A professional manufacture and sales of various electronic balances, moisture analyzers, viscometers and laboratory instrument manufacturer of weight measure instruments..
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A professional manufacture and sales of various electronic balances, moisture analyzers, viscometers and laboratory instrument manufacturer of weight measure instruments..
You are well aware of the importance of test weights in settings where accurate measurement is the priority. Test weights help you maintain the accuracy of your measuring instruments by calibrating and adjusting these devices and instruments regularly. Test weights are classified under international standards into different categories based on their application and suitability. Therefore, it is crucial to know and choose the exact appropriate test weights according to your application.
Two of the widely known and accepted classifications of test weights are those established by“International Organization of Legal Metrology (OIML)”and the“American Society for Testing and Materials (ASTM)”In this article, we will fully understand the basis of classification of both standards, the difference between both classifications, and most importantly, the application of specific classes of test weights.
What Are Test Weight Classes?
Test weights classes are different categories of test weights based on the level of precision, tolerance, and specific application. Based on the industry standards and the purpose of use, different instruments require different levels of precision and accuracy. The classification system guides the users to select appropriate class of test weights based on the specific requirements. For intense, highly precise instruments are required in a laboratory setting, while less precision needed for the large industry setting.
The classification system is governed mainly by two international regulatory bodies that are: International Organization of Legal Metrology (OIML) and the“American Society for Testing and Materials (ASTM)”. The ultimate goal of both the classification systems is to ensure the accuracy. However, they differ in terms of terminology, structure, and application.
OIML Test Weight Classes:
The International Organization of Legal Metrology (OIML) is a global governing body that establishes international standards for test weights and other measuring instruments. Based on the accuracy and specialized use, OIML divides the test weights into various classEs. These classes are:
E Class (E1 & E2)
● E stands for“Extra fine”. These weights are used for the calibration of ultra-high precision devices.
● These weights are usually made up of non-magnetic material such as stainless steel, to minimize environmental interference.
● E class is further divided into E1 and E2.
● E1 weights are the most accurate class of test weights due to extremely high tolerance. E1 weights are usually used in microbalances and analytical balances.
● E2 has a slightly less precision than E1, however, they are still the high precision test weights and often used in metrology labs.
F Class (F1 & F2)
● F stands for“Fine”. These weights are used for the calibration of high-precision devices in commercial and industrial settings.
● These weights are slightly less precise and less tolerant than E class.
● These weights are more often made up of stainless steel.
● F Class is further divided into F1 and F2.
● F1 weights are used in manufacturing, food production, and quality control labs.
● F2 weights are ideal for production lines and manufacturing plants.
M Class ( M1, M2, & M3):
● M stands for“Medium”. These weights have less precision than F class.
● These weights have moderate tolerance to balance accuracy as well as durability.
● M Class weights are often made from cast iron or stainless steel.
● M Class is further divided into M1, M2, and M3.
● These weights are used for the calibration of larger industrial scales, such as those in heavy manufacturing, trade, and agriculture.
OIML classification is a global standard for the accuracy of test weights. This system is widely adopted in Europe, Asia , and other regions.
ASTM Test Weight Classes
The American Society of Testing and Materials (ASTM) is a US based regulatory body for a wide range of measuring materials including Test Weights. Based on precision and accuracy, ASTM categorizes the test weights into the following classes:
Class 0:
● This is the highest precision class of ASTM system, comparable to OIML E1 Class.
● These weights are used for the calibration of high precision lab instruments, such as those in metrology labs.
Class 1:
● This class has a slightly less precision and accuracy than Class 0.
● These weights are used for calibration of analytical balances in laboratories.
● Most often used in pharmaceutical and research settings.
Class 2:
● These weights are slightly less precise than Class 2, but still highly accurate.
● Used for the calibration of good accuracy laboratory, industrial, and commercial scales.
Class 3:
● These weights are slightly less precise and have less tolerance than Class 2.
● Used for the calibration of general purpose, commercial and industrial scales.
Class 4:
● These weights have moderate precision and tolerance.
● Commonly used for the calibration of less critical industrial scales.
Class 5:
● This class is comparable with OIML M1 Class. These weights have less precision and moderate tolerance.
● Commonly used for the calibration of large industrial scales.
Class 6:
● This class has the least precision with the widest tolerance.
● These weights are useful for calibrating less precise, larger, and rough industrial scales.
● Commonly used in agriculture and construction applications.
The ASTM classification system is widely adopted in the united states for its detailed classes and specifications.
Difference Between Both Standards:
Both OIML and ASTM standards ensure the precision, accuracy, and the reliability of test weights. However, there are some key differences:
● Terminology: OIML system uses letters for representation of the classes (E, F, M), while ASTM uses numbers (0,1,2,3…).
● Regional Adoption: OIML classification is more widely accepted over the globe, while, the ASTM is primarily followed in the United States.
● Material: Both standards use high quality material such as stainless steel and cast iron, however, OIML uses more refined non magnetic material to enhance the accuracy.
Conclusion:
It is essential to understand the different classes of OIML and ASTM standards and the difference between them, because it helps you to select the appropriate test weight according to your required precision and the specific application. You can maintain the highest levels of precision and accuracy in the calibration process by selecting a suitable class of test weights.
However, it is also crucial to select and approach a trusted supplier like W&J Instruments. W&J Instruments provide high quality weights of all classes of OIML and ASTM standards. Whether you are working in a high precision setting like laboratories or a low precision industrial setting, you can find appropriate test weights for your use with W&J Instruments.
We also provide customized electronic balances/ laboratory scales with special functions according to customer needs.
