This regulation applies to the initial verification, subsequent verification and in-use inspection of mechanical lever balances (hereinafter referred to as balances). JJG 98-2006 Verification Regulation for Mechanical Balances JJG98-2006 Standard download decompression password: www.bzxz.net
This regulation applies to the initial verification, subsequent verification and in-use inspection of mechanical lever balances (hereinafter referred to as balances).

Verification Regulation of the People's Republic of China JJG 98—2006
Mechanical Balance
2006-09-06 Issued
2007 —03-06 Implementation
The General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China issued JJG 98—2006
Verification Regulation
for Mechanical Balance
JJG 98--2006
Replaces JJG98—1990
(Mechanical Balance Part)
This regulation was approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on September 6, 2006 and came into effect on March 6, 2007 H implementation,
Responsible unit: National Technical Committee on Mass Density Metrology Main drafting unit: China Institute of Metrology Participating drafting unit: Hubei Institute of Metrology and Testing Technology Dalian Metrology Verification and Testing Institute
China Astronaut Research and Training Center
Shanghai Precision Scientific Instrument Co., Ltd.
Shanghai Liangping Instrument Co., Ltd.
National Railway Weighing and Measuring Station
Shaanxi Institute of Metrology
Xi'an Institute of Metrology and Testing
This regulation is entrusted to the National Technical Committee on Mass Density Metrology to interpret this regulation Main drafter:
Li Zhanhong
Liu Jianming
Participating drafter:
Ding Junping
Gao Changlv
Xu Qianyu
Tao Xuejun
JJC 98—2006
(China Institute of Metrology)
(China Institute of Metrology)
(Hubei Institute of Metrology and Testing Technology) (Dalian Metrology Verification and Testing Institute)
(China Astronaut Research and Training Center)
(Shanghai Precision Scientific Instrument Co., Ltd.) (Shanghai Liangping Instrument Co., Ltd.) (National Railway Weighing and Measuring Station)
(Shaanxi Institute of Metrology)
(Xi'an Institute of Metrology and Testing)
2 Overview·
3 Performance Requirements
3.1 Accuracy level..
3.2 Metrological performance of balance-
General technical requirements
Appearance and technical requirements
4.2 Working environment conditions
Control of measuring instruments...
Verification conditions,
Verification items
Verification methods·
Processing of verification results·
Verification cycle
Appendix A Verification record format for double-pan large balance
Appendix R Verification record format for single-pan large balance
JJG 98—2006
Appendix C Format of the combined error calibration record of mechanical pinch-base balance
Appendix Format of the inner page of the calibration certificate of the balance (differential scale or digital scale balance) Appendix E Format of the inner page of the calibration certificate of the balance (ordinary scale balance) (1)
JJG 98—2006
Verification procedures for mechanical balances
This procedure refers to the international recommendation of the International Organization for Legal Metrology (OIML) R76 Non-automatic weighing instruments (non-automatic weighing instruments) in terms of accuracy level and technical terms. 1 Scope
This procedure applies to the initial calibration, subsequent calibration and in-use inspection of mechanical lever balances (hereinafter referred to as balances).
2 Overview
A balance is a measuring instrument that uses the principle of lever balance to determine the mass of an object. The main structure of the mechanical lever balance is composed of the bottom plate, outer cover, column brake mechanism, crossbeam, hanging system, reading system, damping part, mechanical hanging weight device, vernier scale, chain scale, transmission device and other components. With the help of the base weight, the weight of the object is directly measured by the lever balance principle. This balance is used for mass value transfer, object mass and volume measurement, and has been widely used in electronics, textiles, metallurgy, chemical industry, agriculture, health, scientific research units and colleges and universities. 3 Metrological performance requirements
3.1 Accuracy level
3.1.1 The large balance is divided into one of the following accuracy levels according to its calibration scale division value e and calibration scale division number n (the ratio of the maximum weighing to the calibration scale division value e): Special accuracy level
High accuracy level
Symbol is CD
Symbol is CID
The relationship between the accuracy level of the balance and e and n is shown in Table 1. Table 1 Relationship between accuracy level of balance and e, n Accuracy level
Special accuracy level
High accuracy level
Verification scale division value e
10pgse n500μg
Imgsse
Verification scale division number n
5×10*
5×104
1×102
Unlimited
1×105
1×10%
Minimum weighing
3.1.2 Division of balance levels;
JJG 98—2006
Mechanical lever balances belonging to level D and level ID are divided into accuracy levels as shown in Table 2 according to the division number of the verification scale.
