TS–006 When is a full verification test required for weighing and measuring instruments

Reference documents

• Weights and Measures Act 1987(external link)
• Weights and Measures Regulations 1999(external link)

Policy

Where the mark of verification (MOV) or sealing has been broken, for the purposes of accessing an instrument's calibration settings or to alter any metrological characteristic, the instrument must be verified by performing a full verification test.

This also includes, but is not limited to, replacing any of the following components that can affect the metrological characteristics of the instrument:

• Load cells,
• Junction boxes,
• Indicator or indicating device,
• PEC board in an indicator, 
• Flow meters, or
• Any calibration action that causes an instrument's event-counter to increment.

Furthermore, this includes, but is not limited to, altering any of the following calibration functions:

• Span adjustment,
• Zero adjustment, or
• Meter alteration or a K factor adjustment.

Exemption:

There can be instances where an instrument has the MOV removed or sealing broken to gain access to the instrument's interface and upgrade the non-legally relevant software or replace hardwired auxiliary devices e.g., a printer or secondary indicator, that has no effect on the metrological characteristics of an instrument.

This activity is permitted if:

• The instrument has a current certificate of accuracy,
• The MOV or sealing is removed, and subsequently replaced, by the accredited individual who applied the certificate of accuracy,
• Any existing certificate of accuracy is not altered or removed, and
• The test sheet that was completed when the certificate of accuracy was issued is updated with the date and details of the action completed.

Any other instance requires the prior written approval from Trading Standards or a full verification test is to be performed.