Pulsation Control in Pressure Metering Systems

Abstract

Reliable pressure measurement in pulsating flow conditions is difficult. When an orifice meter is used, two significant errors can arise: the square root error, which is inherent to orifice plates, and the pressure distortion generated in the sensing lines and DP transmitter. This study is concerned with minimizing pulsation effects in the sensing-recording system. The method used involves predicting the system dynamic characteristic and modifying it so that pulsation excitation frequencies and the resonant frequencies of the system do not coincide. A differential pressure metering system is modelled as a acoustic-mechanical assembly that includes a DP transmitter equivalent piston, its cavities and sensing lines. The acoustic-mechanical interaction is shown for the pressure metering system incorporating a bellows type DP transmitter. The influence of the acoustic and mechanical parameters on the system dynamic characteristic is discussed.