion of the meas-urement.
(f) Software separation
Unambiguous separation of software into relevant software and non-relevant software.
If no software separation exists, the whole software is to be considered as legally relevant.
(8) Electronic parts
(i) Electronic device
Device employing electronic sub-assemblies and performing a specific function.
Electronic devices are usually manufactured as separate units and are capable of being tested independently.
An electronic device, as defined above, shall be a complete instrument (e.g. an instrument for direct sales to the public), a module (e.g. indicator, analog data processing device, weighing module) or a peripheral device (e.g. printer, secondary dis-play).
(ii) Electronic sub-assembly
Part of an electronic device, employing electronic components and having a recognizable function of its own.
Examples: A/D converter, display.
(iii) Electronic component
Smallest physical entity that uses electron or hole conduction in semi-conductors, gases or in a vacuum.
Examples: Electronic tube, transistor, integrated circuit.
(9) Indicating device (of a weighing instrument)
Part of the load-measuring device that displays the value of a weighing result in units of mass and shall additionally display:
the difference between the mass of an article and a reference value;
the mean value and/or the standard deviation of a number of consecutive weighings.
(i) Indicating device with a differentiated scale division
Digital indicating device of which the last figure after the dec-imal sign is clearly differentiated from the other figures.
(ii)Extended indicating device
Device that temporarily changes the actual scale interval, d, to a value less than the verification interval, e, following a manual command.
(10) Supplementary device
(i) Setting device
Device for fixing the limits of mass of the sub-groups.
(ii) Nominal set point
Value expressed in units of mass preset by the operator by means of the setting device in order to establish the limit between consecutive sub-groups.
(iii) Adjustment range
Range of weight values close to a set point outside which the weighing results shall be subject to excessive relative error.
(iv) Counter
Device counting the number of loads which have moved on to the load receptor (movement counter) or indicating the number of the loads in each of the sub-groups (division counter).
(v) Sorting device
Device which automatically divides the loads into separate sub-groups.
(vi) Leveling device
Device for setting an instrument to its reference position.
(vii) Tilt limiting device
Device which prevents the instrument from operating above a predetermined value of tilt.
(viii) Zero-setting device
Device for setting the indication to zero when there is no load on the load receptor.
(a) Non-automatic zero-setting device
Device for setting the indication to zero by an operator.
(b) Semi-automatic zero-setting device
Device for setting the indication to zero automatically following a manual command.
(c) Automatic zero-setting device
Device for setting the indication to zero automatically without the intervention of an operator.
(d) Initial zero-setting device
Device for setting the indication to zero automatically at the time the instrument is switched on and before it is ready for use.
(ix) Zero-tracking device
Device for maintaining the zero indication within certain limits automatically.
(x) Tare device
Device for setting the indication to zero when a load is on the load receptor:
(a) without altering the weighing range for net loads (additive tare device); or
(b) reducing the weighing range for net loads (subtractive tare device). It shall function as:
(c) a non-automatic device (load balanced by operator);
(d) a semi-automatic device (load balanced automatically fol-lowing a single manual command);
(e) an automatic device (load balanced automatically without the intervention of an operator).
(xi) Tare balancing device
Tare device without indication of the tare value when the in-strument is loaded.
(xii) Tare-weighing device
Tare device that stores the tare value and is capable of indicat-ing or printing it whether or not the instrument is loaded.
(xiii) Preset tare device
Device for subtracting a preset tare value from a gross weight value and indicating the result of the calculation. The weighing range for net loads is reduced accordingly.
(11) Dynamic setting
Adjustment intended to eliminate the difference between the static load value and the dynamic load value.
3. Metrological characteristics
(1) Weighing capacity
(i) Maximum capacity, Max
Maximum weighing capacity, not taking into account the addi-tive tare capacity.
(ii) Minimum capacity, Min
Value of the load below which the weighing result shall be sub-ject to an excessive relative error.
(iii) Weighing range
Range between the minimum and maximum capacities.
(iv) Maximum tare effect, T+, T–
Maximum capacity of the additive tare device or the subtrac-tive tare device.
(2) Weighing results
Note: The following definitions apply only for in-struments that weigh pre-assembled discrete loads and when the indication has been set to zero before the load has been applied to the instrument.
(i) Gross value, G or B
Indication of the weight value of a load on an instrument, with no tare or preset tare device in operation.
(ii) Net value, NET or N
Indication of the weight value of a load placed on an instru-ment after operation of a tare device.
(iii) Tare value, T
Weight value of a load, determined by a tare weighing de-vice.
(iv) Other weighing values
(a) Preset tare value, PT
Numerical value, representing a weight value, that is intro-duced into the instrument. It is a
predetermined tare value that is used for one or several weigh-ings.
Note 1: “Introduced” includes procedures such as: keying in, recalling from a data storage, or inserting via an interface.
Note 2:“Predetermined” means that a tare value is determined once and is applied to other weighings without determining the individual tare values.
(b) Calculated net value
Value of the difference between a gross or net weight value and a preset tare value.
(c) Final weight value
Weight value that is achieved when the instrument is com-pletely at rest and balanced, with no disturbances affecting the indication.
(v) Stable equilibrium
Condition of the instrument such that the printed or stored weighing values show no more than two adjacent values with one of them being the final weight value.
(vi) Critical points
Test load values at which the maximum permissible error changes.
(3) Scale divisions
(i) Actual scale interval, d
Value expressed in units of mass of:
(a) the difference between the values corresponding to two consecutive scale marks, for analog indication; or
(b) the difference between two consecutive indicated values, for digital indication.
(ii) Verification scale interval, e
Value, expressed in units of mass, used for the classification and verification of an instrument.
(iii) Number of verification scale intervals (single-interval in-strument)
Quotient of the maximum capacity and the verification scale interval:
n = Max / e
(iv) Multi-interval instrument
Instrument having one weighing range which is divided into partial weighing ranges each with different scale intervals, with the weighing range deter-mined automatically according to the load applied, both on increasing and decreasing loads.
(v) Multiple range instrument
Instrument having two or more weighing ranges with different maximum capacities and different scale intervals for the same load receptor, each range ex-tending from zero to its maximum capacity.
(4) Operational characteristics
(i) Rate of operation
Number of loads weighed automatically per unit of time.
(ii) Warm-up time
Time between the moment at which power is applied to the instrument and the moment at which the instrument is capable of complying with the re-quirements.
(iii) Non-automatic (static) operation Static weighing mode for test purposes.
(iv) Automatic operation
The instrument weighs without the intervention of the operator and follows a pre-determined program of automatic processes characteristic of the instru-ment. The instrument shall either weigh statically or dynamically in automatic operation.
(v) Instrument that weighs statically
Instrument that operates with a stable equilibrium based measuring system during the mass determining process, when the load transport system has stopped or, in the case of vehicle mounted or incorporated catchweighers, when the load re-ceptor is stationary.
(vi) Instrument that weighs dynamically
Instrument that operates with a non-stable equilibrium based measuring system during the mass determining process while the load transport system is in motion (e.g. where the load transport system is moving; checkweighers fitted with a load re-ceptor on which the load slides; or vehicle mounted or incorporated catchweigher where the load receptor is in motion).
(5) Sensitivity
For a given value of the measured mass, the quotient of the change of the observed variable,
l, and the corresponding change of the measured mass, M:
k = Δl / ΔM
(6) Repeatability
Ability of an instrument to provide results that agree one with the other when the same load is deposited several times and in a practically identical way on the load receptor under reasonably constant test conditions.
(7) Durability
Ability of an instrument to maintain its performance character-istics over a period of use.
4. Indications and errors
(1) Methods of indication
(i) Analog indication
Indication enabling the evaluation of the equilibrium position to a fraction of the scale interval.
(ii) Digital indication
Indication in which the scale marks are composed of a se-quence of aligned figures that do not permit interpolation to fractions of the scale inter-val.
(2) Reading
(i) Reading by simple juxtaposition
Reading of the weighing result by simple juxtaposition of con-secutive figures giving the weighing result, without the need for calculation.
(ii) Overall inaccuracy of reading
On an instrument with analog indication, this is equal to the standard deviation of the same indication, the reading of which is carried out under normal conditions of use by several observers. It is customary to make at least ten readings of the re-sult.
(3) Errors
(i) Error (of indication)
Indication of an instrument minus the (conventional) true value of the mass.
(ii) Rounding error of digital indication
Difference between the indication and the result the instru-ment would give with analog indication.
(iii) Intrinsic error
Error of an instrument, determined under reference condi-tions.
(iv) Initial intrinsic error
Intrinsic error of an instrument, as determined prior to the per-formance and span stability tests.
(v) Mean (systematic) error, x
Mean value of the error (of indication) for a number of consecu-tive automatic weighings of a load, or similar loads, passed over the load receptor, expressed mathematically as:
n
x = Σxi
i=1
where: n
x = error of a load indication,
x = mean of the errors, and
n = number of weighings.
(vi) Standard deviation of the error, s
Standard deviation of the error (of indication) for a number of consecutive automatic weighings of a load, or similar loads, passed over the load receptor, expressed mathematically as:
(vii) Maximum permissible error, MPE
Extreme value of an error permitted by specifications, regula-tions, etc. for a given instrument.
(viii) Fault
Difference between the error of indication of an instrument and the intrinsic error.
Note: Principally, a fault is the result of an unde-sired change of data contained in or flowing through an electronic instrument.
(ix) Significant fault
Fault greater than the verification scale interval, e.
A significant fault does not include:
(a) faults arising from simultaneous and mutually independent causes in the instrument or in its checking facility;
(b) faults that imply it is impossible to perform a measure-ment;
(c) faults that are so serious they will inevitably be noticed by all those interested in the measurement; or
(d) transitory faults that are momentary variations in the indi-cations that shallnot be interpreted, memorized or transmitted as a measurement result.
(x) Span stability
Capability of an instrument to maintain the difference between the indication at maximum capacity and the indication at zero within specified limits over a period of use.
5. Influences and reference conditions
(1) Influence quantity
Quantity that is not the measurand but that affects the result of the measurement.
(i) Influence factor
Influence quantity having a value within the specified rated op-erating conditions of the instrument.
(ii) Disturbance
Influence quantity having a value within the limits specified in this specification but outside the rated operating conditions of the instrument.
(2) Rated operating conditions
Conditions of use, giving the ranges of the measurand and of the influence quantities for which the metrological characteristics are intended to lie within the maximum permissible errors specified in this specification.
(3) Reference conditions
Set of specified values of influence factors fixed to ensure valid inter-comparison of the results of measurements.
6. Tests
(1) Operational test
Test carried out on a complete instrument using a test load or loads of the type that it is intended to weigh, and using the load conveyor or load transport sys-tem to move it on to and off the load receptor.
