This document specifies requirements and tests for the construction, performance and safety of class 1,5 Capillary Thermal-Mass Flow sensor gas meters (hereinafter referred to as meter(s)). This applies to meters having co-axial single pipe, or two pipe connections, that are used to measure volumes of fuel gases of the 2nd and/or 3rd family, as given in EN 437:2018.
In general, the term "thermal mass flow meters" applies to a flow-measuring device using heat transfer to measure and indicate gas flowrate, as defined in ISO 14511.
NOTE 1 Although the word "mass" is present in the definition of the measurement principle, gas meters covered by this document provide measurement of gas at base conditions of temperature and pressure.
These meters have a maximum working pressures not exceeding 0,5 bar and a maximum flowrate not exceeding 160 m3⋅h−1 over a minimum ambient temperature range of −10 °C to +40 °C and a gas temperature range as specified by the manufacturer with a minimum range of 40 K.
This document applies to meters indicating volume at base conditions, which are installed in locations with vibration and shocks of low significance. It applies to meters in:
- closed locations (indoor or outdoor with protection, as specified by the manufacturer) with condensing humidity or with non-condensing humidity;
or, if specified by the manufacturer:
- open locations (outdoor without any covering) both with condensing humidity or with non-condensing humidity;
and in locations with electromagnetic disturbances likely to be found in residential, commercial and light industrial use.
For meters which indicate unconverted volume reference can be made to Annex C.
Unless otherwise stated, all pressures given in this document are gauge pressures.
Requirements for electronic indexes, valves and additional requirements for batteries incorporated in the meter and any other additional functionalities are given in EN 16314:2013.
Unless otherwise stated in a particular test, the tests are carried out on meters that include additional functionality devices intended by the manufacturer.
Clauses 1 to 13 are for design and type testing only.