Pressure testers are the pressure generation unit for calibrating pressure instruments on comparison method. In this method generally pressure instruments are calibrated against the Master Instrument. Scope of reference calibration is to minimize the time required for calibrating a process pressure instrument. Though as primary standards, Dead weight Testers are the most accurate instruments for the calibration of electronic or mechanical pressure measuring instruments, it requires uploading and downloading of weights for every single increment and decrement, which require more time to calibrate an instrument. In reference calibration, changing of master is required only when the range of the test instrument is changing thus provide faster productivity. Table Top testers are engineered for a different working up to 2000bar. Pressure testers are also can be used for pressure testing of various other components like PRV’s, Safety valves calibration.