The study effects of the characteristics of hydraulic oil on calibration of hydraulic pressure balance

摘要

One of the sources of an anomaly in the calibration of a hydraulic pressure balance is a various kind of working fluids that is employed in an operation. Therefore, the pressure and vacuum laboratory at National Institute of Metrology (Thailand), also known as NIMT, has been studied the effects of using different types of working fluids. The purposes of the study are to find piston effective area and study effectiveness of hydraulic pressure balance by observing falling rate and piston rotating time. The studies were performed in two ranges which are between 40 bar to 70 bar, and 600 bar to 700 bar. The results illustrate that the effective area of piston in the range of 40 bar to 70 bar has the maximum difference of 14 ppm, and in the range of 600 bar to 700 bar, it has the maximum difference of 5 ppm which will not affect the accuracy of hydraulic pressure balance. In addition to that, hydraulic pressure balances that use DHS oil have a falling rate approximately double of hydraulic pressure balances that use ISO VG 22 oil. Regardless, this does not affect the calibration result also the usage of the equipment. As the result, these two oils can be used interchangeably in calibration of hydraulic pressure balance that used in industry sector.