Precision and commercial weights

Adjustment weights and test weights are used for checking and adjusting / calibrating electronic scales (e.g. industrial scales, hanging scales, precision scales, etc.) such as in routine tests. The BOSCHE company offers the right test weight/weight set for every scale and application. Various materials such as cast iron, stainless steel or brass as well as shapes such as block weights, fine weights or a plate shape are available. Optionally, you can also receive the matching case for your individual weights and weight sets. Read more...

The appropriate test weight

Correctly selected calibration weights or test weights are a prerequisite for the adjustment/calibration of scales. Regular checking of the scales with test weights helps to ensure quality standards and maintain QM goals. A scale can never be more precise than the adjustment weight used to adjust it, because the tolerances are what matter.

Example:

Weighing range Max 2000 g = 2 kg
Readability d = 0.01 g = 10 mg
The test weight is usually identical to the weighing range: test weight has the weight size. ße 2 kg.
The accuracy of the test weight results from the readability d with approx. +10 mg.
The appropriate test weight with tolerance +10 mg and weight size e 2 kg can be found in class F1.

How are the required nominal values (weight sizes) determined?

The minimum test

It is possible to carry out almost all metrological tests for the weighing range with just ONE test weight (nominal value). The nominal value of the external adjustment weight is usually used for this (see your operating instructions or the operating software supplied with your scale). Please note that the nominal value is always higher than 80% of the maximum load.

The complete exam

If you want to check the weighing range (measuring range) of your scale for requirements in the maximum range, this procedure is ideal. To do this, you need test loads with 25%, 50%, 75% and 100% (or at least 80%) of the maximum maximum load.

The highest test load of 100% or at least 80% should not be a combination of different weights, but rather consist of ONE weight.

When handling test weights in connection with the highly sensitive technical area of weighing, the highest level of accuracy is understandably important. In order to adequately take into account the need for the most general standard possible in this delicate area, the “Organization Internationale de Metrologie Legale” (OIML) developed and published a guideline R111-2004, which is used in around 100 countries.

According to this guideline, the following 7 accuracy classes are defined:

E1: Testing and calibration weights for calibration and quality assurance of scales with a step number > 1 000 000
Material: stainless steel, magnetic polarization, μ0M < 2.5 µT, milligram weights in wire form. A DAkkS calibration certificate should always be used in connection with the test weights.
During the initial testing of E1 weights, a volume determination is made.

E2: Testing and calibration weights for calibration of fine scales (Class I) with a number of steps < 1 000 000
Material: stainless steel, magnetic polarization, μ0M < 8 µT, milligram weights in wire form.
The accuracy class E2 with the corresponding weights is intended for high-resolution analytical balances that meet calibration class I ≥ 100,000 e belong.

F1: Adjustment, testing, calibration instrument for commercial scales (Class II) with a number of steps < 300 000
Material: stainless steel, highest magnetic polarization, μ0M < 25 µT, milligram weights in platelet form.
The accuracy class F1 with the associated test weights applies to analytical balances and precision balances of calibration classes I/II ≤ 100,000 e.

F2: Adjustment, testing, calibration instrument for commercial scales (Class II) with a number of steps < 100 000
Material: stainless steel, magnetic polarization, μ0M < 80 µT, milligram weights in platelet form.
With the test weights of accuracy class F2, precision balances of calibration class II ≤ 30,000 e tested.

M1: Calibration weights as a calibration instrument for commercial scales (Class III) with a step number < 30 000
Material: stainless steel, magnetic polarization, μ0M < 250 µT, cast iron block weights.
With the test weights of accuracy class M1, industrial and commercial scales of calibration class III ≤ 10,000 e to check.

M2: Test weights for testing commercial scales (Class III) with a number of steps < 10,000
Material: Finely turned brass, button shape, cast iron block weights. Commercial scales of classes III and IV with a resolution of n = 5,000 d can be checked with the test weights of accuracy class M2.

M3: Trade weights as a testing instrument for trade scales (Class III) with a step number < 3,000
Material: Finely turned brass, button shape, cast iron block weights.
Mechanical panel scales and decimal scales are checked with test weights of accuracy class M3.

Explanation of the classes

It is easy to see that tolerance class E1 applies to precision weights, which are the most accurate, because it has the smallest tolerance range. In the following tolerance classes, this tolerance range gradually increases up to the tolerance class M3 in the last column with the largest tolerance range.

The specified nominal values are of particular importance. These nominal values indicate the smallest and the largest permissible weight according to the class of this established standard R 111. Outside these ranges, the tolerance values may not be extrapolated.

Example:
The smallest weight of class M 3 is 1 g, while the largest weight of the same class is 5000 kg.

