Mass Flow Leak Test Application with Unique Fixture Design
Heat-exchanger Sample Part
- Two sizes of heat-exchanger segments are proof-tested at 70-110 psig for seam integrity, then leak-tested to a limit of 272 sccm under 30 psig at a rate of 75 pph.
- Test fixtures must pressurize these parts through the larger ring’s open ID while sealing off the smaller ring’s ID, a requirement complicated by the instability of their flexible, thin-metal sealing surfaces.
- InterTech’s design answers the sealing challenge with a pneumatic, multi-jaw chuck that expands outward from the circular fixture holding each ring, wedging into the ring’s open ID to support both sidewall sealing surfaces simultaneously from the inside.
- To avoid the need for high sealing forces to counteract test pressures, sealing fixtures on both sides of the ring automatically grip each other with a bayonet-type twist lock. An inner O-ring seal isolates most of the circular fixture’s central area from the test circuit, confining test pressures to the outer edge of the fixture. This also speeds the test by reducing the test cavity volume and eliminating fixture creep.
- An InterTech M-1075 Mass Flow Leak Detector applies proof pressure for five seconds, then vents the part and applies leak-test pressure for 10 seconds.
- Rejected parts are marked red and remain sealed under pressure so the operator can spray the part with a liquid solution to locate the leak before manually releasing it for rework.
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