What is NAWI?

Updated 25/06/2018

If you're a regular user of weighing scales, you may have come across the letters 'NAWI' in the past. To provide more background on how the weighing industry is regulated, and why Marsden's digital weighing scales are so accurate, this blog post provides an explanation of NAWI and Class III/trade approval.

NAWI is the directive behind what makes a scale Class III approved (or trade approved, as it's more commonly known in industry).



Class III is the approval which makes a scale legal for use within medical environments. For monitoring, diagnosis and treatment of patients the scale must be Class III approved.

Within industry, a scale must be Class III (or trade) approved if money is going to exchange hands and an invoice raised due to weight. We talk more about trade approval in retail and industry in this recent blog post.

A directive, 2009/29/EC, was introduced in April 2009 to help with harmonising the rules which apply to weighing instruments. This directive was specifically put in place to help protect the public against the consequences of incorrect weighing results. In medical environments this can ensure accurate results are given, for example to make sure correct doses of medication are administered in correlation to a person's weight.

The directive was succeeded by NAWI directive 2014/31/EU, which included a number of small changes to the regulation. A full list of changes made to the directive can be found here.

Under the NAWI regulation weighing instruments have to undergo conformity  assessments. These assessments can either be performed by the manufacturer or a recognised third party, such as trading standards. When the conformity assessment has been carried out a Declaration of Conformity will be produced to show that the scale is in line with the 2014/31/EU directive, showing that the scale is Class III approved.

Within the NAWI directive it states that weighing instruments have to undergo certain tests, both preliminary and metrological, to abide by the 2014/31/EU directive. For more information about the NAWI directive click here.

All scales that have been approved under the EC directive, and calibrated in accordance with precision Class III are clearly identified on our website at the bottom of the page with a Class III symbol. Every single Marsden scale that carried this badge meets the requirements of the Directive for Non-Automatic Weighing Instruments for medical (and industrial) use 2014/31/EU.

It's recommended that all weighing scales are serviced annually to ensure they are still compliant with the NAWI directive in order to maintain their class approval.

Very few UK companies can offer on-site re-verification - and Marsden are one of them. We offer nationwide coverage and currently handle over 200 NHS contracts. We are accredited to verify most makes of scale on-site.

Marsden are a true one-stop solution to purchasing and maintaining medical weighing equipment in accordance with Directive 2014/31/EU.

For more information about our service contracts or NAWI just get in touch with our service department by emailing service@marsdengroup.co.uk - or click here.

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