Monday, July 12, 2010

pressure gauge calibration using deadweight tester


1. Set up the equipments needed for calibration
note: know first the maximum capacity of the dead weight tester whether it can acommodate the range of the gauge calibrated.
2. prepare the manual and date sheet that will be used for details of the instruments to be calibrated.
some information needed for calibration to be input to data sheet:
. equipment name/id no
.ambient temperature
. relative humidity
.date of calibration
.date of next calibration
3. wrap the gauge fitting of teflon tape in clockwise direction the gauge to be tested to the manifold assembly ( with gauge fitting match to the manifold joint) use correct size of wrench and make sure there is no leak.
5. if the gauge has to be tested has for example 0 to 100 psi range, use the 5 points scale as reading reference.
0% -low pressure ( zero reading)
.100% high pressure
(full scale reading)
here are the i.e of 5 points calibration using zero to 100
[percent_____!___equivalent psi____!________________________________
6. check the pointer intial reading 0 psi. If not, zero adjustment shall be made by adjusting the pinter zero.
7.Place weights on the cylinder corresponding to each point scale of the pressure gauge. increase the actuating pressure equivalent to 0%, 25%,50%,75% and 100% of the assigned range
8. Tightly close the release valve by turning clockwise.
9.Pump gently until it weights floats to an ideal level
10. rotate weights clockwise very gently and continuously while pumping.
11.If cylinder base exceeds above or below the ideal level,, rotate fine pressure adjustment lever.
12. record the pointer indication values for each point scale.
.upscale ( o%,25%,50%,75% and 100%)
.downscale ( 100%,75%,50%25% and 0%)
this is the "as-found data".
13. if the "as found" data exceeds the required accuracy, calibration should be done. a zero or span adjustment must be made.
span = maximum range-minimum range
14. repeat the procedure until the readings for each point scale is within the specified limits of accuracy.
15.record the readings for each point scale and this is the as left date
16. when done, release the built system pressure by opening the release valve
17.put the calibrator sticker.
18.make the calibration certificate with authorize signatures.