TEMPERATURE MEASURING INSTRUMENT FOR PRESSURE TYPE FLOW CONTROLLER

摘要

PROBLEM TO BE SOLVED: To actualize a pressure type flow controller for controlling the rate of an orifice passing flow with high accuracy by simultaneously measuring a fluid pressure and a fluid temperature at a same point in the fluid.;SOLUTION: This pressure type flow controller controls the rate of flow passing an orifice by computing Qc = K×P₁ with an upstream side pressure assumed as P₁ when the flow velocity of a fluid passing through an orifice 4 is at the velocity of sound. The controller is characterized in that an upstream side pressure sensor comprises a resistance element whose electrical resistance varies under pressure and this resistance element as the pressure sensor is simultaneously used as a temperature sensor. In this resistance element, four resistors 41a to 41d are disposed on a pressure receiving surface to form a bridge circuit using the four resistors as four sides. A constant-current power supply 43 is connected between input terminals 42a and 42b of the bridge circuit. A voltage V_p between output terminals 44a and 44b is used to detect a fluid pressure P while a voltage V_T between the input terminals is used to detect fluid temperature T, thus causing the resistance element to function as a pressure-temperature sensor 10.;COPYRIGHT: (C)2004,JPO