(2) Simulation test
Test carried out on a complete instrument or part of an instru-ment in which any part of the weighing operation is simulated.
(3) Performance test
Test to verify that the equipment under test (EUT) is able to ac-complish its intended functions.
(4) Span stability test
Test to verify that the EUT is capable of maintaining its perfor-mance characteristics over a period of use.
- Abbreviations and symbols
Part II
Metrological and Technical requirements
1. General
(1) Scope
This Part specifies the metrological and technical requirements and test procedures for auto-matic catch weighing instruments (catchweighers), herein after called “instruments”.
It is intended to provide standardized requirements and testing procedures to evaluate the metrological and technical characteristics in a uniform and traceable way.
(2) Application
This specification applies to instruments that automatically weigh discrete loads or single loads of loose material.
2. Metrological Requirements
(1) Accuracy classes
Instruments are divided according to their use into two primary categories designated by:
X or Y
Category X applies only to checkweighers used to check pre-packed products
Category Y applies to all other automatic catchweighing instruments such as weigh-price la-belers, postal and shipping scales, and instruments that weigh single loads of loose material.
Note: An instrument shall be classified as both category X and category Y, e.g. where an instrument is configured with two separate modes of operation which enable it to operate either as a checkweigher or as a weigh-price labeler.
(i) Category X
The primary category is further divided into four accuracy classes:
XI, XII, XIII and XIIII
The accuracy classes are supplemented by a factor (x) which is specified by the manufacturer. The value of (x) shall be1×10k, 2×10k, or 5×10k, k being a positive or negative whole number or zero.
(ii) Category Y
The primary category is further divided into four accuracy classes:
Y(I), Y(II), Y(a), and Y(b)
(2) Classification of instruments
(i) Verification scale interval
The verification scale interval and number of verification scale intervals ,in relation to the ac-curacy class, are given in Table 1.
Table1
| Accuracy class | Verification scaleinterval,e |
Number of verification scale intervals n= Max /e |
||
| Minimum | Maximum | |||
| (1) | (2) | (3) | (4) | (5) |
| XI | Y(I) | 0.001g e* | 50000 | – |
| XII | Y(II) | 0.001g e 0.05g | 100 | 100000 |
| 0.1ge | 5000 | 100000 | ||
| XIII | Y(a) | 0.1ge 2 g | 100 | 10000 |
| 5g e | 500 | 10000 | ||
| XIIII | Y(b) | 5g e | 100 | 1000 |
*It is normally not feasible to test and verify an instrument where e<1 mg due to the uncertainty of the test loads.
On multiple range instruments the verification scale intervals are e1,e2,…,er with e1<e2<…<er. Min, n and Max are in-dexed accordingly.
On multiple range instruments, each range is treated basically as an instrument with one range.
(ii) Minimum capacity, Min
Min shall be specified by the manufacturer.
For category Y instruments, Min shall not be less than:
ClassY(I): 100e
ClassY(II): 20e for 0.001g e 0.05g, and
50e for 0.1g e
ClassY(a): 20e
ClassY(b): 10e
Scales used for grading, postal scales
and garbage weighers: 5 e
(3) Additional requirements for a multi-interval instrument
(i) Partial weighing range
Each partial weighing range (index, i=1,2…) is defined by:
(a) Its verification scale interval , ei+1>ei;
(b) Its maximum capacity Maxi;
(c) its minimum capacity Mini= Maxi– 1 (for i = 1, the minimum capacity is Min1 = Min).The number of verification scale intervals ni for each partial range is:
ni = Maxi / ei
(ii) Accuracy class
ei and ni in each partial weighing range shall comply with the requirements given in Table 1 according to the accuracy class of the instru-ment. Min1 shall comply with the requirements given in clause (ii) of sub-paragraph(2) of par-agraph 2 of Part II according to the accuracy class of the instrument.
(iii) Maximum capacity of partial weighing ranges
With the exception of the last partial weighing range, the requirements in Table 2 shall be complied with, according to the accuracy class of the instrument.
Table2
| (1) | (2) | (3) | (4) | (5) |
| Category
X |
XI | XII | XIII | XIIII |
| Category
Y |
Y(I) | Y(II) | Y(a) | Y(b) |
| Maxi/ei+1 | 50 000 | 5 000 | 500 | 50 |
(iv) Instrument with a tare device
Requirements concerning the ranges of a multi-interval instrument apply to the net load, for every possible value of the tare.
(v) Example for a multi-interval instrument
Maximum capacity: Max= 2/ 5 /15 kg
Class: Y(a)
Verification scale interval: e =1 / 2 / 10g
This instrument has one Max and one weighing range from Min = 20 g to Max =
15 kg. The partial weighing ranges are:
Min1 = 20 g, Max1 = 2 kg, e1 = 1 g, n1 = 2000
Min2 = 2 kg, Max2 = 5 kg, e2 = 2 g, n2 = 2500
Min3 = 5 kg, Max3 = Max = 15 kg, e3 = 10 g, n3 = 1 500
For automatic operation the maximum permissible errors on initial verification (MPE) are:
| For m = | 400 g | = | 400 e1 | MPE = | 1.0 g |
| For m = | 1600 g | = | 1600 e1 | MPE = | 1.5 g |
| For m = | 2100 g | = | 1050 e2 | MPE = | 3.0 g |
| For m = | 4250 g | = | 2125 e2 | MPE = | 4.0 g |
| For m = | 5100 g | = | 510 e3 | MPE = g | 15.0 |
| For m = 15000 g | = | 1500 e3 | MPE = g | 15.0 | |
Whenever the variation of the indication due to certain influence factors is limited to a frac-tion or multiple of e, this means, in a multi-interval instrument, that e is to be taken according to the load applied; in particular, at or near zero load e = e1.
(4) Auxiliary indicating device
For instruments fitted with an auxiliary indicating device such as an indicating device with a differentiated scale division (Figure1), the device is permitted only to the right of the decimal sign.
Figure1–Examples of indicating devices each with a differentiated scale division
For category Y(a) and Y(b) instruments, the use of auxiliary indicating devices shall be limited to testing applications only.
A multi-interval instrument shall not be fitted with an auxiliary indicating device.
Note: Extended indicating devices are not regarded as auxiliary indicating devic-es.
(5) Maximum permissible errors
(i) Automatic operation
(a) Category X instruments
For a number of consecutive weighings of a net load, greater than or equal to the minimum capacity, Min, and less than or equal to the maximum capacity, Max, the maximum permissi-ble mean (systematic) error shall be as specified in Table 3.
Table 3
| Net load, m, expressed in verification scale inter-vals, e | Maximum permissible mean error for category X instruments |
||||||||
| XI | XII | XIII | XIIII | Initial verificatio n | In-
service inspectio n |
||||
| (1) | (2) | (3) | (4) | (5) | (6) | ||||
| 0<m | 50000 | 0<m | 5 000 | 0 <m | 500 | 0 <m | 50 | ±0.5e | ±1e |
| 50000 <m | 200 000 | 5000 <m | 20
000 |
500<m | 2000 | 50<m | 200 | ±1e | ±2e |
| 200000 <m | 20000 <m | 100 000 | 2000 <m | 10000 | 200<m | 1 000 | ±1.5e | ±3e | |
The maximum permissible standard deviation of the error (random error) shall be as specified in Table 4, multiplied by the class designation factor (x).
Table 4
| Value of the mass of the net load, m (g) |
Maximum permissible standard deviation(as a percentage of m or in grams) For class designation factor,(x) =1 |
|
| Initial verification | In-service inspection |
|
| (1) | (2) | (3) |
| m50 | 0.48% | 0.6% |
| 50<m 100 | 0.24g | 0.3g |
| 100<m 200 | 0.24% | 0.3% |
| 200<m 300 | 0.48g | 0.6g |
| 300<m 500 | 0.16% | 0.2% |
| 500<m 1000 | 0.8g | 1.0g |
| 1000<m 10 000 | 0.08% | 0.1% |
| 10000<m 15 000 | 8g | 10g |
| 15000<m | 0.053% | 0.067% |
(I) For classes XI and XII, (x) shall be less than 1;
(II) For class XIII, (x) shall be not greater than 1;
(III) For class XIIII, (x) shall be greater than 1.
(b) Category Y instruments
The maximum permissible error for any load greater than or equal to the Min and less than or equal to the Max in automatic operation shall be as specified in Table5
Table 5
| Load, m, expressed in verification scale intervals, e | Maximum permissible error for category Y instruments* |
||||||||
| Y(I) | Y(II) | Y(a) | Y(b) | Initial verificatio n | In- service inspectio n |
||||
| (5) | (6) | ||||||||
| 0 < m | 50000 | 0<m | 5000 | 0< m | 500 | 0< m | 50 | ±1e | ±1.5e |
| 50000 < m 000 | 200 | 5000 <m | 20000 | 500< m | 2000 | 50< m | 200 | ±1.5e | ±2.5e |
| 200000 < m | 20000 <m | 100 000 | 2000 < m | 10000 | 200< m | 1000 | ±2e | ±3.5e | |
* This MPE is applicable for instruments with a device for displaying the digital indication with d ≤0.2 e. For instruments without a device for displaying the indica-tion with d ≤0.2 e the procedure in sub clause (b) of clause (ii) of subparagraph (9) of paragraph 3 of Annexure A shall be applied.
If the net weight value is calculated by subtraction of two individual weighings, the MPEs only apply:
(a) to these individual weighings if they are printed or recorded separately; or
(b) to the net weight value if only the net weight value is print-ed.
(ii) Non-automatic(static) operation
Note: This paragraph concerns the mode defined in clause (iii) of sub-paragraph(4) of paragraph 3 of Part I and is therefore not applicable for the automatic(static) weighing mode.
For category X and category Y instruments, the maximum permissible error for any load great-er than or equal to the Min and less than or equal to the Max in nonautomatic (static) opera-tion shall be as specified in Table 6.
Table6
| Load, m, expressed in verification scale intervals, e |
Maximum permissible error for category X and category Y instruments |
||||
| XI and Y(I) | XII and Y(II) | XIII and Y(a) | XIIII and Y(b) | Initial verificatio n | In-
service inspectio n |
| (1) | (2) | (3) | (4) | (5) | (6) |
| 0<m 50 000 | 0<m 5000 | 0<m 500 | 0 <m 50 | ±0.5e | ±1e |
| 50000 <m 200 000 | 5000 <m 20 000 | 500<m 2000 | 50<m 200 | ±1e | ±2e |
| 200000 <m | 20000 <m 100 000 | 2000 <m 10000 | 200<m 1 000 | ±1.5e | ±3e |
(6) Maximum permissible errors for influence factor tests
(i) Category X instruments
For automatic operation:
(a) the maximum permissible mean error shall be as specified in Table 3 for initial verification; and
(b) the maximum permissible standard deviation of the error shall be as specified in Table 4 for initial verification multiplied by the class designation factor (x).
