Vacuum chamber (inside-out)
The part is filled with helium and placed in a chamber that is pumped to vacuum. Any helium leaking out is drawn to the detector. This gives one accurate total leak rate for the whole part and is the usual choice for production pass/fail testing of coils, tanks, castings and battery components.
Outside-in
The part itself is evacuated and connected to the detector, while helium is applied to the outside, either in a hood or by spraying. It suits parts that can't be pressurised or are tested as vacuum vessels.
Sniffer
The part is pressurised with helium and an operator or robot moves a sniffer probe over joints and welds. The detector signals when it meets escaping helium, which shows exactly where the leak is. Sniffing is less sensitive than vacuum methods but ideal for locating leaks for repair.
Accumulation
The pressurised part sits in a closed hood at atmospheric pressure. Leaking helium builds up in the hood over a set time and is then measured. It avoids the cost of a hard-vacuum chamber for large parts where moderate sensitivity is enough.
Choosing a method
Most production lines use a vacuum chamber for the pass/fail decision and a sniffer station to locate leaks on rejected parts. We'll recommend the combination that matches your leak limit, part size and cycle time.