There are many calibrators can be used to calibrate pressure gauges. But a Wallace & Tiernan pneumatic calibrators is portable and can be used for the calibration both pressure gauges and pressure transmitter. A pressure gauge needs single pneumatic connection, while pressure transmitter needed three pneumatic connection to calibrate. Both kinds of calibration can be achieved by using Wallace & Tiernan pneumatic.
Wallace & Tiernan pneumatic calibrators are mostly used to perform the calibration of control loops instruments in operational plants.
The Wallace & Tiernan pneumatic calibrator needed a constant air supply. This constant air supply is regulated to 0-30 psi.
Main components of Wallace & Tiernan pneumatic calibrator from the above figure:
Air supply input: Connection through which air supply is provided. The maximum air pressure which may safely be applied to the connection is 35 psi only.
Test gauge: The test gauge indicates the actual pressure in the gauge under test.
P1 & P2: P1 and P2 are pressure output connections. The output pressure is regulated to a range 0-30 psi and the pressure is variable, regulated using regulator 1 and 2 respectively.
P3: P3 is an input pressure connection used to measure pressure from external connection and most used to measure the pressure from a pneumatic transmitter.
Regulator 1 & 2: The supply air pressure is directly connected after filter to the regulators. Regulators regulate the output from 0-30psi. Regulators allow applying a known pressure to the pneumatic control.
Selector valve: Allow to select one of any three pressure to be applied to the pressure gauge connection. All the three pressures P1, P2 & P3 are allowed to select and there is a fourth point in selection, which permits venting pressure from the gauge to atmosphere