pneumatic controller[nu̇′mad·ik kən′trōl·ər]
a controller in which the reactions among the individual elements and the effect on the control member are caused by a change in the pressure of compressed air. Such a controller operates on the principle of using a change in pressure at the output to balance the displacements or forces developed by sensing elements upon a change in the pressure of the compressed air supplied to them. Diaphragms (mainly of the elastic type) or bellows are used as the sensing elements. The power supply of a pneumatic controller is compressed air; the input and output signals are the pressure changes of the compressed air over a standard range of values.
The most common pneumatic controllers in the USSR are those of the AUS (standard unit assembly) and Start pneumatic automatic system, which stabilize parameters at prescribed values, change parameters according to a program, maintain a fixed ratio of two parameters or correct the ratio of two parameters according to a third, and maintain the optimum values of parameters.
Pneumatic controllers are used in automatic control systems for flow rate, pressure, temperature, level, and other parameters of technological processes.
REFERENCESBerezovets, G. T., A. L. Malyi, and E. M. Nadzhafov. Pribory pnevmati-cheskoi agregatnoi unifitsirovannoi sistemy i ikh ispol’zovanie dlia av-tomatizatsii proizvodstvennykh protsessov, 3rd ed. Moscow, 1965.
Sistemy i ustroistva pnevmoavtomatiki [collection of articles]. Moscow, 1969.
G. T. BEREZOVETS