Table 2 Accuracy levels of balances
Accuracy level symbol
3.1.3 Classification of balances
Division of calibration scale1
1×10m
5 × 10≤n<1× 10
2 × 10 ≤n<5×10g
1 × 10°n<2× 106
5× 10n<1×106
2 ×10≤n<5×10
1 × 10n<2×105
5 ×10≤<1×105
2 ×10≤n<5× 10*
1×10°≤n<2×10t
Mechanical lever balances can be divided into double-pan balances and single-pan balances according to their structure. They can also be divided into differential scale balances, digital scale balances and ordinary scale balances according to their scale classification. 3.1.4 Verification scale graduation value
3.1.4.1 The verification scale graduation value e of a balance is expressed in mass units and shall be in the following form: 1 × 10* or 2 × 10″ or 5 × 10° Where: is a positive integer, a negative integer or zero. Other forms are allowed for balances in use. 3.1.4.2 For balances with scales but no micro-reading mechanism, the verification scale graduation value e is equal to the actual scale graduation value d. 3.1.4.3 For balances with scales and micro-reading mechanism, the verification scale graduation value e is selected by the manufacturer according to Table 1 and the following rules:
de 10d
3.2 Metrological performance of large balances
3.2.1 The indication repeatability of the balance, the verification scale graduation value error, the unequal arm error of the crossbar, and the weighing error of the vernier scale and chain scale shall comply with the provisions of Table 3. 2
Repeatability
Accuracy level
(division)
JJG 98—2006
Table 3 Maximum allowable error of metrological performance of balance Calibration scale division value error
Differential
Scale or digital scale balance with damper
(division)
Empty scale error and full scale
Error||Subsequent calibration
First calibration
Full scale
+ 2f - 1
Calibration and in-use
+ 1/ - 2
Full scale
Ordinary scale
Balance/mg
Left pan! Empty scale
Beam unequal arm error (division)
Differential scale or digital scale with damper
Subsequent inspection
Determination and convenient inspection
Ordinary scale
Vernier scale
Code scale
Weighing error (division)
1 The division value error of differential scale or digital scale balance with damper is measured by the swing amplitude from the zero position of differential scale or digital scale to the end of formal division.
2 The tolerance of the division value error of ordinary scale balance: measured by the maximum actual division value: the maximum actual division shall not be greater than the nominal scale division value:
3 The division value shall not be greater than 0.001mg Tianli, the error of the vernier scale is not greater than 2 divisions: 4 For a balance equipped with a micro-reading machine, if the repeatability of the indication is not greater than 1 division of the mechanism, and the other metrological performances also meet the corresponding proportional relationship with the division value of this mechanism, the accuracy level of the balance can be determined according to the division value of the micro-reading mechanism. 3.2.2 For a balance with a mechanical weight adding and weight subtraction device, the error of the weight combination shall not be greater than the provisions of Table 4. Table 4 Maximum allowable error of Guima combination
Verification scale division value/mg
0.05e<0.2
0.01≤e<0.05
Milligram group
Maximum allowable error of weight combination (division) Gram group
Note: For a balance with a mechanical weight adding device, the weight should be hung on the weight adding device of the balance for verification. The maximum permissible error of the calibration result shall not be greater than the sum of the combined error of the corresponding hanging base weight and the corresponding cross-dye unequal robustness error. 3
4 General technical requirements
4.1 Appearance and technical requirements
JJG 98—2006
4.1.1 The nameplate of the balance shall have the model, product name, factory number, manufacturer name, maximum weighing capacity, minimum weighing capacity, calibration scale graduation value, factory date, accuracy level (indicated by an oval and Roman numerals inside the oval, plus a digital subscript), manufacturing measuring instrument license mark and number, etc. The nameplate of the balance must be eye-catching, firm, and not easily damaged or disassembled.
