Helium Leak Detectors

In vacuum mode a well-maintained instrument resolves down to the 1x10⁻¹² Pa·m³/s range; in sniffer mode the practical limit is several orders coarser because the probe samples ambient air. The specification only holds after calibration against a known leak standard and with a clean, dry test object.

Vacuum mode when the part can be evacuated and you need the total leak rate with the best sensitivity. Sniffer mode when the part is pressurised with helium and you need to locate the leak, or when the part cannot be pumped down. Many production lines use both: vacuum mode to accept or reject, sniffer to find the spot.

Calibrate against an internal or external standard leak at least at the start of every shift, and again after any filament change, ion source cleaning or transport. Quality systems generally also require an annual calibration of the standard leak itself, because its emission rate drifts with time and temperature.

Yes — ion source filaments, electron multipliers, analyser cell parts, calibrated leaks, sniffer probes and filters, valve bodies and solenoid valves for the common ASM, ASI, Modul and UL families. Send the instrument model and the part number; compatible parts are labelled as compatible and genuine parts are labelled as genuine.

Usually helium already dissolved in elastomer seals or trapped in the test object from a previous test, an internal leak in the instrument's own valve block, or a saturated ion source after a large helium spill. Let the system pump overnight, retest a known-good part, and if the background still will not fall, the valve block or the ion source needs service.