For non-automatic (static) operation the maximum permissible errors shall be as specified in Table 6 for initial verification.
(ii) Category Y instruments
For automatic operation the maximum permissible errors for each load shall be as specified in Table 5 for initial verification.
For non-automatic (static) operation the maximum permissible errors shall be as specified in Table 6 for initial verification.
(7) Units of measurement
The units of mass to be used on an instrument are:
(i) metric carat(ct);
(i) milligram(mg);
(iii) gram(g);
(iv) kilogram(kg);
(v) tonne (t).
Note: The metric carat (1 carat = 0.2 g) shall be used as the unit of measurement for special applications such as trade in precious stones.
(8) Permissible differences between results
(i) Effect of eccentric loading
If it is possible to pass loads eccentrically, the maximum per-missible errors given in the appropriate part or parts of sub-paragraph (5) of paragraph 2 of this part shall not be exceeded at any eccentric setting.
(ii) Agreement between indicating and printing devices
For the same load, the difference between the weighing results [Para 3(2) of part I] provided by any two devices having the same scale interval shall be as fol-lows:
(a) zero for digital displaying and printing devices;
(b) not greater than the absolute value of the maximum per-missible error for automatic weighing for analog devices.
(9) Influence factors
Refer to Annexure A for test conditions.
(i) Temperature
(a) Temperature limits
If no particular working temperature is stated in the descriptive markings of an instrument, this instrument shall maintain its metrological properties within the following temperature limits:
–10°C to +40°C
(b) Special temperature limits
An instrument for which particular limits of working tempera-ture are stated in the descriptive markings shall comply with the metrological requirements within those limits. The limits shall be chosen according to the application of the instru-ment.
The ranges within those limits shall be at least equal to:
(I) 5 °C for instruments of classes XI and Y(I);
(II) 15 °C for instruments of classes XII and Y(II);
(III) 30 °C for instruments of all other classes.
(c) Temperature effect on no-load indication
The indication at zero or near zero shall not vary by more than one verification scale interval for a difference in ambient temperature of 1 °C for instruments of classes XI and Y(I), and 5 °C for other classes.
(ii) Voltage supply
An electronic instrument shall comply with the appropriate metrological and technical requirements, if the voltage supply varies from the nominal volt-age, Unom(if only one voltage is marked on the instrument), or from the lower and upper limits of the voltage range, Umin and Umax, marked on the instrument at:
(a) AC mains voltage:
(I) lower limit is 85 % of Umin,
(II) upper limit is 110 % of Umax;
(b) DC mains voltage, including rechargeable battery if the bat-tery shall be fully (re)charged during the operation of the instrument:
(I) lower limit is the minimum operating voltage,
(II) upper limit is 120 % of Umax (Umax is the voltage of a new or fully charged rechargeable battery of the type specified by the manu-facturer);
(c) DC battery supply, including non-rechargeable battery sup-ply, and also including rechargeable battery supply if the batteries shallnot be (re)charged dur-ing operation of the instrument:
(I) lower limit is the minimum operating voltage,
(II) upper limit is Unom;
(d) 12 V or 24 V road vehicle battery supply:
(I) lower limit is 9 V (for a 12 V battery) or 16 V (for a 24 V bat-tery),
(II) upper limit is 16 V (for a 12 V battery) or 32 V (for a 24 V bat-tery).
Note: The minimum operating voltage is defined as the lowest possible operating voltage before the instrument is automatically switched off.
Battery-operated and DC mains powered instruments shall either continue to function cor-rectly or not indicate any weight values if the voltage is below the manufacturer’s specified value, the latter being larger or equal to the minimum operating voltage.
(iii) Tilting
Instruments which are not intended for installation in a fixed position and which do not have a leveling device and a level indicator shall comply with the appropriate metrological and tech-nical requirements when tilted (longitudinally and transversely) by 5 %, or when tilted to a pre-determined value selected by the manufacturer if the instrument is provided with a tilt limit-ing device which prevents the instrument from operating when tilted above this value.
Where a leveling device and a level indicator are present they shall enable the instrument to be set to atilt of 1 % or to the limiting value of tilting as defined by an obvious marking on the level indicator,(e.g. a ring, or a legible notice provided on the instrument in a clearly visible place that points the user to the level indicator). The level indicator shall be fixed firmly on the instrument in a place clearly visible to the user and representative for the tilt sensitive part.
Instruments mounted on or incorporated in vehicles shall comply with the appropriate metro-logical and technical requirements when tilted (longitudinally and transversely) by 10 %, or when tilted to a lower predetermined value selected by the manufacturer, e.g. 3 %, if the in-strument is provided with an automatic tilt limiting device which prevents the instrument from operating when tilted above this value.
(10) Span stability
When the instrument is subjected to the span stability test specified in paragraph 7 of Annex-ure A, the absolute value of the difference between the errors obtained for any two measure-ments shall not exceed the maximum span error.
The maximum span error is equal to half the maximum permissible error for influence factor tests for a near maximum capacity load.
(11) Indication or print out for test purposes (automatic operation)
For category X instruments, practical means shall be provided in accordance with clause (viii) of sub-paragraph (1) of paragraph 6 of this part for determining the mean error and the stand-ard deviation of the error to demonstrate compliance with Tables 3 and 4, e.g. indications and/or print-outs of the mass (or the difference between the mass and a nominal set-point).
Note: In normal operation, the sorting device of category X instruments shall work with the same or smaller scale interval, d, which is used for determining the mean error and standard deviation of the error during type/model approval and initial verification testing.
For category Y instruments, practical means for determining the individual errors of weighings shall be provided in accordance with sub clause(b) of clause(vii) of sub-paragraph(1) of para-graph 6 of this part to demonstrate compliance with Table 5.
3. Technical Requirements
(1) Suitability for use
An instrument shall be designed to suit the method of operation and the loads for which it is intended. It shall be of adequately robust construction to ensure that it maintains its metro-logical characteristics.
(2) Security of operation
(i) Fraudulent use
An instrument shall have no characteristics likely to facilitate its fraudulent use.
(ii) Accidental break down and maladjustment
An instrument shall be so constructed that an accidental breakdown or maladjustment of control elements likely to disturb its correct functioning shallnot take place without its effect being evident.
(iii) Dynamic setting
An instrument shall be fitted with a dynamic setting facility to compensate for the dynamic effects of the load in motion. This facility shall operate over a weighing range relative to a set-ting weight value provided that when the facility is used for that weighing range and in accord-ance with the manufacturer’s instructions, the maximum permissible errors are not exceeded.
Once dynamic setting has taken place to give a weighing range over which the permissible errors are not exceeded, the instrument shall automatically take appropriate action for loads falling outside that range; for these loads, printout of the weight shall also be inhibited.
Instruments with dynamic setting available to the user not secured in accordance with of clause(vi) of sub-paragraph(2) of paragraph 3 of this part shall have a facility to automatically and non-erasably record any adjustment of the dynamic setting, e.g. an event logger. The in-strument shall be capable of presenting the recorded data.
(iv) Controls
Controls shall be so designed that they shallnot normally come to rest in positions other than those intended by design, unless during the manoeuvre all indication is made impossible. Keys shall be marked unambiguously.
(v) Tilt limiting device
An instrument mounted on a vehicle shall be provided with a tilt limiting device which
prevents the instrument from operating if the vehicle is tilted (longitudinally and transversely) above a predetermined value set by the manufacturer.
(vi) Securing
Means shall be provided for securing components, interfaces, device-specific parameters and preset controls to which access or adjustment is prohibited. National regulations shall specify the securing that is required. On classes XI and Y(I) instruments, devices to adjust sensitivity (or span) shall remain unsecured.
The introduction into the instrument of data that shall influence the instrument’s metrological properties or measurement results shall be prevented, e.g. by a protective interface.
Components and preset controls shall be secured by passwords or similar software means provided that any access to the secured controls or functions becomes automatically evident, e.g. by automatically updating a device-specific parameter the value of which at the time of the last verified setup had been durably marked on the instrument in accordance with the re-quirements of clause (iv) of sub-paragraph (11) of paragraph 3 of this part.
An instrument shall be fitted with a span adjustment device. External influence upon this de-vice shall be practically impossible after securing.
(vii) Sorting device
The sorting device of a category X instrument shall automatically divide loads into separate sub- groups depending on their mass.
(3) Indication of weighing results
(i) Quality of reading
Reading of the primary indications shall be reliable, easy and unambiguous under conditions of normal use:
(a) the overall inaccuracy of reading of an analog indicating de-vice shall not exceed 0.2 e;
(b) the figures, units and designations forming the primary indi-cations shall be of a size, shape and clarity for reading to be easy.
The scales, numbering and printing shall permit the figures which form the results to be read by simple juxtaposition.
(ii) Form of the indication
Weighing results shall contain the names or symbols of the units of mass in which they are expressed. For any one indication of weight value, only one unit of mass shall be used.
The scale interval for weighing results shall be in the form 1 10k, 2 10k or 5 10k units in which the result is ex-pressed, k being a positive or negative whole number or zero.
All indicating, printing and tare weighing devices of an instrument shall, within any one weigh-ing range, have the same scale interval for any given load.
A digital indication shall display at least one figure beginning at the extreme right.
A decimal fraction shall be separated from its integer by a decimal sign (comma or dot), with the indication showing at least one figure to the left of the sign and all figures to the right.
Zero shall be indicated by one zero to the extreme right, without a decimal sign.
The unit of mass shall be chosen so that the weight values have not more than one non-significant zero to the right. For values with a decimal sign, the non-significant zero is allowed only in the third position after the decimal sign. The units of mass shall be written in small let-ters (lower case) as indicated in sub-paragraph (7) of paragraph 2 of this part.
The unit of mass shall be chosen so that the weight values have not more than one non-significant zero to the right. For values with a decimal sign, the non-significant zero is allowed only in the third position after the decimal sign. The units of mass shall be written in small let-ters (lower case) as indicated in sub-paragraph (7) of paragraph 2 of this part.
(iii) Limits of indication
Category Y: There shall be no indication, printing, storing or transmission of weight values above Max+ 9 e.
Category X: There shall be no indication, printing, storing or transmission of weight values above Max + 9 e or Max + three times the maximum permissible standard devia-tion value as specified in Table 4, whichever is the greater.
