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Replacing pin gauge testing with a pressure controller and mass flow meter

One of our customers developed a go/no-go test where he would check the diameter of a female fitting to ensure proper engagement of the male counterpart. At the time, he was using a pin gauge to measure the diameter of the test part. This setup was both slow and unreliable, so he contacted Alicat to see if we could devise a test using mass flow rate to replace his pin gauge.

Pin Gauge Testing

Test setup with Alicat mass flow meter and pressure controller

Solution: Pressure control & mass flow measurement

The applications engineering team determined that a gauge pressure controller in conjunction with a mass flow meter would accomplish this goal. The pressure controller was used to maintain a fixed pressure, and the meter was used to measure the mass flow rate of gas going through the fitting. In this setup, the flow rate measured by the meter is proportional to changes in the internal area of the fitting. This means, for example, that a 10% increase in flow rate indicates a 10% increase in the internal area of the customer’s fitting.


After receiving the pressure controller and mass meter, the customer ran a few tests to determine the flow rates corresponding to the no-go tolerances of his parts. Once those were documented, he ran additional tests to confirm that his parts were in spec. After logging his results, he verified that his pin gauge agreed with the pass/fail criteria of the mass flow meter. He was able to successfully test his parts faster and with higher accuracy than he could with his pin gauge setup.

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