Density measurement of pressure transmitting oil at high pressures up to 100 MPa by changing the vertical position of a precise pressure gauge

This paper presents a method of on-site density measurement of pressure transmitting medium at high pressures. The density is estimated by precisely detecting head differential pressure using a monitoring pressure gauge. A flexible pressure tube which is durable for high pressures is used to change the vertical position of the monitoring pressure gauge. We measured the density of dioctyl sebacate, which is commonly used as hydraulic pressure transmitting oil for pressure calibrations. The estimated density was almost similar to the previously reported value at low pressures, but became smaller by approximately 1 % at 100 MPa. This method is applicable to other pressure transmitting medium, which are being used at calibration laboratories and industries without accurate density values at high pressures, and will help users to estimate head differential pressure more accurately.