A NOVEL GAS-FLOW METER

Aiming at high accuracy and ease of operation, a new gas flow meter was developed. A main feature of the instrument design is the use of a thin orifice with fixed conductance C for the generation of a known throughput q(pV). The throughput is easily obtained from the working pressure p by the relation q(pV) = p . C. In order to calibrate the conductance once, the instrument includes a constant pressure flow meter. The described instrument involves two orifices and two capacitance diaphragm gauges to cover a throughput range from 1.5 x 10(-5) to 1.5 mbar l s-1 for nitrogen; the uncertainty of the generated throughput amounts to about one per cent.