Push-pull connectors are widely used where fast mating, compact design and dependable locking are required. In medical equipment, aerospace systems, defense electronics, energy equipment and vacuum instrumentation, however, mechanical connection alone is not enough. The connector may also need to limit the movement of gas or moisture across housing joints, contact interfaces, sealing elements and potted terminations.

To evaluate these fine leak paths more precisely, MOCO has introduced a helium mass spectrometer leak detector. Unlike visual bubble testing or basic pressure-decay checks, helium tracer-gas testing can produce a quantitative leakage-rate measurement and help engineers distinguish small leak paths that may be difficult to identify with conventional methods.

Why helium leak testing matters for sealed connectors

A connector assembly may contain several potential leakage paths: the shell-to-insulator interface, contact feedthroughs, potting material, O-rings, housing joints and the mating interface. The actual sealing performance depends on the complete construction, manufacturing process, pressure differential, temperature and installation condition.

Helium is useful as a tracer gas because it is inert and can be selectively detected by a mass spectrometer. ISO 20485 describes tracer-gas leak-testing techniques using a tracer-gas-specific detector. By adding this capability, MOCO can move from a simple visible “leak/no-leak” observation toward measured, comparable data under a defined test method.

Inside the MOCO test process

1. Application-specific fixture preparation

MOCO engineers design or select a fixture around the connector geometry and the intended test direction. The fixture and connections must first be evaluated so their own background leakage does not distort the product measurement.

2. Helium exposure and vacuum measurement

Depending on the connector construction, the test can be configured so helium is introduced on one side of the potential leak path while the opposite side is connected to the detector under vacuum. The exact method, pressure differential, exposure time and stabilization sequence must be defined in the test plan.

3. Stabilization, measurement and documentation

The system is zeroed and allowed to stabilize before the measured leakage rate is assessed. The test record should identify the sample, fixture, method, pressure conditions, instrument status, acceptance limit and final measured result.

Initial demonstration: Y Series push-pull connector

The first demonstration featured a MOCO Y Series push-pull connector. The series uses a push-pull locking design and is available in sealed configurations for demanding applications. During the demonstration, engineers connected the sample to a dedicated fixture, established the vacuum test condition and monitored the detector display as the reading stabilized.

Helium leak rate and IP67/IP68 are not the same measurement

IP67 and IP68 describe protection against dust and water under specified ingress-test conditions. Helium mass spectrometer testing measures gas leakage using a tracer-gas method. Helium testing can provide valuable quantitative evidence when developing a sealed connector, but a helium result does not automatically grant an IP rating—and an IP rating does not define a universal helium leakage rate.

For a rigorous qualification plan, engineers should define both the environmental protection requirement and, where needed, a separate maximum allowable gas leakage rate.

From equipment investment to engineering value

The new detector gives MOCO a faster feedback loop between sealing design, fixture development, potting processes, assembly control and customer application requirements. Engineers can compare design iterations, investigate leakage locations and document measured results before a product enters volume production.

For OEM projects, MOCO can review the operating medium, pressure differential, temperature range, installation method, target leakage rate and applicable standard, then discuss whether internal verification or independent third-party testing is appropriate.

Information needed for an application-specific test

• connector and cable-assembly configuration;
• gas or liquid medium and direction of pressure;
• working and test pressure differential;
• target maximum leakage rate and units;
• test temperature and stabilization requirements;
• vacuum, spray, accumulation or other requested method;
• sample quantity and production-inspection frequency; and
• applicable customer, industry or regulatory standard.