(iv) Indication or print out for normal operation
For normal operation the scale interval of indications or printouts of individual article weights shall be the verification scale interval, e.
The scale interval of indications or printouts of the mean (systematic) error and the standard deviation of the error (or indication), for a number of consecutive automatic weighings of a load, shall be to a higher resolution than the verification scale interval, e.
(4) Digital indicating, printing and memory storage devices
The following requirements apply in addition to those in clause (i) sub-paragraph
(3) of paragraph 3 – clause(iv) sub-paragraph (3) of paragraph 3 of this Part.
(i) Stable equilibrium
For instruments that weigh statically, equilibrium is deemed to be stable when:
(a) in the case of printing and/or data storage, the printed or stored weighing values show no more than two adjacent values, one of them being the final weight value ;and
(b) in the case of zero or tare operations, a correct operation according to Para clause(iii) sub-paragraph (4) of paragraph 3 of this part (printing), clause(v) subparagraph (5) of paragraph 3 of this part (control of zero-setting), clause(iv) sub-paragraph (5) of paragraph 3 of this part (stability of automatic zero-setting), clause(v) sub-paragraph (5) of paragraph 3 of this part (zero-tracking) and clause(vii) sub-paragraph (6) of paragraph 3 of this part (tare-weighing) of the device within relevant accuracy requirements is achieved. Both conditions shall also be met under continuous or temporary disturbance of the equilibri-um. For instruments that weigh dynamically, no separate criteria for stable equilibrium are given.
(ii) Extended indicating device
An extended indicating device shall not be used on an instrument with an auxiliary indicating device.
When an instrument is fitted with an extended indicating device, displaying the indication with a scale interval smaller than e shall be possible only:
(a) whilst a particular key is pressed; or
(b) for a period not exceeding 5 seconds after a manual com-mand. In any case printing shall not be possible.
(iii) Printing device
Printing shall be clear and permanent for the intended use. Printed figures shall be at least 2 mm high.
If printing takes place, the name or the symbol of the unit of measurement shall be either to the right of the value or above a column of values.
Printing shall be inhibited if the stability criteria clause (i) sub-paragraph (4) of paragraph 3 of this part are not fulfilled.
(iv) Data storage device
The primary indications shall be stored in a memory of the instrument or on external storage for subsequent use (e.g. indication, printing, data transfer, totalizing, etc.). In this case, the stored data shall be adequately protected against intentional and unintentional changes dur-ing the data transmission and/or storage process and shall contain all relevant information necessary to reconstruct an earlier measurement.
The storage of primary indications shall be inhibited if the stability criteria are not fulfilled.
(v) Software
The software used in the instrument must be present in such a form that alteration of the software is not possible without breaking a seal, or any change in the software shall be sig-naled automatically by means of an identification code.
The software shall be adequately protected against accidental or intentional changes. Evi-dence of an intervention such as changing, uploading or circumventing the legally relevant software shall be available until the next verification or inspection.
The software shall be assigned a fixed software identification. This fixed software identifica-tion shall be adapted in the case of every software change that shall affect the metrological functions of the instrument.
Software documentation provided with the instrument shall include the following:
(a) A description of the system hardware, e.g. topology block diagram, type of computer(s), source code for software functions, etc. and legally relevant software environment;
(b) A description of the fixed software version number and/or software identification that is assigned to the metrologically relevant functions;
(c) A description of the relevant menus and dialogues;
(d) The securing measures foreseen (e.g. checksum, signature, audit trail);
(e) A description of the data storage device(s);
(f) The operating manual.
(5) Zero-setting and zero-tracking devices
An instrument shall have one or more zero-setting devices and shall not have more than one zero- tracking device. These devices shall be non-automatic, semiautomatic or automatic.
(i) Maximum effect
The effect of any zero-setting device shall not alter the maximum weighing capacity of the in-strument.
The overall effect of zero-setting and zero-tracking devices shall not be more than 4 %, and of the initial zero-setting device not more than 20 %, of the maximum capacity.
A wider range is possible for the initial zero-setting device if tests show that the instrument complies with the maximum permissible errors in sub-paragraph (5) of paragraph 2 and subparagraph (6) of paragraph 2 of this part, the permissible differences in errors in subparagraph (8) of paragraph 2 of this part, and the influence factors in sub-paragraph (9) of paragraph 2 of this part, for any load compensated by this device within the specified range.
(ii) Accuracy
After zero-setting the effect of zero deviation on the result of the weighing shall be not more than 0.25 e.
(iii) Control of the zero-setting devices
An instrument, whether or not equipped with an initial zero-setting device, shall have a com-bined semi-automatic zero-setting and semi-automatic tare-balancing device operated by the same key.
If an instrument has a zero-setting device and a tare-weighing device, the control of the zero-setting device shall be separate from that of the tare-weighing device.
A semi-automatic zero-setting device shall function only:
(a) when the instrument is in stable equilibrium ;
(b) if it cancels any previous tare operation.
A non-automatic or semi-automatic zero-setting device shall not be operable during automat-ic operation.
(iv) Stability of automatic zero-setting device
An automatic zero-setting device shall operate at the start of automatic operation, as part of every automatic weighing cycle, or after a programmable time interval. A description of the operation of the automatic zero-setting device (e.g. the maximum programmable time inter-val) shall be included in the type / model approval certificate.
The automatic zero-setting device shall operate:
(a) only when the stability criteria are fulfilled; and
(b) sufficiently often to ensure that zero is maintained within 0.5 e.
Where the automatic zero-setting device operates as part of every automatic weighing cycle, it shall not be possible to disable this device or to set it to operate at time intervals.
Where the automatic zero-setting device operates after a programmable time interval, the manufacturer shall specify the maximum time interval. The maximum programmable time interval shall not be greater than the value necessary to ensure that the zero error is not great-er than 0.5 e.
The maximum programmable time interval for automatic zero-setting required above shall start again after tare weighing or zero tracking has taken place.
The actual maximum programmable time interval for automatic zero-setting shall be speci-fied taking into account the actual operating conditions of the instrument. The automatic zero-setting device shall either automatically set to zero after the allocated time or shall stop the instrument so that a zero- setting operation shall occur or be capable of generating infor-mation to draw attention to overdue zero- setting.
(v) Zero-tracking device
A zero-tracking device shall operate only when:
(a) the indication is at zero, or at a negative net value equiva-lent to gross zero;
(b) the stability criteria are fulfilled; and
(c) the corrections are not more than 0.5 e/second.
When zero is indicated after a tare operation, the zero-tracking device shall operate within a range of 4 % of Max around the actual zero.
Note: Zero-tracking is functionally similar to automatic zero-setting. The differ-ences are important in applying the requirements of 3.5. Refer to sub clause(c) of clause (viii) of sub-paragraph (10) of paragraph 2 and clause (ix) of subparagraph (10) of paragraph 2 of Part I For many types of catchweigher, which have automatic zero-setting, zero-tracking will not be appropriate. The maximum rate of correction applicable to zero-tracking does not apply to zero-setting.
(I) Automatic zero-setting is activated by an event, such as part of every automatic weighing cycle or after a programmed interval;
(II) Zero-tracking shall operate continuously and must therefore be subject to a maximum rate of correction (0.5 e/second) to prevent interaction with the normal weighing process.
(6) Tare device
(i) Scale interval
The scale interval of the tare device shall be equal to the scale interval of the instrument for any given load.
(ii) Accuracy
A tare device shall permit setting the indication to zero with a deviation of not more than 0.25 e. On a multi-interval instrument, e shall be replaced by e1.
(iii) Operating range
The tare device shall be such that it shallnot be used at or be-low its zero effect or above its maximum indicated effect.
(iv) Visibility of operation
Operation of the tare device shall be visibly indicated on the instrument. In the case of instruments with digital indication this shall be done by marking the indicated net value with the sign “NET” or “N”, and if applicable, the indicated tare value with the sign “T”.
Note 1: “NET” shall also be displayed as “Net” or “net”.
Note 2: If an instrument is equipped with a device that allows the gross value to be displayed temporarily while a tare device is in operation, the “NET” symbol shall disappear while the gross value is displayed.
This is not required for an instrument with a combined semi-automatic zero-setting device and a semi-automatic tare-balancing device operated by the same key.
It is permitted to replace the symbols “NET” and “T” by com-plete words in an official language of the country where the instrument is used.
(v) Subtractive tare device
When the use of a subtractive tare device does not allow the value of the residual weighing range to be known, a device shall prevent the use of the instru-ment above its maximum capacity or indicate that this capacity has been reached.
(vi) Multiple range instrument
On a multiple range instrument the tare operation shall be effective also in the greater weighing ranges, if switching to a greater weighing range is possi-ble while the instrument is loaded.
(vii) Operation of tare devices
Semi-automatic or automatic tare devices shall operate only when the stability criteria are fulfilled.
A non-automatic or semi-automatic tare device shall not be operable during automatic operation.
(viii) Combined zero-setting and tare-balancing devices
If the semi-automatic zero-setting device and the semi-automatic tare-balancing device are operated by the same key, clause(ii) sub-paragraph (5) of paragraph 3 of this part (zero-setting accuracy) and if appropriate clause(ii) of sub-paragraph (6) of paragraph 3 of this part (tare setting accuracy), apply at any load.
(ix) Consecutive tare operations
Repeated operation of a tare device is permitted. If more than one tare device is operative at the same time, tare weight values shall be clearly designated when indicated or printed.
(x) Printing of weighing results
Gross weight values shall be printed without any designation. For a designation by a symbol, only “G” or “B” are permitted.
If only net values are printed without corresponding gross or tare values, they shall be printed without any designation. A symbol for designation shall be “N”. These conditions apply also where semi-automatic zero-setting and semi-automatic tare balancing are initiated by the same key.
Gross, net, or tare values determined by a multiple range in-strument or a multi-interval instrument need not be marked by a special designation referring to the (partial) weighing range.
If net values are printed together with the corresponding gross and/or tare values, the net and tare values shall at least be identified by the corresponding symbols “N” and “T”.
However, it is permitted to replace the symbols G, B, N and T by complete words in an official language of the country in which the instrument is used.
If net values and tare values determined by different tare de-vices are printed separately, they shall be suitably identified.
(7) Preset tare device
(i) Scale interval
For Category X instruments the preset tare scale interval, dT, shall be equal to or smaller than the verification scale interval, e, of the instrument.
For Category Y instruments the preset tare scale interval, dT, shall be equal to or automatically rounded to the scale interval, d, of the instrument.
On a multiple range instrument a preset tare value shall only be transferred from one weighing range to another one with a larger verification scale interval but shall then be rounded to the latter. For a multi-interval instrument, the preset tare value shall be entered with the smallest verification scale interval, e1, of the instru-ment, and the maximum preset tare value shall not be greater than Max1. The indicated or printed calculated net shall be rounded to the scale interval of the instrument for the same net weight value.
