However, you might face challenges in developing a leak test that is precise, reliable, and consistent. Several factors can affect leak testing, any one of which could produce incorrect results. Hence, you should know the variables affecting the results when checking for any product leakage.
Here are six significant factors that may impact leak testing:
Part’s Stability
Temperature can significantly impact leak testing outcomes. So, you would like a consistent setting with less volatility in temperature and humidity when establishing testing arrangements. Open windows and doors, HVAC systems that blow cold air onto the test station, and even operating fans can affect testing procedures to the point where they provide incorrect results.
For instance, leak testing near open side doors and shipping lanes changes test results. Similarly, if you set your tests in the morning, the results may alter as the testing area heats up from the external plant temperature throughout the day.
Moreover, you must ask the Leak Tester Suppliers to provide coalescent filters to reduce any moisture produced by using compressed gas for testing. These coalescent filters would prevent excess humidity.
Seal and Fixture Design
Defective or incorrectly placed seals without significant stops will affect leak testing. Expect volumetric changes during pressure decay testing if you have floating seals.
Hence, your leak tester supplier must offer the appropriate cylinder size for your pressure test to exert 1.5 to 2 times the opposing force on the component and maintain the seal in a fixed position throughout testing.
Part Variations
Be careful of part porosity or ballooning parts. Porosity can absorb pressure, and ballooning can hide leaks. Invest a little more time filling and maintaining the test pressure to adjust the porosity to fix the problem. Increase your stabilising time to allow a consistent pressure drop during testing. Ensure the parts relax between trials to reduce residual pressure and obtain an accurate result.
Test Cycle Duration
You must ensure sufficient cycle times for reliable testing. You won't be able to tell the difference between a verified good component and an unpredictable rejected part if you do a pressure decay test and don't allow enough stabilised time or test time. Similarly, allow sufficient time to reach a stable vacuum level while using a vacuum leak test.
Device Sensitivity
Ensure the leak tester supplier provides devices precise enough and designed to measure at least 100 times better reject rate. For instance, you won't receive enough test accuracy if you are testing to 20 pounds per square inch (PSI) and are looking for a 2 PSI difference; however, the test apparatus has an analogue gauge that only indicates 2 PSI increments. It is preferable to use a digital meter with a resolution of 1/100 PSI.
Calibration
You must adjust your testing equipment to a leak standard, making a reference point for determining whether or not a part passes leak testing.
There are two fundamental categories of calibration:
Single-point calibration: gives a single precise measurement to a verified leak standard (e.g., an arbitrary zero from a known good part). The reading becomes less accurate the further the results deviate from the calibration value.
Dual calibration: Improves accuracy, allowing you to adjust zero as a pressure change with your verified significant part and obtain a second value for the leak standard. Dual calibration restores the curve and highlights the different testing flow durations.
Final Thoughts
These are just a few of the most common components that affect leak testing results. The only method to accurately test parts for leaks is with proper calibration in a stable testing environment that guarantees consistent results.
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