The gas facility of Euroloop is the world’s largest and most accurate calibration facility for high pressure and high flow gas meters. Due to the closed loop principle it is not subject to any seasonal influences. Natural gas is available from our gas storage with a total capacity of 7,000 m³.

Operating a closed loop facility provides the opportunity to calibrate flowmeters at freely selectable pressures anywhere between 9 and 61 bar(a). Our unique blower configuration can generate stable flows between 20 and 30.000 Am3/hr. A balanced multistep cooling system allows us to maintain temperature stability non-stop.


Euroloop exploits the master meter method based on the mass conservation principle. In order to relate volume quantities to mass, the GERG2004 equation of state is used to calculate the actual density and real gas factors. The calculation is based on the full gas composition retrieved from the process gas chromatograph. All quantities measured are corrected for known deviations, and the double timing method is used to avoid truncation of pulses in the time interval during which a calibration run is performed.
The system is equipped with eight mastermeters, ranging from 16 to 2 inch. Each mastermeter is accompanied by an ultrasonic flowmeter, providing us with essential information regarding our reference system.
Depending on the requested flow-range, a single or multiple parallel mastermeter(s) will be chosen as a reference.


The calibration results can be compared with performance criteria as stated in the European Measuring Instruments Directive (MID), OIML R137-1, 2, AGA-7, AGA-9, ISO 9951, ISO 17089-1, EN 12261 or customer specifications. If necessary, the meter will be adjusted and one or more verification runs will be performed to verify the correctness of the adjustment. Finally, the results are presented on the calibration certificate.


The values given on our certificates are directly traceable to the Dutch National Standards. The Gas Oil Piston Prover (GOPP) is the primary standard for the cubic meter of gas in the Netherlands, within the range of 1-61 bar absolute pressure. A transfer standard (TraSys) consisting of five dual head rotary meters, calibrated with GOPP at several pressures, together with different turbine reference meters create the link from the GOPP to the full operational range of Euroloop.


Euroloop has an ISO 17025 accreditation for calibration laboratories issued by the Dutch Council for Accreditation (RvA) pertaining to, flow rate and volume calibrations for the majority of its operating range. The actual scope of accreditation is published on under certificate number K161 . RvA accreditation is (internationally) accepted in over 80 countries through the International Laboratory Accreditation Cooperation (ILAC).