4.1.2 The surface plating or coating of the balance: the color should be uniform, and there should be no exposed bottom, peeling, layering, blistering, fluffing, water stains, burrs, spots, cracks, and obvious scratches and abrasions. 4.1.3 The installation of the foot screws should ensure that the balance is placed stably, and the fit between the screws and nuts should be moderately tight to facilitate the adjustment of the balance. The outer cover of the balance should be tight and without obvious gaps. The front door and side doors should be easy and flexible to open and close. 4.1.4 The brake mechanism of the balance should be stable and should not cause any problems with any parts of the balance. There should be no defects such as self-falling and jamming. When the balance is turned on or off, the beam shall not be twisted, swung, the needle carried, skipped, or the ear folded, and the weighing pan shall not be continuously shaken.
4.1.5 For optical mechanical balances with differential scales, the scale lines of the differential scale in the projection window shall be clear and without obvious skew. The width of the reading sight line shall not be greater than the scale line width of the differential scale visible in the projection window, and the sight line shall be parallel to the scale lines of the scale.
4.1.6 For ordinary scale balances, the scale scale interval shall not be less than 1mm, the width of the pointer needle tip shall not be greater than the scale line width, the pointer shall be parallel to the scale lines, and the needle tip shall be able to cover 1/3 to 3/4 of the total length of the short scale line when the balance swings: the color of the needle tip shall be significantly different from the scale lines. 4.1.7 The beam and knife of the balance shall not have burrs, cracks or obvious sand holes. For balances with accuracy of I1~(D2), there shall be no obvious light transmission after the knife and the working surface of the knife are in contact; for balances with accuracy of D2~ID2, the light transmission after the knife and the working surface of the knife shall not be less than 1/5 of the total length of the knife. 4.1.8 Balances with magnetic code hanging devices must be able to ensure that the actual hanging code taken and placed is consistent with the displayed value of its hanging code device, and there shall be no phenomenon such as the hanging code not falling into the groove, not falling into the correct position or serious shaking of the hanging code: the arrangement height of the hanging code rod and hook and the height of each drop shall be consistent. During the operation of the balance, the hanging code shall not collide or rub with the stationary parts of the balance, so as to hinder the normal swing and Readings. 4.1.9 For detachable parts of the same shape and symmetrically placed, except for those that are completely interchangeable, the balance bracket, support leaf, weighing pan, pan holder, lifting lug, damper and other parts of the same shape and symmetrically placed should be marked with the distinguishing marks of left "." or "1" and right ".." or "2" respectively. 4.1.10 For balances with dampers, the time from swinging to rest should not be more than 2 cycles. For balances without dampers (except chain code balances), the damping reduction coefficient when empty and fully weighed should not be greater than 1.25. 4.1.11 Mechanical lever balances should be equipped with sensitivity and balance position adjustment devices. 4
JJG 98-—2006
4.1.12 Under normal use conditions, the reading of the balance measurement result must be reliable, easy to read and clear. The parallax of the reading shall not be greater than 0.2·calibration scale graduation value: 4.1.13 For a balance with a level or a weight, it should be possible to ensure that the bubble is centered or the tips of the upper and lower weights of the leveling weight are opposite to each other through the adjustment of the balance's horizontal adjustment screw, and remain within the range of 1mm~3mm. At this time, the balance should be able to operate normally. www.bzxz.net
4.2 Working environment conditions
4.2.1 Temperature and relative humidity
The balance should be able to operate normally at least under the temperature and relative humidity conditions specified in Table 5, so that its metrological performance does not exceed the relevant provisions of Table 3 and Table 4.
Table 5 Working environment conditions
Accuracy level
CD, -D,
e>0.001mg
Maximum weighing capacity>1kg
,-D.
aD. D1o
4.2.2 Vibration and airflow
18 --23
10--32
Temperature fluctuation is not greater than! (/h)
There is no vibration and airflow around the balance that may affect the balance's metrological performance. 4.2.3 Time
The degree is not greater than! (
When the balance is calibrated under the conditions of 4.2.1 and 4.2.2, in strict accordance with the calibration items, operating procedures and steps specified in the calibration regulations, the balance shall not have metrological performance exceeding the tolerance due to the calibration time. 4.2.4 There is no corrosive gas in the air around the balance. 4.2.5 The balance should be placed on a stable and firm platform for use. 5 Measuring instrument control
Measuring instrument control includes: initial calibration, subsequent calibration and in-use inspection. 5.1 Verification conditions
5.1.1 Verification standards
5.1.1.1 Codes
1) A set of standard magnetic codes of corresponding grade shall be provided, and the expanded uncertainty of the codes shall not be greater than 1/3 of the maximum allowable error of the tested balance under the load. 2) For the verification of equal-arm balances, a pair of equal-weight magnetic codes equivalent to the maximum weighing capacity of the balance shall also be prepared. 5
5.1.1.2 Other related measuring instruments
1) Level for measuring the level of the balance.
