# Wallace & Tiernan pneumatic calibrator

**URL:** <https://forumautomation.com/t/wallace-tiernan-pneumatic-calibrator/2465>\
**Category:** Calibration\
**Tags:** instrumentation\
**Created:** [October 17, 2017, 11:42am UTC](https://forumautomation.com/t/wallace-tiernan-pneumatic-calibrator/2465 "2017-10-17T11:42:31Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![sivaranjith](https://forumautomation.com/letter_avatar_proxy/v4/letter/s/ba9def/32.png) [@sivaranjith](https://forumautomation.com/u/sivaranjith)\
**Post date:** [October 17, 2017, 11:42am UTC](https://forumautomation.com/t/wallace-tiernan-pneumatic-calibrator/2465/1 "2017-10-17T11:42:32Z")

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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.

 ![](https://cdn.forumautomation.com/original/1X/116f6e54a8a5de6256b0e1efd6c8ecf22ba2a812.png)

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