Performance of Coriolis meters in transient gas flows

• NIST built a Transient Flow Facility (TFF) that mimics cascade type gaseous refueling.
• The TFF operates using helium gas at pressures up to 42 MPa.
• The TFF uses a critical flow venturi as its reference standard.
• The TFF was used to test two Coriolis meters.
• The Coriolis meters were capable of measuring the totalized mass within 1.0%.

For steady flows, Coriolis flow meters accurately measure mass flow. To study the performance of Coriolis meters under transient flows, we measured the instantaneous and totalized flow determined by two Coriolis meters. The tests used a Transient Flow Facility (TFF) developed to generate transient flow, pressure, and temperature conditions similar to those that occur when a hydrogen powered vehicle is refueled. During simulated cascade fills, the TFF discharged 3 kg of helium in 3 min at flows between 10 g/s and 45 g/s through the Coriolis meters and the TFF׳s standard. The TFF׳s expanded uncertainty (95% confidence level) for totalized mass during this cascade fill was 0.45%. For the same simulated cascade fill, both Coriolis meters measured the instantaneous flow within the uncertainty of the TFF and measured totalized flow within the International Organization of Legal Metrology Recommendation 139 maximum permissible errors for meters in gaseous fuel dispensers (1.0%).