(ii) Modes of operation
A preset tare device shall be operated together with one or more tare devices provided that:
(a) clause(ix) of sub-paragraph(6) of paragraph(3) of this part (consecutive tare operations) is respected; and
(b) a preset tare operation shall not be modified or shallcelled as long as any tare device operated after the preset tare operation is still in use.
Preset tare devices shall operate automatically only if the pre-set tare value is clearly identified with the load to be measured (e.g. by bar code identification on the container).
(iii) Indication of operation
For the indicating device clause (iv) of sub-paragraph (6) of paragraph (3) of this part (visibility of operation) applies. It shall be possible to indicate the preset tare value at least temporarily.
Clause(x) of sub-paragraph (6) of paragraph (3) of this part ap-plies accordingly provided that:
(a) if the calculated net value is printed at least the preset tare value is printed as well;
(c) preset tare values are designated by the symbol “PT”; how-ever, it is permitted to replace the symbol “PT” by complete words in an official language of the country in which the instrument is used.
(8) Selection of weighing ranges on a multiple range instrument
The range that is actually in operation shall be clearly indicated.
(i) Manual selection
Manual selection of the weighing range is allowed:
(a) from a smaller to a greater weighing range, at any load;
(b) from a greater to a smaller weighing range, when there is no load on the load receptor, and the indication is zero or at a negative net value; the tare opera-tion shall be shallcelled, and zero shall be set to ±0.25 e1, both automatically.
Manual selection of the weighing range shall be inhibited dur-ing automatic operation.
(ii) Automatic selection
Automatic changeover is allowed:
(a) from a smaller to the following greater weighing range when the load exceeds the maximum gross weight value of the range being operative;
(b) only from a greater to the smallest weighing range when there is no load on the load receptor, and the indication is zero or at a negative net value; the tare operation shall be shallcelled and zero shall be set to ±0.25 e1, both automat-ically.
(9) Devices for selection (or switching) between various load receptors, load-transmitting de-vices and load-measuring devices
(i) Compensation of no-load effect
The selection device shall ensure compensation for the une-qual no-load effect of the various load receptors and/or load-transmitting devices in use.
(ii) Zero-setting
Zero-setting of an instrument with any multiple combination of various load- measuring devices and various load receptors shall be possible without ambigui-ty and in accordance with the provisions of sub-paragraph(5) of paragraph3 of this part.
(iii) Impossibility of weighing
Weighing shall not be possible while selection devices are be-ing used. (iv) Identification of the combinations used Combinations of load receptors and load-measuring devices used shall be readily identifiable.
(10) Weigh or weigh-price labeling instrument
A weigh or weigh-price labeling instrument shall have at least one displaying device for the weight value. It shall be used temporarily for set up purposes such as supervision of weight value setting limits, unit sale prices, preset tare values and commodity names.
It shall be possible to verify the actual value of unit sale price and preset tare during automatic operation.
(i) Price computing
The price to pay shall be calculated and rounded off to the nearest two decimal places to pay by multiple indication of weight value and unit sale price, both as indicated or printed by the instrument. The device which performs the calculation is considered a part of the instrument.
The unit price or unit sale price shall be in the form of rules made under the Act.
(ii) Totalization
An instrument shall totalize weight values and price data on one or more tickets or labels provided that the total values are identified by a special word or symbol. All totals shall be the algebraic sums of all the values printed.
(iii) Printing
When price computing transactions performed by the instru-ment are printed, the weight value, unit sale price and retail sale price to pay shall all be print-ed.
The data shall be stored in a memory of the instrument before printing. The same data shall not be printed twice on the ticket or label.
Printing below minimum capacity shall not be possible.
(11) Descriptive markings
Automatic catchweighing instrument shall bear the following markings,-
(i) Markings shown in full
(a) name or identification mark of the manufacturer
(b) name or identification mark of the importer (if applica-ble)
(c) serial number and type designation of the instrument
(d) maximum rate of operation (if applicable) in the form: . loads/min or units/min
(e) maximum speed of load transport system (if applicable) in the form:………………………………………………………………….. m/s or m/min
(f) electrical supply voltage in the form:…………………………… V
(g ) electrical supply frequency in the form:………………………. Hz
(h) pneumatic/hydraulic pressure (if applicable) in the form: kPa
(i) adjustment range referred to set point (if applicable) in the form: ±. … g or % (of set point value)
(j) temperature range (when not –10 °C to +40 °C)
(k) software identification (if applicable)
(ii) Markings shown in code
(a) Type/model approval sign
(b) indication of the accuracy class, e.g. XI (0.5) or Y(a)
(c) verification scale interval in the form:………………………………….. e =
(d) actual scale interval in the form:…………………………………………. d =
(e) maximum capacity in the form:………………………………………………………………… Max
(f) minimum capacity in the form:……………………………………………………………… Min
(g) maximum additive tare in the form: T = +
(h) maximum subtractive tare in the form: T = –
(iii) Supplementary markings
Depending upon the particular use of the instrument, supplementary markings shall be re-quired on type/model approval by the metrological authority issuing the type/model approval certificate (for example: securing code, date of manufacture).
Additional markings (for example, products) shall be required on initial verification to specify types of packs and related weighing conditions.
(iv) Presentation of descriptive markings
Descriptive markings shall be indelible and of a size, shape and clarity that permit legibility under normal conditions of use.
Descriptive markings shall either be in Hindi in Devnagri script or in English.
They shall be grouped together in a clearly visible place on the instrument, either on a descrip-tive plate or sticker fixed permanently to the instrument, or on a non-removable part of the in-strument itself. In the case of a plate or sticker which is not destroyed when removed, a means of securing shall be provided, e.g. a non-removable control mark that shall be applied.
It shall be possible to seal the plate bearing the markings, unless it shall not be removed with-out being destroyed.
Alternatively, the descriptive markings shall be simultaneously shown on a display which is controlled by software either permanently or on manual command provided that:
(a) the markings: Max…, Min…, e, d if d e, and X(x) and/or Y(y) shall be shown at least in one place and permanently ei-ther on the display or near to the display in a clearly visible position, and are permanently and simultaneously shown (or alternating one after each other) on the display of the weighing re-sult as long as the instrument is switched on;
(b) the other markings shall be shown on manual com-mand;
(c) the markings are considered as device-specific parameters and shall comply with the requirements for securing in clause(vi) of sub-paragraph(2) of para-graph 3 of this part.
When a software controlled display is used, the plate of the instrument shall bear at least the following markings:
(d) max, min and d shall be shown near the display if not already located there;
(e) type/model approval sign ;
(f) name or identification mark of the manufacturer/ type/ seri-al number;
(g) electrical supply voltage;
(h) electrical supply frequency;
(i) pneumatic/ hydraulic pressure.
(12) Verification marks
(i) Position
Instruments shall have a place for the application of verification marks. This place shall:
(a) be such that the part on which it is located shall not be re-moved from the instrument without damaging the marks;
(b) allow easy application of the mark without changing the metrological qualities of the instrument;
(c) normally be visible without the instrument having to be moved when it is in service.
(ii) Mounting
Instruments required to bear verification marks shall have a verification mark support, at the place provided for above, which shall ensure the conservation of the marks.
4. Requirements for Electronic Instruments
Electronic instruments shall comply with the following re-quirements, in addition to the applicable requirements of all other paragraphs of this specifi-cation.
(1) General requirements
(i) Rated operated conditions
Electronic weighing instruments shall be so designed and manufactured that they do not exceed the maximum permissible errors under rated operating conditions.
(ii) Influence factors
An electronic instrument shall comply with the requirements of sub-paragraph (9) of paragraph 2 of this part and shall also comply with appropriate metro-logical and technical requirements at a relative humidity of 85 % at the upper limit of the temperature range.
Note: This is not applicable to an electronic in-strument of classes XI and Y(I), and of classes XII and Y(II) if e is less than 1 g.
(iii) Disturbances
Electronic instruments shall be so designed and manufactured that when exposed to disturbances, either:
(a) significant faults do not occur, i.e. the difference between the weight value indication due to the disturbance and the indication without the disturbance (intrinsic error) does not exceed 1 e; or
(b) significant faults are detected and acted upon. The indica-tion of significant faults in the display shall not be confusing with other messages that appear in the display.
Note: A fault equal to or less than the value speci-fied in clause (ix) of sub-paragraph (3) of paragraph 4 of part I, (1 e) is allowed irre-spective of the value of the error of indication.
(iv) Durability
The requirements in clause(i) of sub-paragraph(1) of paragraph 4, clause(ii) of sub-paragraph(1) of paragraph 4 and clause(iii) of sub-paragraph(1) of paragraph 4 of this part shall be met durably in accordance with the intended use of the instrument.
(v) Evaluation for compliance
A type of an electronic instrument is presumed to comply with the requirements of clause(i) of sub-paragraph(1) of paragraph, clause(ii) of sub-paragraph(1) of paragraph 4 and clause(iii) of sub-paragraph(1) of paragraph 4 of this part if it passes the examination and tests specified in Annexure A.
(vi) Application
The requirements for disturbances in clause (iii) of sub-paragraph (1) of paragraph 4 of this part shall be applied separately to:
(a) each individual cause of significant fault; and/or
(b) each part of the electronic instrument.
The choice of whether sub-clause (a) or sub-clause (b) of clause (iii) of sub-paragraph(1) of paragraph 4 of this part is applied is left to the manufacturer.
(2) Functional requirements
(i) Indications test
If the failure of an indicator shall cause a false weight value indication then the instrument shall have a display test facility which is automatically initiat-ed at switch-on of indication, e.g. display of all the relevant signs of the indicator in their ac-tive and non-active states for a sufficient time to be easily observed by the operator. This is not applicable for non-segmented displays, on which failures become evident, for example screen-displays, matrix-displays, etc.
(ii) Acting upon a significant fault
When a significant fault has been detected, the instrument shall either be made inoperative automatically or a visual or audible indication shall be pro-vided automatically and shall continue until such time as the user takes action or the fault disappears.
(iii) Warm-uptime
During the warm-up time of an electronic instrument there shall be no indication or transmission of the result of weighing, and automatic operation shall be inhibited.
(iv) Interfaces
An electronic instrument shall be equipped with interfaces permitting the coupling of the instrument to any peripheral devices or other instruments.
An interface shall not allow the metrological functions of the instrument and its measurement data to be inadmissibly influenced by the peripheral devices (for example computers), by other inter connected instruments, or by disturbances acting on the interface.
