Design and development of primary orifice plate flowmeter

Accurate and stable gas flows are very important in different applications like, the performance study of vacuum pumps, gauge calibration, leak detection and advance research in low pressure physics. Primary Orifice Plate Flowmeter (OPF) has been designed and developed indigenously. This flowmeter consists of two orifice plates. Orifice-1 (O1) acts as a flow restriction, while orifice-2 (O2) enables continuous pumping mode. By varying upstream pressure P1, a change in downstream pressure P2 is recorded, and the flow-rate is calculated from the conductance 'C' of the orifice O1 and pressure difference by the relation Q = C(P1 − P2). Main feature of this primary OPF is that it is very simple and compact. A stable and reproducible flow-rate has been achieved in the range of 10−5 to 10−6 mbar.l/s. A variation in Q has been observed with a change in temperature of orifice and orifice diameter.