Backpressure in a high-lift compensated pressure relief valve subject to single phase compressible flow

Abstract

Certified pressure relief valves may be used to prevent pneumatic explosion of pressurised systems. Previous published work has highlighted an allowable backpressure limit below which no effect on discharge capacity is noted, and a critical limit at which the valve becomes unstable. These limits are now identified with the normal operating characteristics of a valve (i.e. set pressure, lift, overpressure and blowdown). Tests have been performed on a valve designed to compensate for backpressure and flow characteristics are now presented. Critical backpressure ratio for choked compressible flow is identified, and the effectiveness of the compensation is investigated with respect to lift and discharge capacity. The fundamental physics governing the effect of backpressure is inferred from pressure measurements within the valve. Implications for further design work are stated.