How to calibrate the pneumatic instruments?

HI Vinoth, there are many types of pneumatic instruments. Please be specific which one you want to know about so that you will get a better answer. Generally calibration requires a sourcing instrument, a standard reference instrument and the test meter.

For Pressure Gage: You can calibrate it with standard calibrated Gage with the same range by using oil pressure tester or air pressure tester on the different ranges (0%,%,%,% &% of the range).

For pressure transmitters & Pressure switches you can calibrated too with standard calibrated Gage with the same range by using oil pressure tester or air pressure tester on the different ranges (0%,%,%,% &% of the range).

Calibration is one of the primary process used to maintain instrument accuracy.

To calibrate an instrument involves checking that the out put of the given instrument corresponds to given inputs at several points throughout the calibration range of instruments , although the exact procedure may varry from product to product.

calibrer un instrument de mesuredisposer de l'energie pneumatique , electrique ou hydrauliqueconnecter l'instrument à l'energie d'alimentation et de commadeappliquer dans la chambre de mesure une force de signal equivalente  à 0% de l'echelle  de mesure et regler  le signal de sortie  à la valeur minimale  de l'echelleune force de signal  équivalente à100% de l'echelle de mesure  et regler le signal de sortie à sa valeur maximum de l'echelleune force de signal intermediaire  equivalente à 25% et 50%   pour parfaire la linéarité et regler le signal de sortie correspondant à 25% et 50%200mbar .....1000mbar pour le pneumatique echelle de sortie

alimentation  pneumatique  1400mbar generalement OU 20 PSI

For pneumatic instruments you should have a pressure source (Gas cylinder or pressure pump), with either oil or gas, make sure not using oil for oxygen service instruments.

devide the range and apply pressure atleast five divisions ascending and descending ways. (both should be done to check hysterisis).

record the output and calculate error :)

Seals offer another advantage over wet legsthere is more versatility for mounting the transmitter. The transmitter can be located above the tap. This is particularly helpful when the tank is buried or if the transmitter must be located in a more convenient area. The transmitter can be mounted above the tap as long as the back pressure on the seal does not exceed 1 atmosphere of pressure (33.9 feet). When the seal is above the tap, the level calculation is slightly different because the distance must be subtracted from the level instead of added.

Dear Vinoth, 

There are many pneumatic instruments which are used in measurement and control purpose. All instruments are calibrated in different procedures but principles are same. Calibration of instrument is a form of verification of instrument by using high accuracy instruments (Master Instruments). Please specify instrument you want to calibrate to explain in deep.

Hart Communicator 2500hms. 20.000 loop calibrator. digital pressure calibrator. It is apordable pressure means.

Pour calibrer un instrument pneumatique exemple Transmetteur pneumatique: 1 savoir entendue de l’échelle du transmetteur selon le document du procédé exemple 0-6000mmH2O. Premaration des appareils nécessaires comme Alimentation du transmetteur 1.4bar ; instrument de mesure de la sortie du transmetteur qui est 0.2b - 1bar. c'est a dire 0 mmH2O donne 0.2 Bar et  6000mmH2O donne 1bar puis on vérifie 300mmH2O donne 0.6 bar et pour une bonne linéarité on verifie 25% =0.4b et 75% =0.8.  

This is control valve calibration not transmitter, for control vale calibration we have to used pneumatic source from this source we can give pressure from 3psi to 15 psi.