JJG 98—2006
2) Thermometer with a graduation value not greater than 0.2°. 3) Hygrometer with a relative accuracy not greater than 5%. 5.1.2 Verification environment conditions
5.1.2.1 Temperature and humidity of the verification room
The temperature and humidity of the verification room shall meet the requirements of Table 5. 5.1.2.2 The calibration room shall not be affected by vibration, airflow and other strong magnetic fields. 5.1.2.3 The room shall be kept clean, with a moderate area and shall not be overcrowded. 5.1.2.4 The balance workbench shall be flat, stable, with good rigidity and certain shockproof and seismic isolation effects. 5.1.2.5 Power supply
The balance working with the power supply shall be within the following power supply variation range: for 220V power supply, the voltage variation shall be -15% to +10%; for 50Hz power supply, the frequency variation shall be -2% to +2%. 5.1.2.6 The balance and scale in the calibration room shall be kept away from direct sunlight as much as possible. 5.1.2.7 The calibration of the balance shall generally be based on the principle of calibration under the operating environment conditions. 5.1.3 Cleaning of the balance before calibration
The balance shall be cleaned before formal calibration. Carefully remove dust from all parts of the balance and debris left over from the packaging. The knife and the knife holder should be properly cleaned with a clean and soft magic leather or a soft brush, or with a clean and soft silk cloth dipped in a little anhydrous alcohol (anhydrous alcohol must not come into contact with varnish). 5.1.4 Storage time of the balance
If the balance has been kept indoors, for balances of level D (I>, and above, as long as the knife has been moved, it should be parked for 48 hours before formal calibration; if the knife has not been moved, it should be parked for 2 hours to 3 hours before formal calibration; for other balances of level D (D, and below, as long as the knife has been moved, it should be parked for 24 hours; if the knife has not been moved, it can be formally calibrated after 1 hour to 2 hours. 5.2 Verification items
The verification items of the metrological performance of Daping are shown in Table 6: Table 6 Verification items
Verification items
Appearance inspection
Verification scale graduation value and its error of the balance The error of the unequal arm of the beam of the balance
First verification
Subsequent verification
In-use inspection
Verification items
Repeatability of the indication of the balance
JJG 98—2006
Table 6 (continued)
First calibration
Weighing error of vernier scale and chain scale
Combined error of mechanical support scale
Subsequent calibration
In-use inspection
Note: For single-pan balances, "3" item calibration is not valid; For balances without vernier scale or chain scale device, "5" item calibration is not required; For balances with mechanical weight addition or subtraction, "6" item calibration is not required. 5.3 Verification method
5.3.1 External inspection
Check the appearance quality of the balance by visual inspection and dynamic inspection to see if it meets the corresponding provisions of 4.1. 5.3.2 Calculation of balance balance position
When verifying the balance, the differential scale, ordinary scale or digital scale with damper shall take one reading as the balance balance position; the ordinary scale balance without damper shall calculate the balance balance position by three consecutive turning point readings. The formula for calculating the balance balance position by three turning point readings is +2i2 + i3
Where: , 22, 23——-are the first three readings of the four turning point readings respectively. (1)
5.3.3 Verification of all metrological performance of the balance requires the continuity of the entire verification process and shall not be stopped midway, otherwise it shall be re-verified. When there is doubt about the reliability of the verification result, the questionable items can be re-inspected. When doubts arise about the repeatability of the indication, the entire process must be rechecked. 5.3.4 Verification of the scale graduation value and its error, the beam unequal arm error and the indication repeatability of the large balance.
