A direct reading ionic discharge flowmeter capable of measuring rates
of flow of gases from 0.30 mu g s(-1) to 0.20 mg s(-1) is described. T
he meter uses a differential current and voltage measurement arrangeme
nt. The meter functions best at a pressure of 4 x 10(2) Pa and has app
lication for use with dry non-explosive gases. A semi-empirical model
is devised to explain the theory of the instrument.