Functions that are performed or initiated via an interface shall meet the relevant requirements and conditions of paragraph 3 of this part.
Note: An “interface” comprises all mechanical, electrical and software devices at the data interchange point between an instrument and pe-ripheral devices or other instruments.
It shall not be possible to introduce into an instrument, through an interface, instructions, software programs or data intended or suitable to:
(a) display data that are not clearly defined and could be mis-taken for a weighing result;
(b) falsify displayed, processed or stored weighing results;
(c) adjust the instrument or change any adjustment factor.
An interface through which the functions mentioned above shall not be performed or initiated, need not be secured. Other interfaces shall be secured as described in clause (vi) of sub-paragraph (2) of paragraph 3 of this part.
An interface intended to be connected to a peripheral device to which the requirements of this specification apply, shall transmit data relating to primary indications in such a manner that the peripheral device shall meet the requirements.
5. Metrological Controls
(1) General
The metrological controls of instruments consist of:
(i) type /model approval;
(ii) initial verification;
(iii) subsequent verification;
(iv) In-service inspection.
(2) Type approval/Model Approval
(i) Documentation
The application for type / model approval shall include docu-mentation comprising:
(a) metrological characteristics of the instrument;
(b) a set of specifications for the instrument;
(c) a functional description of the components and devic-es;
(d) drawings, diagrams and general software information (if ap-plicable), explaining the construction and operation; and
(e) any document or other evidence that the design and con-struction of the instrument complies with the requirements of this specification.
Note: Adherence to requirements for which no test is available, such as software-based operations, shall be demonstrated by a specific declara-tion of the manufacturer (e.g. for interfaces as described in clause (iv) of subparagraph (2) of paragraph 4) of this part, and for password protected access to device-specific parameters, and setup and adjustment operations as described in clause (vi) of sub-paragraph (2) of para-graph 3) of this part.
(ii) General requirements
Type/model evaluation shall be carried out on one or more and not normally more than three instruments that represent the definitive type. If the perfor-mance of an instrument could be affected by a particular manner of operation or a particular manner of use for which conditions shall not be duplicated other than in an in-situ operation then at least one of the instruments shall be completely installed at a typical site. At least one of the instruments shall be submitted in a form suitable for laboratory simulation tests. The evaluation shall consist of the tests specified in clause (iii) of sub-paragraph (2) of paragraph 5 of this part.
(iii) Pattern evaluation
The submitted documents shall be examined and tests carried out to verify that the instru-ments comply with:
(a) the metrological requirements in paragraph 2 of this part, particularly with reference to maximum permissible errors on initial verification referred to in sub-paragraph(5) of paragraph 2 of this part using test loads described in sub-clause(a) clause(iii) of sub-paragraph(1) of paragraph 6 of this part or test loads specified by the manu-facturer;
(b) the technical requirements in paragraph 3 of this part;
(c) the requirements in paragraph 4 of this part for electronic instruments, where applicable.
The laboratory shall:
(d) conduct the tests in a manner that prevents an unnecessary commitment of resources;
(e) permit the results of these tests to be assessed for initial verification when the same instrument is involved;
(f) ensure that an instrument used in non-automatic (static) operation in accordance with clause(ii) of sub-paragraph (5) of paragraph(2) of this part, meets the weighing performance test requirements of Seventh Schedule Heading A.
(a) Operational tests
A complete instrument shall be tested:
(a) in accordance with the descriptive markings;
(b) under the normal conditions of use for which the instrument is intended; and
(c) in accordance with the test methods in paragraph 6 of this part.
The appropriate metrological authority shall require the applicant to supply test loads, equip-ment and personnel to perform the tests.
Accuracy requirements shall be applied in accordance with the appropriate parts of para-graph 2 of this part
(b) Tests and checks for compliance with technical requirements
Tests and checks shall be done on a complete instrument to assess compliance with the re-quirements for security of operation in sub-paragraph (2) of paragraph 3 of this part.
(c) Influence factor tests
Influence factors shall be applied to the complete instrument or simulator as specified in clause (v) of sub-paragraph(4) of paragraph 6 of this part and in Annexure A, in accordance with:
(a) sub-paragraph(9) of paragraph 2 of this part for all instru-ments;
(b) paragraph 4 of this part for electronic instruments.
(d) Apportioning of errors
Where modules of an instrument or system are tested separately the following requirements apply.
The error limits applicable to a module which is examined separately are equal to a fraction pi of the maximum permissible errors or the allowed variations of the indication of the complete instrument as specified in Para 2(5) of this part. The fractions for any module have to be taken for at least the same accuracy class as for the complete instru-ment incorporating the module.
The fractions pi shall satisfy the following equation:
P12+ p22 +p32+… 1
The fraction pi shall be chosen by the manufacturer of the module and shall be verified by an appropriate test, taking into account the following conditions:
(a) for digital devices pi shall be equal to 0;
(b) for weighing modules pi shall be equal to 1;
(c) for all other modules (including digital load cells), pi shall not exceed 0.8 and shall not be less than 0.3, when more than one module contributes to the effect in question.
If the metrological characteristics of the load cell or other major component have been eval-uated in accordance with the requirements Non-automatic weighing instrument that evalua-tion shall be used to aid type evaluation if so requested by the applicant.
(iv) Place of testing
Instruments submitted for type / model approval shall be test-ed at the following places:
(a) On the site at which all necessary tests shall be conducted and agreed upon between the metrological authority and the applicant;
(b) At the laboratory considered appropriate by the metrologi-cal authority;
(c) in any other suitable place agreed between the metrological authority and the applicant.
(v) Type/Model approval certificate and determination of clas-ses
The type/model approval certificate shall state the appropriate accuracy class (es), X(x) and/or Y(y), as specified at the type/model approval stage and then determined by compliance with the metrological requirements at initial verification of each instrument.
(3) Initial verification
(i) General requirements
Instruments shall be tested to verify that they comply with the metrological requirements in sub-paragraph (1) of paragraph 2- sub-paragraph (8) of paragraph 2 of this part, clause
(iii) of sub-paragraph (9) of paragraph 2 and sub-paragraph (10) of paragraph 2 of this part and the technical requirements in paragraph 3 of this part for the type of article(s) for which they are intended and when operated under normal conditions of use.
Instruments that weigh statically shall be tested in non-automatic mode provided the conditions of clause (v) of sub-paragraph (4) of paragraph 6 of this part are met.
Tests shall be carried out by the appropriate metrological au-thority, in-situ, with the instrument fully assembled and fixed in the position in which it is in-tended to be used. The installation of an instrument shall be so designed that the weighing op-eration will be the same whether for the purposes of testing or for normal operation.
(ii) Tests
Instruments shall be tested in their normal mode of
automatic operation. Tests shall be done:
(a) in accordance with the descriptive markings;
(b) under the rated conditions for which the instrument is in-tended;
(c) in accordance with the test methods given in sub-paragraph(1) of paragraph 6 of this part using test loads described in sub-clause(b) of clause(iii) of sub-paragraph(1) of paragraph 6 of this part.
The laboratory shall require the applicant to supply test loads, equipment and personnel to perform the tests.
Accuracy requirements shall be applied in accordance with the appropriate part(s) of subparagraph (5) of paragraph 2 of this part.
The metrological authority shall conduct the tests in a manner that prevents an unnecessary commitment of resources. In appropriate situations and to avoid duplicating tests previously performed on the instrument for type evaluation under sub-clause (a) of clause (iii) of sub-paragraph (2) of paragraph 5 of this part, use the results of observed tests for initial verifica-tion.
(iii) Conduct of the test
The laboratory:
(a) shall conduct the tests in a manner that prevents an unnec-essary commitment of resources;
(b) shall, where appropriate and to avoid duplicating tests pre-viously done on the instrument for type/model evaluation under sub-clause(a) of clause(iii) of sub-paragraph(2) of paragraph of this part, use the test results from type/model evaluation for initial verification.
(iv) Determination of accuracy class
(a) Category X instruments
For category X instruments the metrological authority shall:
(I) apply the accuracy class requirements for the product(s) used in the tests in accordance with the appropriate parts in sub-clause(a) of clause(i) of sub-paragraph(2) of paragraph 5 of this part for initial verification.
(II) Verify that:
the accuracy classes marked in accordance with sub-pa rag rap h(1 1 )of paragraph 3 of this part are the same as the accuracy class determined as above; and
the designated accuracy class factor (x) marked in accordance with s u b-paragraph(11)of paragraph 3 of this part is greater than or equal to the factor (x) de-termined as above under (A).
(b) Category Y instruments
For category Y instruments the metrological authority shall ap-ply the requirements for the accuracy class marked in accordance with the appropriate parts specified in sub-clause (b) of clause (i) of sub-paragraph (5) of paragraph 2 of this part.
(4) Subsequent metrological control
(i) Subsequent verification
Subsequent verification/Re-verification shall be carried out in accordance with the same provisions as in sub-paragraph (3) of paragraph 5 of this part for ini-tial verification.
(ii) In-service-Inspection
In-service inspection shall be carried out in accordance with the same provisions as in sub-paragraph (3) of paragraph 5 of this part for initial verification, with the exception that the in-service maximum permissible errors shall be applied.
6. Test Methods
(1) Automatic operation
(i) Values of the mass of test loads
Test loads shall be applied as follows:
(a) test load values close to Min and Max;
(b) test load values close to, but not above, two critical points in between Min and Max.
Note: To achieve the maximum rate of operation specified for the instrument it shall be necessary to use more than one test load at each of the four nominal values above.
(ii) Number of test weighings
The minimum number of consecutive test weighings taken and used to determine the mean error and the standard deviation of the error for category X instruments, or the individual errors for category Y instruments, shall be as specified in Table 7.
Table7
| Category | Load | Number of test weighings |
| (1) | (2) | (3) |
| X | m 1 kg | 60 |
| 1kg <m 10 kg | 30 | |
| 10kg<m 20kg | 20 | |
| 20kg<m | 10 | |
| Y | Minimum of 10 for any load | |
Note: For category Y instruments the number of test weighings shall be at least ten unless a special test procedure is specified in the type/model approval certificate.
(iii) Types of test load
(a) Type/model approval
Test loads shall be used which comply with the following conditions:
(I) appropriate dimensions;
(II) constant mass;
(III) solid, non-hygroscopic, non-electrostatic, non-magnetic material;
(IV) metal-to-metal contact shall be avoided.
(b) Initial verification, subsequent verification and in-service inspection Test load shall be the type of article(s) which are intended to be used.
(iv) Conditions of tests
The load transport system shall be set to its maximum speed, and if adjustable by the opera-tor, also at a speed approximately midway through the operating range. If the speed is related to a particular product, the speed shall be set to the preset speed for that product.
