Information on the accreditation categories: mass, length, volume, weighing instruments and measuring instruments.


Type Category Sub-category
Mass Traders weights M1 M2 M3  


Length Material measures of length  


Type Category Sub-category
Volume Measures of volume Milk and cream bottles
Oil bottles
Milk delivery measures
Milk delivery measures
(level test and/or volume test)
Beer delivery measures
Spirit dispensers
Cubic measures
Volume measuring instruments  

Weighing instruments

Type Category Sub-category
Weighing Instruments
(Includes both electronic and mechanical instruments)**
Miscellaneous weighing instruments  
Class I Precision balances
Class II Precision balances, beam scales, counter scales***

Class III and/or IIII

(no maximum capacity or state specific maximum capacity)

Maximum capacity ≤ 300 kg
Platform scales
Hoppers and bins
On-board weighing instruments*
Container weighing instruments*
Semi automatic weighers  
In-motion weighing Static mode
Dynamic mode
Belt weighers Class 0.5
Class 1
Class 2
Automatic catch weighing instruments Class Y(a) and/or Class Y(b) Package weighers
Vehicle mounted instrument
Container weighing instruments*
Automatic weighing instruments class X  

Measuring instruments

Type Category Sub-category
Measuring Instruments Class 0.3 Liquid measuring systems on pipelines
Class 0.5 Liquid measuring systems for refuelling aircraft or loading ships
Measuring systems for milk
Measuring systems for unloading ships tanks, rail tankers, or road tankers
Measuring systems for liquids of low viscosity on road tankers (also known as liquid fuel measuring instruments fitted on delivery vehicles)
Measuring systems in fuel dispensers (other than LPG dispensers) for motor vehicles (also known as fixed liquid fuel measuring instruments)
Measuring systems on overhead gantries
Other liquid measuring systems
Class 1.0 Measuring instruments dispensing liquefied gases under pressure measured at a temperature equal to or above -10°C that are:
- LPG dispensers for motor vehicles; or
- Measuring systems fitted on delivery vehicles; or
- Measuring systems on overhead gantries.
Measuring systems that are Class 0.3 or Class 0.5, but used for liquids that are of a:
- Temperature less than −10°C or greater than 50°C; or
- Dynamic viscosity higher than 1 000 millipascal second; or
- Maximum volumetric flow rate of 20 L per hour or less.
Class 1.5 Measuring systems for liquefied carbon dioxide, or liquefied gases under pressure (other than LPG) measured at a temperature below -10°C (other than cryogenic liquids)
Class 2.5 Measuring systems for liquids at a temperature below -153°C
Area measuring instruments  
Length measuring instruments  
Leather measuring instruments  
Multidimensional measuring instruments  
Direct mass flow measuring instruments  
Miscellaneous measuring instruments  

* See definition in glossary of terms.
** All test procedures must be documented and approved by Trading Standards.
*** Where a mechanical instrument incorporates traders weights, that is ‘weights that are part of the weighing instrument and are used to indicate a whole or partial weighing range’ the verifying Accredited Person must also hold accreditation for the category ‘Traders weights'.