Error limits for weights - Error limit classes:

The error limit of a weight corresponds to the permissible tolerance, i.e. the largest permissible tolerance. liquid deviation from the nominal value according to plus and minus. The error limit classes for weights are strictly hierarchically graded and defined in the OIML. The following table contains the OIML guideline R111-2004:

Nominal value Error limit classes for weights according to OIML (tolerances ± )
  Mass standards and normal weights Fine weights Precision weights and commercial weights
  E1 E2 F1 F2 M1 M2 M3
1 mg ± 0.003 mg ± 0.006mg ± 0.020mg ± 0.06mg ± 0.20mg    
2 mg ± 0.003 mg ± 0.006mg ± 0.020mg ± 0.06mg ± 0.20mg    
5 mg ± 0.003 mg ± 0.006mg ± 0.020mg ± 0.06mg ± 0.20mg    
10 mg ± 0.003 mg ± 0.008mg ± 0.025mg ± 0.08mg ± 0.25mg    
20 mg ± 0.003 mg ± 0.010mg ± 0.03mg ± 0.10mg ± 0.3mg    
50 mg ± 0.004 mg ± 0.012mg ± 0.04mg ± 0.12mg ± 0.4mg    
100 mg ± 0.005 mg ± 0.016mg ± 0.05mg ± 0.16mg ± 0.5mg ± 1.6mg  
200 mg ± 0.006 mg ± 0.020mg ± 0.06mg ± 0.20mg ± 0.6mg ± 2.0mg  
500 mg ± 0.008 mg ± 0.025mg ± 0.08mg ± 0.25mg ± 0.8mg ± 2.5mg  
1 g ± 0.010 mg ± 0.03mg ± 0.10mg ± 0.3mg ± 1.0mg ± 3.0mg ± 10mg
2 g ± 0.012 mg ± 0.04mg ± 0.12mg ± 0.4mg ± 1.2mg ± 4.0mg ± 12mg
5 g ± 0.016 mg ± 0.05mg ± 0.16mg ± 0.5mg ± 1.6mg ± 5.0mg ± 16mg
10 g ± 0.020 mg ± 0.06 mg ± 0.20mg ± 0.6mg ± 2.0mg ± 6.0mg ± 20 mg
20 g ± 0.025 mg ± 0.08mg ± 0.25mg ± 0.8mg ± 2.5mg ± 8.0mg ± 25mg
50 g ± 0.03 mg ± 0.10mg ± 0.3mg ± 1.0mg ± 3.0mg ± 10mg ± 30mg
100 g ± 0.05 mg ± 0.16mg ± 0.5mg ± 1.6mg ± 5.0mg ± 16mg ± 50mg
200 g ± 0.10 mg ± 0.3mg ± 1.0mg ± 3.0mg ± 10mg ± 30mg ± 100mg
500 g ± 0.25 mg ± 0.8mg ± 2.5mg ± 8.0mg ± 25mg ± 80mg ± 250mg
1kg ± 0.5 mg ± 1.6mg ± 5.0mg ± 16mg ± 50mg ± 160mg ± 500mg
2 kg ± 1.0 mg ± 3.0mg ± 10mg ± 30mg ± 100mg ± 300mg ± 1000mg
5kg ± 2.5 mg ± 8.0mg ± 25mg ± 80mg ± 250mg ± 800mg ± 2500mg
10 kg ± 5.0 mg ± 16mg ± 50mg ± 160mg ± 500mg ± 1600mg ± 5000mg
20 kg ± 10 mg ± 30mg ± 100mg ± 300mg ± 1000mg ± 3000mg ± 10g
50 kg ± 25 mg ± 80mg ± 250mg ± 800mg ± 2500mg ± 8000mg ± 25g
100 kg   ± 160mg ± 500mg ± 1600mg ± 5000mg ± 16g ± 50g
200 kg   ± 300mg ± 1000mg ± 3000mg ± 10g ± 30g ± 100g
500 kg   ± 800mg ± 2500mg ± 8000mg ± 25g ± 80g ± 250g
1000 kg   ± 1600mg ± 5000mg ± 16g ± 50g ± 160g ± 500g
2000 kg     ± 10g ± 30g ± 100g ± 300g ± 1000g
5000 kg     ± 25g ± 80g ± 250g ± 800g ± 2500g

 

Calibration of test weights (re-calibration)

Test weights may only be carried out by special testing laboratories that have been accredited for this purpose by the Dakks (German Accreditation Body). , need to be recalibrated.
As part of the recalibration of test weights according to DAkkS specifications, calibration certificates are issued for documentation purposes.

Calibration validity period of weights

Weights of error limit class E2 4 years
Weights of Error limit class F1, F2 4 years
Weights of the error limit class M1-M3 4 years
Control weights, all classes 1 year 

Since the test weight for the scale only becomes an ISO 9000ff -compliant test instrument once its accuracy has been proven, we also offer you a suitable DKD calibration certificate for the test weights.
The DKD calibration certificate serves as proof of the correctness of the weight and offers the best prerequisite for correct scale calibration.

Experiences and references of test weights

If you need powerful scales with which you can maintain the highest levels of accuracy, it is best to turn to a professional manufacturer of such scales. Bosche GmbH & Co. KG is one such manufacturer that not only guarantees and maintains the highest quality for its products, but can also point to numerous references from well-known companies.

In the specialized area of weighing technology, Bosche is the first choice with an extensive product range, which includes, among others, the following types of scales: industrial scales, logistics scales, mobile scales, agricultural scales, medical scales, crane scales, special scales, scale accessories

Conclusion

In numerous areas of technology and business, such as medical and laboratory technology, it is necessary to be able to weigh items and products with the highest level of accuracy. This requires precision scales that meet all the necessary requirements and requirements associated with modern weighing technology. The Bosche company not only has all the certifications to be able to work successfully in this extensive specialist area, but also has an experienced staff that is available to provide advice and support to anyone interested in scales of any kind at any time.