Zero shall be set at the start of each test sequence at a given load value.
(v) Control instrument
A control instrument for determining the conventional true value of the mass of each test load shall be available for testing. The control instrument shall either be separate (an instrument other than the instrument being verified) or integral.
(a) Accuracy of control instruments
The control instrument, whether separate or integral, shall ensure the determination of the conventional true value of the mass of each test load to an accuracy of at least one-third of whichever is the smaller of the appropriate maximum permissible errors for automatic weigh-ing in Tables 3 and 4, for category X instruments, and one-third of the appropriate maximum permissible errors in Table 5 for category Y instruments.
(vi)Conventional true value of the mass of the test load
The conventional true value of the mass of each test load shall be determined using either the separate or the integral control instrument described in sub-clause(a) of clause(v) of sub-paragraph(1) of paragraph 6 of this part as appropriate.
(vii) Individual errors of weighings
(a) Category X
The individual errors of weighings shall be the difference between the conventional true value of the mass of the test load as described in of clause (vi) of sub-paragraph (1) of paragraph 6 of this part and the indicated or printed weight value observed and recorded
(b) Category Y
The individual errors of weighings shall be the difference between the conventional true value of the mass of the test load as described in clause (vi) of sub-paragraph (1) of paragraph 6 of this part and the indicated or printed weight value observed and recorded.
To eliminate the effect of rounding error during testing, one of the following shall be used:
(I) the scale interval, d, shall be ≤ 0.2 e;
(II) the mass of the test load shall be selected using the proce-dure in sub-clause(b) of clause(ii) of sub-paragraph (9) of paragraph 3 of Annexure A].
Note: Where the procedure in sub-clause (b) of clause (ii) of sub-paragraph (9) of paragraph 3 of Annexure A is used it will not be possible to record the individual errors. It will suffice, however, to note whether or not the instrument is within the maximum permissible errors in Table 5.
(viii) Indicated weight for category X instruments
For category X instruments, indications and/or printouts of the weight values (or the difference between the weight value and a nominal set-point) shall be provided for each load for deter-mining the mean error and the standard deviation of the error for each test. For this purpose the scale interval, d, shall not be greater than the appropriate limit for Table 4 mul-tiplied by the class designation factor (x).
Alternatively, other practical means for demonstrating compliance with Tables 3 and 4 shall be provided by agreement with the metrological authority. For example, where suitable facili-ties for directly performing these calculations exist within the instrument under test, these shall be used provided that they are checked for accuracy before use. In this situation it is not mandatory that the individual weight values are recorded. No specific method of verifying that the instrument meets the calculation requirements is given, since the method used will de-pend on the particular design being tested. However, any methods used shall demonstrate that the correct errors are being calculated as specified in sub-clause (a) of clause (vii) of sub-paragraph (1) of paragraph 6 of this part, the correct formulae as specified in clause (v) of sub-paragraph (3) of paragraph 4 and clause (vi) of sub-paragraph (3) of paragraph 4 of part I are being used for the calculations in the instrument, and shall include at least some checks with loads. Details of the method used shall be recorded in the appropriate place in the type evalu-ation report.
(2) Non-automatic (static) operation
(i) Verification standards
The error of the standard test weights or masses used shall not be greater than one-third of the maximum permissible error for the load as specified in Table 6.
(ii) Values of the mass of the test load
Test loads shall be applied as specified for each individual test in Annexure A.
(iii) Number of weighings
The number of test weighings at each test load shall be one.
(iv) Test weights indication
For non-automatic (static) operation the instrument shall be provided with:
(a) a static ‘live’ weight indication; or
(b) a continually updated weight indication by simulation of the weighing cycle.
For determining the individual errors, the scale interval, d, shall be ≤ 0.2 e or, alternatively, the procedure described in clause (ii) of sub-paragraph(10) of paragraph 3 of Annexure A shall be used.
(3) Status of automatic correction facilities
The status of dynamic adjustment and automatic zeroing facili-ties shall be as specified for each individual test in Annexure A.
(4) Mode of operation for testing
(i) Span stability testing [clause (iii) of sub-paragraph(5) of par-agraph 6 of this part]
For span stability testing the instrument shall be tested in non-automatic (static) operation. A single static test load near maximum capacity shall be used.
(ii) Disturbance testing
For disturbance testing the instrument shall be tested in non-automatic (static) operation. Each test shall be performed with one small static test load.
(iii) Warm-up test[ sub-paragraph(2) of paragraph 5 of Annexure A]
The warm-up test shall be performed in non-automatic (static) operation. A single static test load near maximum capacity shall be used.
(iv) Eccentricity [sub-paragraph (6) of paragraph 5 of Annexure A]
For instruments that weigh dynamically in automatic opera-tion, the effect of eccentric loading shall be determined in automatic operation using a test load of 1/3 Max (plus the additive tare capacity, if applicable) using the portion of the load transport system that is halfway between the center and the back, and repeated with the same test load using the portion of the load transport system that is halfway between the cen-ter and the front.
For instruments that weigh statically in automatic operation, the effect of eccentric loading shall be determined in non-automatic (static) operation with a test load of 1/3 Max (plus the additive tare capacity, if applicable) located in the center [Para 5(7)(ii) of Annexure A] and in each of the four quarter segments of the stationary load transport system.
On an instrument with a load transport system having n points of support, with n > 4, the fraction 1/(n – 1) of Max (plus the additive tare capacity, if applicable) shall be applied to each point of support.
(v) Influence factor tests
The mode of operation required for influence factor tests shall be decided as follows.
All instruments designed to weigh loose material shall be test-ed in non-automatic (static) operation. All tests with loads greater than or equal to 20 kg shall be done in non-automatic (static) operation.
For instruments that weigh pre-assembled discrete loads dy-namically, the mode of operation for influence factor tests shall be as specified for each indi-vidual test in Annexure A.
For instruments that weigh pre-assembled discrete loads stat-ically, the mode of operation for influence factor tests shall be as specified for each individual test in Annexure A or shall be decided on by the procedure of sub-clause (a) of clause (v) of sub-paragraph(4) of paragraph 6 of this part.
(a) Option for non-automatic (static) testing
As an alternative to automatic operation during influence fac-tor testing, static test loads shall be applied in a non-automatic (static) operation provided that:
- the instrument weighs statically in normal operation;
- the test of sub-clause (b) of clause (v) of sub-paragraph(4) of paragraph 6 of this part has demonstrated that random errors are not significant in normal operation; and
- where a decision is made to test in non-automatic (static) operation this shall be applied to all the influence factor tests and recorded in the test report.
(b) Determination of random errors for instruments that weigh statically
To determine whether static loads shall be used for influence factor testing, the following test shall be applied before approval testing takes place: automat-ic test weighings, as specified in sub-paragraph (1) of paragraph 6 of this part, shall be applied to the instrument under normal conditions of use for Min and Max load values and for the load transport system set to its maximum speed of operation and also approximately midway through the operating speed range.
Static loads shall be used for influence factor testing where the results of these tests demonstrate that, for the test loads, the differences between the results of several weighings of the same load are not greater than the absolute value of the maximum permissible error of the instrument for that load given in Table 6 for initial verification.
(5) Examination and tests of electronic instruments
The examination and testing of an electronic weighing instru-ment is intended to verify compliance with the applicable requirements of this specification and especially with the requirements of paragraph 4 of this part.
(i) Examination
An electronic weighing instrument shall be examined to obtain a general appraisal of its design and construction.
(ii) Performance test
An electronic weighing instrument or electronic device, as ap-propriate, shall be tested as specified in Annexure A to determine the correct functioning of the instrument.
Tests are to be carried out on the whole instrument except when the size and/or configuration of the instrument does not lend itself to testing as a unit. In such cases the electronic devices shall be tested, where possible as a simulated instrument including all electronic elements of a system which shall affect the weighing result. In addi-tion, an examination shall be carried out on the fully operational weighing instrument.
Susceptibility that would result from the use of electronic in-terfaces to other equipment shall be simulated in the tests.
(iii) Span stability test
The span stability test shall be conducted as described in paragraph 7 of Annexure A, applying the requirements given in sub-paragraph (10) of paragraph 2 of this part.
ANNEXURE A
(Mandatory)
Testing procedures for automatic catch weighing instruments
1. Examination for type/model approval
(1) Documentation (clause (i) of sub-paragraph (2) of paragraph 5 of part II)
Review the documentation that is submitted, including neces-sary photographs, drawings, diagrams, general software information, relevant technical and functional description of main components, devices, etc. to determine if it is adequate and correct. Consider the operational manual.
(2) Compare construction with documentation
Examine the various devices of the instrument to ensure com-pliance with the documentation.
(3) Metrological characteristics
The metrological characteristics shall meet the requirements according to the Part I of this specification.
(4) Technical requirements [paragraph 3 of part II]
Examine the instrument for conformity with the technical re-quirements according to the Part II of this specification,
(5) Functional requirements [sub-paragraph (2) of paragraph 4 of part II]
Examine the instrument for conformity with the functional re-quirements according to the Part II of this specification.
2. Examination for initial verification
(1) Compare construction with documentation
Examine the instrument for conformity with the approved type.
(2) Descriptive markings
Check the descriptive markings according to the part II of this specification.
3. General test conditions
(1) Voltage supply
Power-up the equipment under test (EUT) for a time period equal to or greater than the warm-up time specified by the manufacturer and maintain the EUT energized for the duration of the test.
(2) Zero-setting
Adjust the EUT as closely as practicable to zero prior to each test and do not readjust at any time during the test, except to reset if a significant fault has oc-curred.
The status of automatic zero facilities shall be as specified for each test.
(3) Dynamic setting
Dynamic setting shall be done in accordance with the manu-facturer’s instructions prior to commencing the tests.
Before commencing influence factor tests, dynamic setting shall be repeated for each load value and thereafter shall not be repeated.
Dynamic setting shall not be repeated during disturbance tests except after a significant fault.
If the dynamic setting process is part of a calibration proce-dure for the whole weighing range then the dynamic setting shall not be repeated before test-ing with different load values.
(4) Static test loads
Static test loads shall be used for the influence factor testing in sub-paragraph (2) of paragraph 6 of Annexure A for machines designed to weigh loose materi-al. For machines that weigh statically, where the conditions in clause (v) of sub-paragraph (4) of paragraph 6 of part II are met (including a test applied before the testing in sub-paragraph (2) of paragraph 6 of Annexure A commences) static test loads shall optionally be used.
