Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M3/00—Investigating fluid-tightness of structures
  • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
  • G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
  • G01M3/20—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material
  • G01M3/202—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material using mass spectrometer detection systems
  • G01M3/205—Accessories or associated equipment; Pump constructions
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
  • G01L19/06—Means for preventing overload or deleterious influence of the measured medium on the measuring device or vice versa
  • G01L19/0627—Protection against aggressive medium in general
  • G01L19/0654—Protection against aggressive medium in general against moisture or humidity
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D19/00—Axial-flow pumps
  • F04D19/02—Multi-stage pumps
  • F04D19/04—Multi-stage pumps specially adapted to the production of a high vacuum, e.g. molecular pumps
  • F04D19/046—Combinations of two or more different types of pumps

Definitions

• the invention relates to a sniffer leak detector with a mass spectrometer and with a sniffer probe for analysis of helium or hydrogen.
• Known sniffer leak detectors are used to detect gas leaks, wherein a sniffer probe sucks the gas to be analyzed and supplies it to a detector capable of detecting individual gas constituents in the aspirated gas.
• Sniffing probes are known for example from WO 2009/033978 AI. There, a sniffer probe is described, which supplies a sample gas flow of about 300 sccm a test gas sensor. If necessary, to increase the distance sensitivity, the sniffer probe under Addition of a second suction line, a gas flow of about 3000 sccm are generated. From this gas stream, the sample gas stream branches off at 300 sccm. The sample gas stream is fed to a membrane permeable to test gas.
• WO2010 / 094582 AI describes the basic principle to connect the suction of a sniffer probe via a blocked throttle with the intermediate inlet of a vacuum pump.
• this document is nothing to be inferred in terms of a multiple suction lines having sniffer probe according to the preamble of claim 1.
• mass spectrometers for the analysis of helium or hydrogen.
• the mass spectrometers are connected to a turbomolecular pump whose outlet is connected to a backing pump and whose inlet is supplied with the sample gas flow.
• the sample gas flow may only be about 50 sccm for technical reasons.
• mass spectrometric leak detectors are used in a vacuum, because there the small sample gas flow of 50 sccm is sufficient.
• the conventional mass spectrometric leak detectors are not suitable because the measurement gas flow of the sniffer probe of about 300 sccm is too large for the inlet of the turbomolecular pump and the mass spectrometer.
• the invention has for its object to provide a mass spectrometric leak detector for sniffing leak detection with variable suction currents of the sniffer probe.
• the sniffer corner finder according to the invention is defined by the features of claim 1.
• the mass spectrometer is connected to a sniffer probe having a plurality of suction lines for aspirating the gas to be analyzed.
• the sniffer corner finder is operated with a vacuum pump having at least three stages, whose input stage forms the backing pump for the turbomolecular pump and whose further, subsequent stages serve to provide the variable, selectable suction flow for the sniffer probe.
• the input stage is connected via a blocked throttle to the outlet of the turbomolecular pump to produce a stable backing pressure.
• the blocked throttle at the outlet of the turbomolecular pump preferably produces a gas flow of about 30-70 and in particular of about 50 sccm.
• each intermediate inlets are provided which suck different sized gas streams.
• Each of the intermediate inlets is connected to another suction line of the sniffer probe.
• the intermediate inlet behind the input stage and before the subsequent stage generates the sample gas flow for the sample gas line of the sniffer probe.
• this measurement gas flow is about 200-400 sccm and preferably about 300 sccm.
• the line leading to the inlet of the turbomolecular pump is branched off, in which also a blocked restrictor may be provided to produce the required mass spectrometer input current of typically about 50 sccm (between 30 and 70 sccm).
• the next intermediate inlet produces a larger gas flow, preferably in the range between 2000 and 4000 sccm and advantageously about 3000 sccm.
• This intermediate inlet with the larger gas flow is connected to another suction line of the sniffer probe.
• This intermediate inlet can optionally be switched on or opened to produce a larger intake flow at the inlet of the sniffer probe.
• the lower intake flow for the sample gas line of about 300 sccm is diverted.
• By “about” is present a deviation of max. Meant +/- 10% of said value.
• the vacuum pump is a four-stage vacuum pump, wherein the first two stages are connected in parallel and form the backing pump for the turbomolecular pump. The thus achieved greater pumping speed is necessary to generate the lowest possible pressure behind the diaphragm at point B to ensure the blocking of the flow through this panel.
• the invention makes it possible to use a sniffer probe with several suction lines for mass spectrometric leak detection.
