Test Masses come in a wide range of classes, sizes, materials and accuracies. The combination of specifications will determine which masses suit your purpose, whether or not they meet your quality assurance processes, and will also affect the price greatly.
This guide is intended to explain the various elements to enable informed purchasing decisions. Wedderburn metrology specialists are available to help you navigate your choices.
When choosing masses, you need to consider the following aspects.
Wedderburn specialists can advise you on the correct masses to purchase based on your specific requirements.
Just like scales it is important to have masses tested on a regular basis to ensure that the mass is stable and still fit for purpose.
Wedderburn generally recommend a calibration frequency of 12 months for general use mass pieces.
We have qualified technicans located throughout New Zealand to perform mass calibration tests and provide supporting traceable documentation.
Masses can be constructed using the various materials including; stainless steel, brass and cast iron. We’ve outlined benefits and potential downsides of each.
Stainless Steel is used for higher accuracy masses
Benefits; will not rust or corrode, not susceptible to magnetism, very stable
Downsides; expensive, generally not adjustable
Brass is used for medium accuracy test weights.
Benefits; rust resistant, not susceptible to magnetism, adjustable (generally in masses larger than 50g), relatively cost effective
Downsides; may tarnish and go green due to oxidisation which will change the value of the mass,
Cast Iron is used for larger masses and where lower accuracy is acceptable (legal).
Downsides; will rust, can be magnetised
Masses accuracy can be affected by the following;
It is important to know how to use your test masses correctly and how to interpret the results.
Here’s how to check your scale.
What do if the scale indicator is not the same as the mass?
If the problem still persists, please contact your local Wedderburn technical service team.
Metrology is defined as “the science of weights and measures or of measurement” and “a system of weights and measures”.
In New Zealand, the weighing industry is guided by recommendations made by OIML (International Organisation of Legal Metrology).
These recommendations include how scales function, the shape and size of masses and construction of Load cells among other things.
OIML Weight Classes and Mass Tolerances, as published by OIML (International Organisation of Legal Metrology), can be found in our publication "Wedderburn Guide to Mass Selection and Testing" on pages 3 and 4 respectively.
Download Wedderburn Guide to Mass Selection and Testing v2PDF 563KB