High speed helium leak detection system and method

A high speed He leak detection system comprising:

• a sealed, mobile, purged air enclosure permitting operation of electrical components thereof in Class 1, Division 1, Group D Hazardous Locations;
• said enclosure including a pair of vacuum pumps disposed in parallel drawing a sample stream of gases from a He sniffer probe assembly;
• a first pump located downstream of a He leak detector in said enclosure that is configured to draw a minor portion of said sample stream through said He detector;
• and a second pump configured to draw a major portion of said sample stream and exhaust said major portion without sampling directly to the exterior of said enclosure;
• said dual pump induction of sample stream from said sniffer permitting high speed response of said detector on the order of about 2 seconds for probe sample stream hose line lengths on the order of 60′;
• and a controller disposed in said enclosure for configuration of operation of said leak detection system including presetting a leak rate level for triggering an alarm at said sniffer probe assembly.

A method of high speed detection in hazardous environments of He leaks from vessels pressurized with He tracer gas, comprising the steps of:

• a. pressurizing a vessel to be tested for leaks with a He-containing tracer gas;
• b. sampling selected areas of the exterior of said vessel to be tested with a negative pressure probe to obtain a sample stream volume of gas that may contain He leaking from said test vessel;
• c. transferring to a purged air, sealed mobile enclosure said entire volume of said sample stream;
• said mobile enclosure having disposed therein a manifold connected to a first negative pressure device;
• d. splitting-off at said manifold a minor portion of said entire sample stream as a detection stream;
• e. drawing said detection stream through a He sensor by a second negative pressure device, said He sensor providing a signal upon detection of the presence of trace gas He in said detection stream, and said He sensor and said second negative pressure device being disposed within said mobile enclosure;
• f. converting in near real time said detection signal into quantitative leak rates of said test vessel;
• and
• g. introducing compressed filtered dry air or inert gas other than He into said sealed enclosure to provide an internal overpressure therein to prevent infiltration into said enclosure interior of hazardous vapors from the location where the enclosure is located and permit the use of of electrical components required for said negative pressure and sensor devices.