• the multi-stage vacuum pump generates both the partial gas flows for the various suction lines of the sniffer probe and the fore-vacuum pressure for the turbomolecular pump of the mass spectrometer.
• a separation between the backing pump and the pumping stages for the partial gas flows of the sniffer probe is not required, because the input stage is connected to the turbomolecular pump via a throttle which blocks the gas flow and thus produces a sufficiently stable gas pressure for the test gas detection.
• the larger gas flow for the sniffer probe is switched on or off, the gas load acting on the turbomolecular pump does not change, or at least negligibly.
• the pressure fluctuations by switching on or off the various suction lines of the sniffer probe thus do not act on the form in the output line of the turbomolecular pump.
• the multiple suction lines of the sniffer probe one may be formed as a sample gas line for sucking the gas to be analyzed. This sample gas line is then connected to the turbomolecular pump of the Mass spectrometer connected. The remaining suction lines of the sniffer probe can then serve to vary the gas flow to which the sample gas line removes the gas to be analyzed. By adding one or more suction lines, for example, the gas flow can be increased. Alternatively, it may also be possible to select one of a plurality of suction lines and to connect them as a sample gas line to the turbomolecular pump. In this case, only one of the multiple suction lines is operated in each case.
• FIG. 1 shows a block diagram of the embodiment.
• a mass spectrometer 12 is conventionally connected to a turbomolecular pump 14 for mass spectrometric gas analysis.
• the turbomolecular pump 14 has an inlet 16 and an outlet 18. At the inlet 16 and at the outlet 18 is in each case a gas flow of about 50 sccm.
• the outlet 18 is connected to a backing pump 20.
• the backing pump 20 is formed by the input stage 22 of a multi-stage vacuum pump 28.
• the vacuum pump 28 is in four stages, wherein the first two stages 30, 32 are connected in parallel and form the input stage 22. Between the input stage 22 and an intermediate stage 24, a first intermediate inlet 34 is formed. Between the intermediate stage 24 and the output stage 26, a further intermediate inlet 36 is formed. Each of the pump stages 30, 32, 24, 26 consists of a diaphragm pump.
• the first intermediate inlet 34 is connected to the sample gas line 38 of a sniffer probe.
• the sample gas line 38 is a first suction line of the sniffer probe.
• Another suction line 40 of the sniffer probe is connected to the second intermediate inlet 36.
• the output stage 26 generates at the second intermediate inlet 36 and in the second suction line 40 of the sniffer probe a gas flow of about 2700 sccm.
• the intermediate stage 24 generates at the first intermediate inlet 34 and in the measuring gas line 38 of the sniffer probe a gas flow of about 300 sccm.
• the sample gas line 38 is connected to the first intermediate inlet 34 via a restrictor 42 blocking the gas flow in order to create stable pressure conditions at the distribution of the gas stream from the sample gas line 38.
• the partial flow supplied to the inlet 16 of the turbomolecular pump is guided through a further blocking throttle 44 in order to generate and keep the gas flow of about 50 sccm required for the inlet 16 of the turbomolecular pump 14 and the mass spectrometer 12.
• the larger gas flow of the second suction line 40 guided through the second intermediate inlet 36 can optionally be switched on at the sniffer probe in order to create a large intake flow at the inlet of the sniffer probe of approximately 3000 sccm. From this intake flow, the sample gas line 38 takes the sample gas partial stream of about 300 sccm.
• the outlet 18 of the turbomolecular pump is connected via an interlocking throttle 46 with the backing pump 20, that is to say therefore connected to the inlet stage 22 of the vacuum pump 28. With the help of the throttle 46 is at the outlet 18 of the turbomolecular pump 14 to a sufficiently stable gas pressure or gas flow, which is not affected by the optional connection or disconnection of the second suction line 40 to the sniffer probe.
• blocking is meant in the chokes 42, 44, 46, that the throttle generates a stable gas flow, which does not exceed a predetermined value, regardless of the prevailing pressure and flow conditions.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Examining Or Testing Airtightness (AREA)
• Non-Positive Displacement Air Blowers (AREA)
• Other Investigation Or Analysis Of Materials By Electrical Means (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (2)

Family

ID=51539242

Family Applications (1)

Country Status (7)

Cited By (1)

Families Citing this family (12)

Family Cites Families (45)

• 2013
  • 2013-09-16 DE DE201310218506 patent/DE102013218506A1/de not_active Withdrawn
• 2014
  • 2014-09-02 WO PCT/EP2014/068582 patent/WO2015036282A2/de not_active Ceased
  • 2014-09-02 CN CN201480048598.XA patent/CN105556272B/zh active Active
  • 2014-09-02 JP JP2016541879A patent/JP6375378B2/ja active Active
  • 2014-09-02 BR BR112016005378-8A patent/BR112016005378B1/pt active IP Right Grant
  • 2014-09-02 EP EP14765891.8A patent/EP3047250B1/de active Active
  • 2014-09-02 US US15/021,054 patent/US9810597B2/en active Active

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