STABLE IONIZATION-TYPE ANEMOMETER HAVING AN OPTIMALLY ADJUSTABLE MEASUREMENT RANGE

A gas whose velocity is to be measured is passed through an ionization tube, and a first voltage proportional to the resulting ionization current is applied to one of two measurement arms of a bridge. A second voltage equal in magnitude to the first voltage when the velocity of the gas through the tube is zero is applied to a second arm of the bridge to set a zero reference on an ionization current meter connected between corresponding points on the measuring arms. The meter is then adjusted for full-scale deflection when the first voltage is reduced to zero to set the upper limit of the measuring range. The ionization current read on the meter during actual gas flow will now be accurately indicative of the flow velocity irrespective of the density and composition of the gas.