Deadweight tester



A dead weight tester apparatus uses weights to apply pressure to a fluid for checking the accuracy of readings from a pressure gauge. A dead weight tester (DWT) is a calibration standard method that uses a piston cylinder on which a load is placed to make an equilibrium with an applied pressure underneath the piston. Deadweight testers are secondary standards which means that the pressure measured by a deadweight tester is defined through other quantities: length, mass and time. Typically deadweight testers are used in to calibrate pressure measuring devices.

Formula
The formula on which the design of a DWT is based basically is expressed as follows :

where :

Piston cylinder design
In general there are three different kind of DWT's divided by the medium which is measured and the lubricant which is used for its measuring element :


 * 1) gas operated gas lubricated PCU's
 * 2) gas operated oil lubricated PCU's
 * 3) oil operated oil lubricated PCU's