In-service verification must usually be performed regularly on measuring instruments

The company or other party using the measurement result is responsible for ensuring that the measuring instrument operates reliably throughout its service, and that the verification of the measuring instrument is valid. 

Regular in-service verification of measuring instruments is usually required.  The verification checks that

  • the measuring instrument and system operate reliably
  • no unauthorised changes have been made
  • the structure of the measuring instrument and system conform to the approval
  • the measurement error does not exceed the maximum permitted error limits.

The measuring instrument must also be verified whenever there is a reason to suspect its reliability or when its markings or seals are damaged.

The table shows examples of the requirements of different measuring instruments and the verification intervals.

An in-service verification must be performed on the measuring instrument every 3 years. Exceptions:

  • 2-year verification interval
    • liquid fuel measuring systems: liquid fuel and gas used as fuel in vehicles
    • automatic line scales used to check the quantity contained in the package
  • no in-service verification
    • material measures and measures at open-air marketplaces, if the measure and its markings are not broken
  • no detailed regulations available yet
    • Consumption meters

Verification procedures for various measuring instruments
before and after commissioning

Requirements on
 measuring instruments

 Before commissioning After commissioning

Type examination and verification (national or EC)

 In accordance with MID or NAWID
Measuring instrument Type examination Initial verification Declaration of conformity

In-service verification

Verification interval
(years)

 
Ordinary shop scales (NAWI)     x x 3
Automatic scales     x x 2/3²
Weight (>50 mg)

 

 x _¹ x 3
Liquid fuel distribution meter     x x 2
Compressed natural gas (CNG) or compressed biogas (CBG) measuring system for vehicles x x _¹ x 2
Liquefied natural gas (LNG) measuring system     x x 3
Liquefied natural gas (LNG) measuring system for vehicles     x x 2
Lubricating oil meter     x x 3
Road tanker meter (liquid fuel)     x x 2
Milk tanker meter     x x 3
Transport container x x _¹ _  
Measure of length     x _  
Height meter     x x 3
Capacity serving measure (≤5 l)     x _ _
Wooden potato measures and cylinder measures used at open-air marketplaces   x   _ _
Optic (non-drip) measure _ x _¹ x 3
Meter for beer/cider x x _¹ x 3

Consumption meters
Thermal energy meter
Water meter
Electrical energy meter
Gas meter

     x upcoming  

¹ These measuring instruments are not covered by MID, and national type approval and verification requirements still apply.


² Line scales used to check the quantity contained in the package are verified every 2 years, while other automatic scales are verified every 3 years.

MID = Measuring Instruments Directive
NAWID = Non-Automatic Weighing Instruments Directive