Deadweight testers are used as the basic primary standard and its principle is accepted all over the world for the most accurate pressure measurements.
No other piece of equipment for pressure measurement can match the stability, repeatability and accuracy of the deadweight tester. It is ideal for calibrating pressure transducers, pressure gauges, transfer standards, recorders, digital calibrators, etc. and can also be used to measure the pressure directly in systems and processes where precise measurements are important.
A deadweight tester is based on a high accurate manufactured piston and cylinder assembly. This cylinder is mounted in a column. The piston can rotate and freely move up and down. Accurately calibrated masses are loaded on top of the vertically mounted piston.
A pressure is applied on the bottom of the piston to lift the piston with masses. This creates a balance between the downward force made by the masses and the upward force made by the pressure. With the known effective area of the piston the pressure can be calculated. In formula: