Deadweight tester
{{Short description|Device for checking the accuracy of a pressure gauge}}
{{refimprove|date=November 2019}}
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 :
| style="margin:0.2em auto" cellspacing=2 cellpadding=10
| Valign=top align=left | p | Valign=top align=center nowrap | = | Valign=top align=left | F / A | Valign=top align=left | [Pa] |
where :
| style="margin:0.2em auto" cellspacing=2 cellpadding=0 |
| Valign=top align=left | p
| Valign=top align=center nowrap | : | Valign=top align=left | reference pressure | Valign=top align=left | [Pa] |
| Valign=top align=left | F
| Valign=top align=center nowrap | : | Valign=top align=left | force applied on piston | Valign=top align=left | [N] |
| Valign=top align=left | A
| Valign=top align=center nowrap | : | Valign=top align=left | effective area PCU | Valign=top align=left | [m2] |
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 :
- gas operated gas lubricated PCU's
- gas operated oil lubricated PCU's
- oil operated oil lubricated PCU's
See also
{{Commonscat|Deadweight testers}}
References
{{reflist}}