Abstract: A leak detector including at least one analysis unit connected to the inlet of a first secondary pump, a pre-evacuation set connected to an inlet coupling, the inlet of said pre-evacuation set further being connected to the outlet of said first secondary pump via a pipe provided with a first valve, wherein said pre-evacuation set comprises a second secondary pump and a mechanical primary pump connected together in series, and wherein a pipe provided with a second valve connects an intermediate point of said first secondary pump to the inlet of said second secondary pump.

Abstract: A tracer gas leak detector that analyzes a test gas for presence of a tracer gas therein, including at least one gas analyzer, a secondary pump whose suction inlet is connected to the gas analyzer, a primary pump connected to the secondary pump outlet via a first pipe fitted with a first valve, and a second pipe connecting the first pipe from a point situated between the first valve and the primary pump to an inlet of the detector for connection to an enclosure via a pre-evacuated flow and said gas analyzer receiving said test gas from a part of said pre-evacuated flow, the second pipe being fitted with a second valve, the primary pump serving to pre-evacuate the enclosure, wherein a sampling member for sampling the flow travelling along the second pipe is situated directly on the wall of the second pipe in direct contact with the flow and is connected via a duct directly to the analyzer, the sampling member having flow conductance enabling the pressure in the duct to be compatible with operation of the gas a

Abstract: An installation for detecting the presence of helium in a fluid circuit, the installation including a tapping member constituting a volume comprising a first internal space and a second internal space separated from each other by a semi-permeable partition through which helium can pass, the first space of said tapping member being inserted in series in the fluid circuit, the second space being connected both to a gas source via an orifice having an adjustable aperture, and also to a pumping member via a pipe, the flow pumped through the pipe conveying the flow under viscous conditions towards a feed member connected to a helium leak detector.

Abstract: A helium leak detector includes a gas analyzer and a secondary pump having at least on its discharge side a Holweck type stage. The pump is of a type enabling the suction pressure to be reduced to a value at least equal to 10.sup.-4 mbar and a discharge pressure which is sufficiently high to be compatible with the suction pressure of a dry primary pump having at least two stages. The secondary pump is connected to the low-pressure output of a sampling unit on an intermediate point of the secondary pump where the flow conditions are molecular. A sniffer probe is connected to the high-pressure side of the sampling unit. This high-pressure side is further connected to the dry primary pump between its at least two stages.

Abstract: A leak detector comprises helium measuring means (6) for measuring helium sucked in by a sniffer (2) via a flexible hose (3) and a liquid nitrogen trap (5). A vacuum is maintained in the nitrogen trap (5) by a molecular diffusion pump (7) leading to a vacuum pump (18) which exhausts to the atmosphere. In order to speed the flow of gas, possibly including helium as a tracer element, along the flexible hose (3) most of the gas sucked in by the sniffer (2) is diverted from the inlet (4) to the nitrogen trap by a bleeder arrangement (12) connected to an auxiliary duct (11) which is itself connected to an intermediate point between two stages in the vacuum pump (18).