Impulse Line Blocking Diagnosis of Digital differential pressure transmitter

Abstract

Differential pressure transmitter with an orifice has achieved great field performance and success in flow measurement as a reliable field flow meter. However, blockage in impulse line attached to transmitter is sometime caused by precipitating or solidifying liquids. The pressure signals have random fluctuation signals due to a turbulent flow in a pipeline, and in case of impulse line blockage, the fluctuation signals vary from that of normal conditions. Mean square of differential pressure fluctuation has formerly been used to evaluate the blocking state. However, mean square of differential pressure fluctuation is strongly affected by flow rate. Then we have developed a new diagnostic technique, in which a specific parameter F called ` Blockage factor' indicates the extent of each impulse line blockage. Dp transmitter EJX series is able to measure not only the differential pressure but also the static pressure at high and low pressure sides of orifice by means of Silicon resonant pressure sensor. EJX makes it possible to calculate statistical variables F by using three pressure signals. We confirmed that blockage can be detected by using statistical variables F. Thus, Impulse line blocking diagnosis of digital differential pressure transmitter contributes to predicting blockage in impulse line and saving maintenance cost.