A deadweight tester is a device used to test the accuracy of a pressure gauge or to calibrate electronic pressure measuring devices. This is done by placing weights onto a piston cylinder to create an equilibrium with pressure forces applied from below.
Deadweight testers are often used in industrial settings where pressure gauges must be calibrated or routinely checked for accuracy. Deadweight testers are primary standards, meaning that the pressure they measure is defined through the quantities of length, mass and time. The weights on a deadweight tester usually spin in order to reduce the affects of friction on the final measurements of pressure.