Automation of Hydraulic Dead Weight Tester

Dead weight tester is a well known hydromechanical system which utilises Bernoulli's principle to achieve a highest level of accuracy in its class. This makes it a primary standard which is internationally used in calibration laboratories. Hydraulic pressure sensors and reference standards are calibrated using cross float method where the hydraulic Dead weight tester is used as a highest accuracy pressure source/calibrator to maintain calibration traceability chain. Typically a Dead weight tester consists of piston cylinder assembly along with masses, hydraulic compressor with rotary piston, a collector port (where output pressure is made available for device under calibration) and an oil reservoir. Calibration using hydraulic Dead weight tester requires huge human efforts; it becomes more cumbersome when used at high pressure. It requires more man power when it is used to generate pressure at its highest range or near highest range as it is mechanically structured equipment. Taking reading is also a tedious task as it is very difficult to note down results on a sheet during equilibrium when rotation along with mass as it is a part of sequence of operation. The system available at calibration laboratory turned out to be non functional due to leak through compression unit. The acts involved for restructuring the system involved investigating the past limitations, root cause analysis and executing remedial actions, developing software, hardware adaptation etc. to put back the system lucratively into service. The execution approach from rectification to ‘make the system automatic’ is brought out in this paper.