This standard applies to: 1.1 Rotary piston gas meters in which internal walls defining the measuring chambers are set in rotary and the number of revolutions of these walls represents a measurement of the volume of the gas passed. 1.2 Turbine gas meters where the glass flow rotates a turbine wheel and the number of revolutions of this wheel represents the volume of the gas passed. With regard to the gas meters defined above, this standard complements GSO Standard to be approved by the organization on “General Provisions for Gas Volume Meters”, the provisions of which apply jointly with the requirements of this standard.