New high-pressure calibration facility for gas meters
Closed Loop Pigsar provides longer test sections and larger pressure and flow rate ranges
The national standard for high-pressure gas of the Federal Republic of Germany has been operated at Pigsar in Dorsten for more than 20 years. A piston prover of PTB is an integral part of the Pigsar system. The Pigsar bypass test rig is currently the most accurate high-pressure facility in the world. Bypass means that for testing and calibrating gas meters, gas is tapped from a transport pipeline under high-pressure conditions and is fed back downstream at lower pressure conditions. Due to new customer requirements and increasing fluctuations in the gas transmission system, it has become necessary to enhance testing capabilities and to make them independent of the grid. A new measuring system has therefore been created to allow tests to be performed within a closed gas circuit, called “closed loop”. The facility also provides longer test sections and larger pressure and flow rate ranges. With the blowers at a power of 2.5 MW, natural gas takes less than 10 s to circulate. The bypass test rig for smaller and medium-sized meters and devices with high pressure loss is still in parallel operation.
Prior to the new system’s construction, a PTB case study confirmed that the accuracy aimed for could be reached. In Braunschweig, PTB performed additional tests with air to determine the parameters necessary for characterizing the meter curve. This curve is used to correct the test standards on site at Closed Loop Pigsar.
The Closed Loop’s measurement capabilities have been recorded in the DAkkS accreditation and are included in the recognition of Pigsar as a state-approved test center. The facility will take part in the next interlaboratory comparison for the harmonized cubic meter. Furthermore, PTB continues to work on reducing the measurement uncertainties of the high-pressure gas flow traceability. In addition, investigations have been conducted on how to scale gasmeter calibrations at Closed Loop Pigsar to applications with renewable gases such as hydrogen.
Contact
Jos van der Grinten
Department 1.4, Gas Flow
Phone: +49 531 592-1425
jos.v.grinten(at)ptb.de
Scientific publication
Jos van der Grinten, Detlef Vieth and Bodo Mickan (2018): The new Closed Loop pigsar high-pressure gas flow calibration facility and its projected CMC, 36th International North Sea Flow Measurement Workshop, Aberdeen, 22 – 24 October 2018.