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 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