Ok, so you need to buy a medical scale...what type of scale should you buy? How do you make sure you can legally use it? What does Class III Approved mean? And what are M stickers and CE marks anyway? ...Confused? Hopefully not by the end of this guide...

The importance of accurate medical weighing cannot be underestimated. Stories in the press over the past few years have highlighted cases of people becoming ill after their prescriptions were calculated from non-approved and inaccurate scales, even though, by law, all scales used for professional medical use must be Class III approved.

Where non-Class III scales are being used it is often due to misinformed purchasing departments or doctors being simply unaware that the scales they are using are not suitable for their needs. It is vitally important that consumers are aware of the legal requirements that are in place to ensure medical weighing is regulated and accurate. This guide will aim to explain these regulations and highlight your obligations as a medical scale purchaser.

One of the key documents in the regulation of medical scales is the Non-Automatic Weighing Instruments Directive (or NAWI for short). This important document defines the legal requirements for weighing scales that are to be used in the EU. Since January 1st 2003*, the NAWI Directive has applied to all scales used for the following purpose**:

(From this definition, scales used in, for example, slimming classes or fitness centres do not have to conform to the NAWI regulations - as long as the weighing is only for reference and is not used for any purpose mentioned above.)

*Scales purchased before this time are not affected - but may be subject to the requirements of other regulations.

**There are 5 other purposes too, but for this guide we will focus only on medical scales.

Now we have determined how the NAWI Directive applies to medical scales, we need to look at what the NAWI Directive says we need to do as consumers. In short, you need to ask your medical scale supplier to confirm that the scale you are purchasing meets the requirements of the NAWI Directive Regulations and check that the scale bears the necessary symbols, which are:

- a CE Mark (the manufacturer's declaration that their product meets the requirements of the applicable EC laws)

- an M sticker (the manufacturer's declaration that the scale conforms to NAWI)

- a 4 digit number (the identification number of one of several bodies who are authorised to test instruments and confirm that they accord with the European Directive on which the regulations are based).

The NAWI directive defines the level of accuracy required by a weighing scale by giving it a Class. The most accurate being Class I which is used for highly accurate weighing where very little error in the result is accepted. The accuracy requirements of Class I and Class II scales are too great for most applications, so the most common accuracy class and the one that is used for trading (selling by weight - like in your local grocery) and medical weighing is Class III.

Before it can be used as an approved weighing instrument, a scale must undergo a strict procedure known as a "Verification Test" (sometimes called a "Stamping"). A Verification Test puts a scale through numerous demanding procedures where it must perform to the required accuracy of its Class.

Among other procedures, the Verification Test includes "Weighing Performance" (where certified weights are placed on the scale all the way from zero to the scale's capacity - the maximum weight the scale can legally show) and "Repeatability" (where the same weight is placed on and off the scale multiple times). During these tests, in order to pass, the scale is only allowed to have errors or inaccuracies that fall within the maximum allowed errors for it's Class.

The Verification Test can only be undertaken by Approved Verifiers who have the authority to "stamp" a scale (or verify that it can be use as an approved scale). Once the scale has passed its test, the verifier marks the scale by a) placing a sticker on it with their 4 digit code, M and full postal details b) sealing it so it cannot be tampered with and c) issuing the Declaration of Conformity which is the certificate that comes with a Class III Approved scale to show it meets all required regulations.

Now that the legal side has been explained, you just need to decide which scale best suits your needs. There are many different types of scale, ones where you can stand on them and see your weight (some of these also have height measures and can show you your BMI or Body Mass Index - an indication of your height to weight ratio), ones where you can sit on them, and ones that can be used with wheelchairs.

 

Once you have decided which type of scale you need, the next step is to decide how big you will need it to be and the maximum weight you will need to put on the scale (this is known as the capacity of the scale).

 

Most of our scales come in standard sizes and standard capacities which will cover most applications, but if you need a larger scale or a higher capacity it may be worth looking at the Bariatric range. We specialise in Bariatric weighing and offer a wide range of high capacity models to suit all requirements. Please click here to see our range of Medical Scales.