Instrumentation/Calibration

As a dead weight pressure tester is a secondary pressure calibrator, you will first need to find a pressure calibration laboratory that is recognised to international standards.

Then pay for them to calibrate it.

John.

I am a student of Instrument Technology and very anthusiastic to learn the calibration of Dead Weight Tester.Not learning for commercial use.

Well if its a hypothetical question then the answer would be.

Take your dead weight pressure tester to a temperature controlled environment where there is a primary reference dead weight tester and calibrate it by comparison to that. The primary reference calibrator will need to be calibrated to the relevant international standards to have full traceability.

Noting all the environmental factors such as the local gravity, ambient pressure, humidity and temperature etc...

John.

If you are student, do not take PRESSURE of DEAD weights.

the dead weights are normally in KGf and accordingly can be pre tested /calibrated with certification depending upon the gravity of your place.Now to calibrate the dead weight tester by using these dead weight you can countercheck the results with a pre calibrated Standard/Master pressure gauge from lower value to higher values of dead weights and vice versa.Record all readings and errors observed.Repeat the procedure for 5-6 times.Calculate the avearge deviation/error alongwith repeatibilty and log the same as correction factor for future regular use.

M S Vilkhoo

AGM(Inst)

Siel Chemical Complex(Rajpura):Punjab INDIA

Something I can not agree. Master or other precalibrated gauge doesn't come in picture.

To calibrate really the dead weight pressure guage TESTER,

1. Calibrate the dead weights in comparison to Working standards of weights with certified uncertainty. These working standards need certification from a accredited laboratory, where secondary standards (in turn calibrated wrt national (which in turn calibrated wrt International standard weights)) are maintained.

This comparison with working standars is to be done as many number of times as possible .. may be 30 times. This gives uncertainty of working standards by statistical methods.

2. The area of piston need to be measured using certified micrometer with known uncertainty, number of times. This gives uncertainty of diameter measurement of piston, which gives area of piston.

3. Buoyancy effect needs to be calculated depending up on the location. Effect of atmospheric pressure may also come in picture. Again the uncertainty of barometric pressure.

4. Friction effects need to be calculated.

After calculating all these uncertainties, statistically (Sq. root of sqs added etc), overall uncertainty is to be calculated.

Toooo long a procedure... but must