Medical Scales, Medically Approved, Class III, Green M - What does it all mean?

Lots of different terms are used for medical scales which can be used in a medical environment - medically approved, class III and Green M are just a few - but what exactly do they all mean and do they actually matter if you're buying scales for medical use?

In this article I'll try and explain what means what, and hopefully simplify the purchasing process.

The Non-Automatic Weighing Instruments (NAWI, there's another one!) directive was made part of UK law in January 1993 and aims to not only control the technical and performance characteristics of weighing instruments, but also to specify which tasks require approved weighing equipment.

What is worth knowing at this point is that any weighing equipment being used in health clubs, fitness centres and slimming clubs for instance, do not have to conform to NAWI regulations.

In addition to the NAWI regulations, only scales which use metric units are legal for controlled purposes. Scales that use both metric and imperial can still be used, but only the metric units are strictly legal for medically approved measurement.

So, getting back to the many terms for medically approved...

Class

The NAWI regulations define 4 different levels of accuracy known as 'Classes'. Classes I and II are for very high accuracy instruments and are not often seen in everyday medical products. Class III is for weighing scales in general use for trade (in our case, medical scales), and Class IIII where a lower level of accuracy is acceptable. The maximum permissible error of a scale is related to its Class.

The UK Weighing Federation believes that Class IIII scales are only suitable for checking a patient's weight for record purposes such as in a doctor's consulting room. When weighing for diagnostic or treatment purposes, such as in hospital, a Class III scale should be used. Various scales are available for this purpose including medically approved column scales, floor scales and chair / wheelchair scales.

CE and Green M

All weighing scales that conform to NAWI must have the Green M and CE mark. Weighing scales that do not conform to NAWI may have the CE mark to show they conform to other EC directives, but cannot legally be used for medical purposes unless they have the Green M label.

If you have any other questions about medically approved scales feel free to contact us.