by Edward Morrell
High-speed clearance sealed piston provers for measuring gas flow rates have been available for over twenty years and have gained wide acceptance as a fast, cost-effective, primary calibration instrument for gas flow. High-speed piston provers are available for measuring flow rates from 0.5 sccm to 500,000 sccm with measurement uncertainties of up to 0.15%. This paper describes new advances in high-speed piston prover design.