Development of a system for measuring head differential pressure and density of working fluid at high pressures

A system for accurately measuring the head differential pressure between a reference level and a measurement level at high line pressures has been developed. The system mainly consists of a pressure transducer, a motorized slider, a high-pressure flexible metal tube, and pressure generation apparatuses, including a pressure balance. The head differential pressure is obtained from the pressures measured by the transducer at two levels whose vertical distance was varied from 0 mm to 1000 mm. The line pressure was varied from 20 MPa to 200 MPa. The results of our experiments showed that the head differential pressure for a vertical height difference of 1000 mm could be measured accurately as a function of line pressure. From the measured head differential pressure, the density of the working fluid used could be evaluated as a function of pressure up to 200 MPa with a relative expanded uncertainty of 1.3 × 10−2.