Leak-Test Repeatability: Separate Product Leaks from Fixture Effects
Investigate fixture seals, stabilization and repeatability before treating every failed pressure-decay result as a defective heat exchanger.
China Thermic Editorial Team
A failed pressure-decay result can originate in the product, the test connection or changing test conditions. A repeatability investigation should separate these possibilities before the production team adjusts the acceptance limit or reworks the assembly.
ESTABLISH A CONTROLLED BASELINE
Use the approved reference arrangement to check the tester and fixture. Document the test recipe, connection method, stabilization period and environmental conditions. Follow the equipment supplier's pressure and safety instructions. A reference check is useful only when its condition and expected result are controlled.
EXAMINE THE CONNECTIONS
Inspect seals, locating surfaces and clamp alignment. Look for changes associated with product variation or repeated fixture use. Repeat the connection procedure with representative operators and parts to see whether results follow the connection rather than the product. Keep the sequence and results recorded so intermittent behavior remains visible.
ACCOUNT FOR TEMPERATURE
Pressure readings can change as the product and test gas approach thermal equilibrium. Compare tests performed after consistent conditioning and stabilization. Avoid mixing hot parts directly from production with cooled reference parts and then attributing every difference to leakage.
DEFINE THE DISPOSITION PATH
An unexpected result should trigger a defined check, retest policy and product disposition. Repeated testing until a part passes is not a reliable acceptance method. If a fixture fault is confirmed, review the affected interval using traceable records and the site's quality procedure.
FREQUENT QUESTION: SHOULD THE LIMIT BE LOOSENED TO REDUCE FALSE FAILS?
First establish the source of variation. The acceptance criterion should come from product requirements and the validated method, not from the desired reject rate.
TECHNICAL REFERENCE
NIST's metrological traceability guidance provides context for reliable measurement results. The fixture investigation above is a practical diagnostic checklist. https://www.nist.gov/metrology/metrological-traceability