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
  • 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
• • 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
  • G01M3/22—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 for pipes, cables or tubes; for pipe joints or seals; for valves; for welds; for containers, e.g. radiators
  • G01M3/226—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 for pipes, cables or tubes; for pipe joints or seals; for valves; for welds; for containers, e.g. radiators for containers, e.g. radiators
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/0004—Gaseous mixtures, e.g. polluted air
  • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
  • G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
  • G01N33/0036—General constructional details of gas analysers, e.g. portable test equipment concerning the detector specially adapted to detect a particular component
  • G01N33/005—H2
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N7/00—Analysing materials by measuring the pressure or volume of a gas or vapour
  • G01N7/10—Analysing materials by measuring the pressure or volume of a gas or vapour by allowing diffusion of components through a porous wall and measuring a pressure or volume difference

Definitions

• the invention relates to a gas sensor for detecting the presence of a trace gas and a method for operating a Gcttcrpumpe for sucking off hydrogen to generate a high vacuum.
• the housing is made of glass and the selectively acting passage is a membrane made of a silicon material, on which an apertured silicon wafer and a heater are arranged.
• a gas pressure sensor which responds to the total pressure of the gas that has entered the housing. In this way, a relatively simple gas pressure sensor may be used instead of a mass spectrometer.
• EP 0 831 964 B1 (Leybold Vakuum GmbH) describes the production of a selectively acting passage membrane for test gas detectors of leak detectors.
• a passage has a disk made of silicon, which forms numerous Gas be trecsflambacn. The passage leads into a vacuum chamber which is connected to a vacuum gauge.
• the invention has for its object to provide a gas sensor for detecting the presence of a trace gas, which is of simple construction and provides high sensitivity and selectivity for the trace gas.
• the gas sensor according to the invention is defined by the patent claim 1. It has a detection chamber having a selectively permeable to the trace gas wall, and a pump chamber containing a trace gas receiving getter pump.
• the detection chamber is connected to the pump chamber through a throttle channel.
• a pressure sensor contained in the detection chamber detects a pressure increase caused by penetration of the trace gas.
• the invention provides that a high vacuum is generated by the getter pump in the detection chamber.
• the getter pump is contained outside the detection chamber in a pump chamber. Once through the selective Only for the trace gas permeable wall trace gas enters the detection chamber, there is an increase in pressure, which can not be degraded immediately by the getter pump by the flow-inhibiting effect of Drossclkanals. This pressure rise is detected by the pressure sensor and can be evaluated as an indication of trace gas detection.
• the increased pressure in the Detekt ⁇ onshunt is degraded delay, taking into account the caused by the throttle channel time constant, so that the gas sensor is then ready to function again.
• the gas sensor is configured to detect the presence of hydrogen.
• the Druckse ⁇ sor contained in the detection chamber supplies a current that is dependent on the gas pressure.
• a Penning pressure sensor includes two plate electrodes as cathodes and an anode ring interposed therebetween. When gas ions are in the space between the anode and the cathode, they generate a detectable current. In this way, very low gas pressures of less than IGT 12 measurable measurable, but with very small measuring currents in the order of 10 "13 A. In this way, a high sensitivity of trace gas detection can be realized Penning measuring cells are available from Inficon available under the name "Penning Gauge PEG 100".
• the detection chamber is delimited by a wall which is selectively permeable only to the trace gas, only the trace gas can enter the detection chamber from the outside.
• the occurrence of a change in pressure in the detection chamber is used to detect the introduction of trace gas and the erfindungsdorfc gas sensor suitable for the detection of the smallest trace amounts of gas because a high vacuum can be generated mbar in the order of 10 "12 with the getter pump.
• the pressure sensor used for gas detection is considerably easier than a mass spectrometer does not need to react selectively to a particular gas. Rather, it is sufficient if the total pressure in the detection chamber is determined. In this case, no absolute value determination is required, but it is sufficient to determine pressure changes.
• the wall which is selectively permeable to the trace gas but retains other gases, consists of a membrane supported on a support, e.g. made of silicon, is arranged.
• the selectively permeable wall is heatable to increase the permeability.
• the membrane itself can be used as a heating resistor.
• the invention provides a simply constructed gas sensor which can detect even the smallest partial pressures of the sample gas by simple means.
• the gas sensor is particularly suitable for use in leak detection, wherein the leakage of the trace gas is detected from a container.
• the invention further relates to a method for propelling a getter pump for aspirating hydrogen, according to claim 7.
• a hydrogen adsorbing getter in an evacuable vessel having a hydrogen-selectively permeable wall is heated to regenerate, so that Hydrogen from the getter material escapes through said wall into the atmosphere.
• the getter material forms a regenerable hydrogen pump.
• the method exploits the fact that when the getter heats up, hydrogen previously adsorbed migrates to the surface of the getter material so that the hydrogen outgases outwards. The other gases, on the other hand, diffuse into the getter material when heated.
• equilibrium is established between the uptake and release of H 2 molecules. "The uptake is depending on the external pressure (partial pressure). The delivery depends on the temperature. When the getter material is heated, hydrogen is released from this material and fills the space of the vessel. This increases the partial pressure of the hydrogen in the vessel above the partial pressure in the surrounding atmosphere. Hydrogen therefore exits the vessel into the atmosphere. This means a regeneration of the getter material, which is freed from hydrogen in this way. The getter material is then receptive to new hydrogen to be pumped.
• Figure 1 is a schematic representation of a gas sensor for determining the
• FIG. 2 shows a regenerable getter vacuum pump for pumping
• FIG. 1 shows a gas sensor for a total pressure-independent hydrogen partial pressure measurement.
• the gas sensor has a closed housing 10 made of glass, which contains a detection chamber 11.
• a wall 12 of the housing also consists of a carrier of porous silicon, which is bonded to the glass of the housing.
• This support is covered with a thin membrane 13 made of palladium. Palladium has the effect of permeating only hydrogen and its isotopes (H 2 , D 2 , T 2 , HD, HT and DT). For all other elements, the permeability is negligible.
• a pressure sensor 14 in the form of a Penning pressure sensor.
• the pressure sensor 14 has two parallel Katodcnplatt- en 15, which are arranged at a mutual distance, and of which in Figure 1, only one is visible. Between the cathode plates 15 is an anode ring 16, whose axis is orthogonal to the plate plane. A voltage source 17 provides the DC voltage, the plates between the cathode and the anode ring is placed. In the circuit is a current measuring device 18 for measuring the cathode or anode current. The necessary for Penn ⁇ ngentladung magnetic field is generated by a mounted outside of the closed housing 10 permanent magnet.
• the cathode plates 15 of the pressure sensor 14 are made of a material which has the lowest possible suction effect for hydrogen, e.g. Aluminum. This ensures that the cathode surface is not enriched with hydrogen during operation. Thus, a constancy of the pumping speed is given, which is determined almost exclusively by the getter pump 30.
• a getter pump 30 is connected via a throttle channel 20, which generates a high vacuum in the detection chamber 11.
• the getter pump 30 has, in a sealed vessel 31 made of glass, a chamber 32 which contains a getter material 33.
• the getter material consists for example of the getter ST707 of the manufacturer SEAS-Gctters. It has a great adsorption effect on hydrogen. The hydrogen is therefore pumped out of the detection chamber through the throttle passage 20.
• the detection chamber 11 is first evacuated through an intake manifold 35, and then sealed so that there mbar in the detection chamber, a vacuum of for example 10 "8 to 10 '7. Then, the getter material of the getter pump 30 becomes the activation temperature of z, B. 500 0 C heated so that the getter pump 30 Siphons hydrogen from the detection chamber 11 and the hydrogen Partiaiyak reduced to pressures less than 10 12 mbar. If hydrogen from the atmosphere enters the detection chamber 11 through the hydrogen-selectively permeable heated wall 12, the pressure in the detection chamber 11 increases because the hydrogen can only be sucked off through the throttle passage 20 with a delay. This pressure increase is detected by the pressure sensor 14 and evaluated as penetration of hydrogen.
• FIG 2 shows a getter pump 50, which is in principle formed in the same way as the Gettcrumpe 30 of Figure 1.
• the getter material 52 is in the form of numerous getter pills 53, which are held by a grid, the getter is a non-evaporable IMEG material (non-evaporatable getter). These are materials whose pumping action is started by heating. Gases adhere to the surface of the getter and diffuse during heating in the interior of the individual getter particles, so that subsequently the reactive surfaces of Getterpart ⁇ kel can accommodate other molecules. This process is repeatable until the solid state material reaches the saturation limit. Only for noble gases and hydrogen is this process different.
• NEGs show for inert gases, due to the inert behavior of the noble gases, no pumping action. Hydrogen is weaker bound by the getter than other reactive gases. For hydrogen there is an equilibrium pressure to the environment, which depends on the getter temperature and the amount of hydrogen absorbed by the getter. After absorption of large amounts of hydrogen, the suction effect can not be renewed by heating, without auser outgassing hydrogen is removed during heating.
• the getter material used in the present case is the getter ST707 from the manufacturer SEAS-Getters. Other NEG materials may be used.
• the vessel 51 is closed on one side by a thin heatable membrane 54 of palladium.
• Palladium has a high permeability exclusively for hydrogen and its isotopes.
• the getter pump 50 acts through the membrane 54 for hydrogen.
• the vessel 51 is first evacuated once to prevacuum pressure and then sealed.
• the getter is set to e.g. Heated to 500 ° C, so that the getter effect is started.
• the active state of the getter material all reactive gases adhere to the surface.
• hydrogen can flow through the palladium membrane 54. Accordingly, only hydrogen is pumped from the environment of the vessel 51 from the hydrogen pump. The pump acts only for hydrogen regardless of the partial pressures of other gases in the environment.
• the volume is evacuated once to p ⁇ 10 " mbar and finally closed by pulling laps, then the getter is activated by heating so that atmospheric gases present in the closed volume are pumped and hydrogen is also adsorbed on the getter material In this state, only hydrogen is pumped from the environment of the pump, because only this is due to the - D -
• Palladium membrane can flow into the pump volume. This is the normal operating condition.

