# US 5,341,671 A · Helium leak detector

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- Number: US 5,341,671 A
- Document ID: US5341671A
- Status: Granted
- Kind: A
- Application number: 07/949,155
- Filed: 1992-09-23
- Granted: 1994-08-30
- Earliest claimed: 1991-09-24
- Assignees: Alcatel Cit
- Inventors: Gilles Baret; Roland Gevaud
- Web page: https://patentgrep.com/patent/US5341671A

## CPC

- G01M 3/202: {using mass spectrometer detection systems}
- G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR

## 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.

## Claims

### Claim 1

Helium leak detector comprising; a gas analyzer, a dry primary pump, a secondary pump connected in series with said primary pump and comprising at least on a discharge side thereof, a Holweck type stage, said secondary pump comprising means for reducing the suction pressure to a value at least equal to 10.sup.-4 mbar and having a discharge pressure compatible with a suction pressure of said dry primary pump, said dry primary pump comprising at least two stages in series, said secondary pump being connected to a low-pressure output of a sampling unit at an intermediate point on said secondary pump where the flow conditions are molecular, a sniffer probe being connected to a high-pressure side of said sampling unit, and said high-pressure side being further connected to said dry primary pump at a point between said at least two stages thereof, whereby said helium leak detector has a very high level of sensitivity, as well as a very short period of recovery when helium pollution of the detector occurs during a previous inspection of a container having a leak.

### Claim 2 (depends on 1)

Detector according to claim 1 wherein a first stage of said primary pump is a dry vane pump housed in a sealed housing, and said dry vane pump including an outlet opening into said housing, and a second stage of said primary pump having a suction inlet thereof connected directly to said housing.

### Claim 3 (depends on 1)

Detector according to claim 1 wherein said intermediate point is at a pressure of approximately 10.sup.-2 mbars.