National calibration / transfer standards

EPE calibration standards are transfer standards with the highest possible measurement uncertainty, the measurement results of which can be traced back directly to the SI units m and s. Over the past few years, we at EPE have designed a range of transfer standards that are designed for use in calibration laboratories.

As a technology partner of the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig, our solutions are based on the highest standard. One of the most important tasks of PTB is the realization and transfer of the legal units volume (m³) and flow rate (m³/h) or mass (kg) and mass flow (kg/h) of flowing gases, also in the area of application at high pressures. Various piston test benches and a gas measuring bell are available as standard. The EPE primary standards have been used successfully in various national, metrological institutes worldwide for years.

Calibration systems


  • Primary standards for national metrological institutes and calibration laboratories
  • Provision of national standard measuring devices
  • Calibration standard for critical nozzles, venturi nozzles, gas meters, differential pressure sensors, etc. in the atmospheric pressure range
  • Calibration of flowmeters for air and natural gas
  • Calibration of flowmeters for hydrogen (under development)


  • Lowest measurement uncertainty, ISO 9001 and DAkkS accredited

  • Traceable to SI units of length and time

  • Partner of the Physikalisch-Technische Bundesanstalt (PTB), member of the German Calibration Service (DKD)


BP – Bell ProverBPP – Bell Piston ProverDPF – Double Piston Flow ComparatorHPPP – High Pressure Piston Prover
Measurement sectionBells cylinder and standing vesselBell piston encapsulated in pipe sectionDouble pistons in cylindersPiston in pipe section
Measurement principleDisplacement of an enclosed air volume by sinking the bell cylinderDisplacement of an enclosed air volume by moving the bell piston using a stepper motorDisplacement of an enclosed air volume by moving the double piston using a stepper motorPassive, by a driven piston (driven by the gas flow) in a honed tube
Flow range0.1…300 m³/h2…16.000 l/h1.5 ml/h…120 l/h8…480 m³/h
Measurement uncertainties0.06…0.25 % MV0.08…0.3 % MV0.1…0.5 % MVup to 0,07 % MV
Pressure rangeAtmosphericAtmospheric up to partly 40 bar overpressureAtmospheric up to max. 6 bar overpressure15 to 100 bar overpressure
Medium AirAir, other gases (optional)Air, other gases (optional)Natural gas
Temperature range18…25 °C18…25 °C18…25 °C18…25 °C
Key BenefitLowest measurement uncertainty due to traceability to SI units length and timeLowest measurement uncertainty due to traceability to SI units length and timeLow flow measurement with the lowes measurement uncertaintyLowest measurement uncertainty with overpressure calibration of natural gas