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• General Physics & Mathematics (AREA)
• Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Immunology (AREA)
• General Health & Medical Sciences (AREA)
• Biochemistry (AREA)
• Analytical Chemistry (AREA)
• Pathology (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Food Science & Technology (AREA)
• Medicinal Chemistry (AREA)
• Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
• Separation Using Semi-Permeable Membranes (AREA)
• Examining Or Testing Airtightness (AREA)
• Other Investigation Or Analysis Of Materials By Electrical Means (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=35106658

Family Applications (1)

Country Status (6)

Families Citing this family (17)

Citations (1)

Family Cites Families (14)

• 2004
  • 2004-07-16 DE DE102004034381A patent/DE102004034381A1/de not_active Withdrawn
• 2005
  • 2005-07-12 US US11/632,112 patent/US20080202211A1/en not_active Abandoned
  • 2005-07-12 EP EP05766817A patent/EP1769226A1/de not_active Withdrawn
  • 2005-07-12 JP JP2007520829A patent/JP2008506936A/ja active Pending
  • 2005-07-12 WO PCT/EP2005/053321 patent/WO2006008253A1/de active Application Filing
  • 2005-07-12 CN CNA2005800238042A patent/CN1985159A/zh active Pending

Patent Citations (1)

Non-Patent Citations (1)

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