(5) Temperature
Except for the temperature test [clause (v) of sub-paragraph (4) of paragraph 6 of Annexure A)] and the humidity test [clause (iii) of sub-paragraph (2) of para-graph 6 of Annexure A], the tests shall be performed at a steady ambient temperature, usually normal room temperature unless otherwise specified. The temperature is deemed to be steady when the difference between the extreme temperatures noted during the test does not exceed one-fifth of the temperature range of the instrument without being greater than 5 °C, and the rate of change does not exceed 5 °C per hour.
The handling of the instrument shall be such that no condensa-tion of water occurs on the instrument.
(6) Recovery
After each test, allow the instrument to recover sufficiently before the following test. (7) Preloading Before each weighing test, the instrument shall be pre-loaded to Max, except for the tests in sub-paragraph (2) of paragraph 5 of Annexure A (warm-up) and clause(ii) of sub-paragraph (2) of paragraph 6 of Annexure A (temperature effect on no-load).
(7) Multiple range instrument
In principle, each range shall be tested as a separate instru-ment.
(9) Evaluation of error in automatic operation
(i) Category X
For category X instruments, indications and/or printouts of the weight values (or the difference between the weight value and a nominal set-point) shall be provided for each load for determining the mean error and the standard deviation of the error. With the scale interval, d, the MPME and MPSD shall be calculated for the number of individual loads defined in clause (ii) of sub-paragraph (1) of paragraph 6 of Part II.
Alternatively, other practical means for demonstrating compli-ance with Tables 3 and 4 shall be provided by agreement with the metrological authority as described in clause (viii) of subparagraph (1) of paragraph 6 of Part II.
(ii) Category Y
(a)Indication with a scale interval not greater than 0.2 e
If an instrument with digital indication has a device for display-ing the indication with an actual scale interval, d 0.2 e, this device shall be used to determine the error. When the device is used it shall be noted in the Test Re-port.
(b) Indication with a scale interval greater than 0.2 e
The rounding error included in any digital indication shall be eliminated if the actual scale interval, d, is greater than 0.2 e. This shall be accomplished by one of the following methods:
(I) if possible, the mass of the test load shall be selected to eliminate the rounding error:
if the maximum permissible error = 1.5 e (or 0.5 e, 2.5 e, etc.) the value of the mass of the test load shall be selected as close as possible to a whole scale interval;
if the maximum permissible error = 1.0 e (or 2.0 e, 3.0 e, etc.) the mass of the test load shall be selected as close as possible to a whole scale interval plus (or minus) 0.5 e.
or:
(c) If ( I) is not applicable, the rounding error shall be taken into consideration by adding an additional 0.5 e to the maximum permissible errors specified in Table 5.
(10) Evaluation of error in non-automatic (static) operation
(i) Indication with a scale interval not greater than 0.2 e If an instrument with digital indication has a device for displaying the indication with d 0.2 e, this device shall be used to determine the error. If a device is used it shall be noted in the Test Report.
(ii) Use of standard weights to assess rounding error
(a) General method to assess error prior to rounding
For instruments with digital indication having scale interval, e, changeover points shall be used to interpolate between scale intervals, i.e. to determine the indication of the instrument, prior to rounding, as follows.
At a certain load, L, the indicated value, I, is noted. Additional weights of say 0.1 e are successively added un-til the indication of the instrument is increased unambiguously by one scale interval (I + e). The additional load, ∆L, added to the load receptor gives the indication, P, prior to rounding by using the following formula:
P = I + 0.5 e – ∆L
The error prior to rounding is: E = P – L = I + 0.5 e – ∆L – L
Example: An instrument with a scale interval, e, of 5 g is loaded with 1 kg and thereby indicates 1 000 g. After adding successive weights of 0.5 g, the indication changes from 1 000 g to 1 005 g at an additional load of 1.5 g. Inserted in the above formula these observations give:
P = (1 000 + 2.5 – 1.5) g = 1001 g
Thus, the true indication prior to rounding is 1001 g, and the er-ror is:
E = (1001 – 1000) g = +1 g
(b) Correction for error at zero
Evaluate the error at zero load, E0, and the error at load L, E, by the method of sub-clause
(a) of clause (ii) of sub-paragraph (10) of paragraph 3 of Annex-ure A. The corrected error prior to rounding, Ec, is:
Ec = E – E0
Example: If, for the example in Para 3(10)(ii)(1a) of Annexure A, the error calculated at zero load was:
E0 = +0.5 g,
the corrected error is: Ec = +1 – (+ 0.5) = +0.5 g
4. Test program
(1) Type/model evaluation [clause (iii) of sub-paragraph (2) of paragraph 5 Part II]
paragraph 1 and paragraph 5 to 7 of Annexure A shall normally be applied for type evaluation, using the test methods detailed in paragraph 6.
4(2) Initial verification [sub-paragraph (3) of paragraph 5 of part II]
For initial verification, paragraphs 2 and 5 of Annexure A, except for sub-paragraph (2) of para-graph 5 of Annexure A (warm-up) and clause (ii) of sub-paragraph (4) of paragraph 5 of Annex-ure A (range of zero- setting) shall be applied. For instruments mounted on vehicles, clause (viii) of sub-paragraph (2) of paragraph 6 of Annexure A shall also be applied.
The types of test loads used shall comply with clause (iii) of sub-para-graph (1) of paragraph 6 of part II.
5. Metrological performance tests
(1) General
(i) Standard operational test for automatic operation
The test procedure shall be as follows:
a) Start the automatic weighing system, including (if the EUT is installed in the place of use) the surrounding equipment which is normally operational when the instrument is in use.
b) Set the load transport system to its maximum speed of op-eration
c) Except where stated, select four test loads which must in-clude values close to Min and Max and at values close to, but not above, two critical points clause (vi) of subparagraph (2) of paragraph 3 of Part I in between Min and Max. More than one test load shall be required for each of the above load values to achieve the maximum rate of operation. Weigh the test loads on the control instrument specified in sub-clause (a) of clause (v) of sub-paragraph (1) of paragraph 6 of part II to determine the conventional true value of each test load as specified in clause (vi) of sub-paragraph (1) of paragraph 6 of part II.
d) The number of test weighings for each load depends on the mass of the test load as specified in clause (ii) of sub-paragraph (1) of paragraph 6 of part II.
e) Enable the test loads to be automatically weighed for the specified number of times and record each indication. Determine the individual errors of weighing in accordance with:
(I) sub-clause (a) of clause (vii) of sub-paragraph (1) of para-graph 6 of part II for category X instruments;
(II) sub-clause (b) of clause (vii) of sub-paragraph (1) of para-graph 6 of Part II for category Y instruments.
f) Determine the mean error [ clause (v) of sub-paragraph (3) of paragraph 4 of Part I] and the standard deviation of the error [clause (vi) of sub-paragraph (3) of paragraph 4 of Part I] for category X instruments in accordance with clause (viii) of subparagraph (1) of paragraph 6 of part II, or the individual errors for category Y instru-ments.
The standard operational test is used for a number of different tests:
(I) dynamic setting;
(II) eccentricity for dynamic weighing instruments;
(III) static temperatures;
(IV) temperature effect on no load indication;
(V) voltage variation;
(VI) operational tests.
(VII) Weighing performance test for non-automatic (static) op-eration
The following weighing test shall be performed in non-automatic (static) operation as an alter-native to automatic operation during influence factor testing, provided the conditions of clause (v) of sub-paragraph (4) of paragraph 6 of Part II are met.
Apply test loads from zero up to and including Max, and similarly remove the test loads back to zero. When determining the initial intrinsic error, at least ten different test loads shall be se-lected, and for other weighing tests at least five shall be selected. The test loads selected shall include Max and Min, and at values close to, but not above, those at which the maximum per-missible error changes.
It shall be noted that when loading or unloading weights, the load shall be progressively in-creased or decreased.
If the instrument is provided with an automatic zero-setting or zero-tracking device, it shall be in operation during the tests, except for the temperature test. The error at zero point is then determined according to sub-clause (a) of clause (ii) of sub-paragraph (10) of paragraph 3 of Annexure A.
(iii) Supplementary weighing test
For instruments with an initial zero-setting device with a range greater than 20 % of Max, a supplementary weighing test shall be performed using the upper limit of the range as zero point.
(2) Warm-up
This test is to verify that metrological performance is maintained in the period immediately after switching on. The method is to check that automatic operation is inhibited until a stable indication is obtained and to verify that zero and span errors comply with the requirements during the first 30 minutes of operation. Zero-tracking and automatic zero-setting shall be dis-abled, unless the zero- setting operates as part of every automatic weighing cycle. In this case this function shall be enabled or simulated as part of the test.
Other test methods which verify that metrological performance is maintained during the first 30 minutes of operation shall be used.
1) Disconnect the instrument from the supply for a period of at least eight hours prior to the test.
2) Reconnect the instrument and switch on while observing the indication.
3) Check that it is not possible to initiate automatic weighing until the indicator has stabilized.
4) As soon as the indication has stabilized, set the instrument to zero if this is not done automatically.
5) Determine the error at zero by the method of sub-clause (a) of clause (ii) of subparagraph (10) of paragraph 3 of Annexure A, and specify this error as E0I (error of initial zero-setting) at first and as E0 (zero-setting error) when repeating this step.
6) Apply a static load close to Max. Determine the error by the method of sub- clause (a) of clause (ii) of sub-paragraph (10) of paragraph 3 and sub-clause (b) of clause (ii) of sub-paragraph (10) of paragraph 3 of Annexure A.
7) Verify that:
(I) the zero indication error, E0I, is not greater than 0.25 e
(II) the span error is not greater than the maximum permissible error specified in Table 6 for initial verification.
8) Repeat steps 5) and 6) after 5, 15 and 30 minutes.
9) After each time interval verify that:
(I) the zero variation error, E0 – E0I, is not greater than 0.25 e × pi;
(II) the span error is not greater than the maximum permissible error specified in Table 6 for initial verification.
(3) Range of dynamic setting
(i) Range
If the dynamic setting facility is specified for a limited weighing range (or ranges) then the standard weighing test shall be done at load values close to the lim-its of the range for at least one of the nominal load values specified in clause (i) of sub-paragraph (1) of paragraph 5 of Annexure A.
(ii) Out of range interlock
If the dynamic setting facility is specified for a limited weighing range (or ranges) then it shall be verified that operation and print out outside of the specified range is inhibited, by attempting to weigh loads that are close to but outside the range.
(4) Zero-setting
(i) Modes of zero-setting
To test the automatic zero-setting device it is necessary to al-low the instrument to operate through the appropriate part of the automatic cycle and then to halt the instrument before testing.
The range and accuracy of zero-setting shall be tested by ap-plying loads as specified below in non- automatic (static) operation to the load receptor after the instrument is halted.
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