5.3.4.1 Verification of the scale graduation value and its error, the beam unequal arm error and the indication repeatability of the double-pan balance. 1) The verification procedure and steps for the verification scale graduation value and its error, the beam unequal arm error and the indication repeatability of the double-pan balance shall be carried out in accordance with Table 7:
Table 7 Verification procedures and steps for double-pan balance
Load on the pan
Pz(+)+r
Pi(+k)
Pr(+k)
Big balance reading
Balance position
When measuring the four corners, the
weight is placed at a distance of R/3
from the center of the scale pan, and R is the load on the scale pan
P(front)
Pr(back)
P(left)
Pr(right)
P(front)
P,(back)
P(left)
P(right)
P2 + r
P2(back)
P2(front)
P(right)
P2(left)
2(front)
P2(back)
P(left)
JIJG 98—2006
Table 7 (continued)
Balance reading
Balance position
When measuring the four corners, the weight is placed at a distance of R/3
from the center of the scale pan, and R is the scale pan
1 When the type evaluation of the balance is carried out, the verification of the (I)~CI2, level balance shall be carried out according to steps 1 to 25 in Table 7; the verification of the (I)~ID1, level balance shall be carried out according to steps 1 to 17 in Table 7. (Note 1 provides reference calibration steps for type evaluation). 2 When conducting the initial calibration, post-calibration, in-use inspection and random inspection of balance products in daily circulation, the following simplified calibration is allowed: The calibration of (I), (D), and (D) level balances shall be carried out according to steps 1 to 17 in Table 7; the calibration of (D, I, and (D) level balances shall be carried out according to steps 1 to 13 in Table 7; the calibration of (ID, I, and (ID) level balances shall be carried out according to steps 1 to 11 in Table 7. 3 When measuring the balance position of 1, 14, 1g, and I, the weights P and P corresponding to the maximum weight shall be placed near the center of the weighing pan. When measuring the balance position of I, I13Iis1, I, and Ias, the weights P and P2 corresponding to the maximum weight shall be placed 1/3 of the way from the center of the weighing pan as shown in the record sheet. At the corresponding position of the weighing pan radius. For 50kg and above, the scale may not be placed as shown in the record sheet. 4 The small base scale selected for measuring the graduation value of the balance calibration scale should be able to move the scale from zero to the end of the formal graduation for differential scale balances; for ordinary scale balances, the change in the equilibrium position should be no less than 3 graduations. The expanded uncertainty of this small base scale should not be greater than 1/3 of the nominal calibration scale graduation value of the balance being tested. For balances with unidirectional scales, the graduation value of the calibration scale can be measured on one arm.When the balance is upright, the weights P1 and P2 corresponding to the maximum weight should be placed near the center of the weighing pan. When measuring the balance position of I, I13Iis1, IIz1, I, and Ias, the weights P1 and P2 corresponding to the maximum weight should be placed at the corresponding position of 1/3 of the radius of the weighing pan that deviates from the center of the weighing pan as shown in the record table. For balances of 50kg and above, the weights may not be placed as shown in the record table. 4 The small weight selected for determining the graduation value of the calibration scale of the balance, for differential scale balances, should be able to move the scale from zero to the end of the formal graduation; for ordinary scale balances, the change in the balance position should be no less than 3 graduations. The expanded uncertainty of this small weight should not be greater than 1/3 of the nominal calibration scale graduation value of the balance being tested. For balances with unidirectional scales, the graduation value of the calibration scale can be determined on one arm.When the balance is upright, the weights P1 and P2 corresponding to the maximum weight should be placed near the center of the weighing pan. When measuring the balance position of I, I13Iis1, IIz1, I, and Ias, the weights P1 and P2 corresponding to the maximum weight should be placed at the corresponding position of 1/3 of the radius of the weighing pan that deviates from the center of the weighing pan as shown in the record table. For balances of 50kg and above, the weights may not be placed as shown in the record table. 4 The small weight selected for determining the graduation value of the calibration scale of the balance, for differential scale balances, should be able to move the scale from zero to the end of the formal graduation; for ordinary scale balances, the change in the balance position should be no less than 3 graduations. The expanded uncertainty of this small weight should not be greater than 1/3 of the nominal calibration scale graduation value of the balance being tested. For balances with unidirectional scales, the graduation value of the calibration scale can be determined on one arm.
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