Abstract: A method for forming an ultra-thin membrane for use in a chemical analyzer such as a mass spectrometer includes the step of applying a sacrificial blocking layer onto a porous substrate, applying a semi-permeable membrane layer onto the sacrificial blocking layer, and removing the sacrificial blocking layer following cure of the membrane layer. In a preferred version, at least one of the blocking layer and the membrane layer are applied to the porous support by means of spin coating, though other deposition techniques can be employed.

Abstract: A fast method for determining molecular mass using mass spectrometry has the following steps: specifying a first adjusting value (M1) of the mass spectrometer, recording the associated signal amplitude (A1), specifying a second adjusting value (M2) which is different to the first, measuring the associated second signal amplitude (A2), specifying a third adjusting value (M3) which is different to the first (M1) and the second (M2) adjusting value, measuring the associated third signal amplitude (A3), determining a quadratic function containing the measured amplitude values as y-values and the specified adjusting values as x-values, determining the maximum of the quadratic function, wherein the searched adjusting value is determined from the x-value of the maximum.

Abstract: The invention relates to a sniffing leak detector comprising a sniffing line (11) and a feed line (33) that leads to a vacuum pump (16). A distribution point (24) from which a branch line (25) leads to a test gas sensor (15) is provided on the feed line (33). In order for the intermediate pressure (P2) at the distribution point (24) to be independent of feed fluctuations of the vacuum pump (16), a throttle (D2) comprising a supercritically operated orifice (20) is provided between the distribution point (24) and the vacuum pump (16). The pressure drop at the orifice (20) is greater than half the intermediate pressure (P2) at the distribution point (24). The flow at the orifice (20) is thus blocked, wherein the flow (Q) remains constant regardless of changes of the pump pressure (P3). Changes of the intermediate pressure (P2) are thus prevented so that the sensitivity and signal stability of the test gas sensor (15) is unaffected by changes of the pump pressure.

Abstract: A device for identifying refrigerants includes a gas cell, which has a test gas inlet and a test gas outlet, an infrared source that radiates through the gas cell, and at least one sensor that detects the infrared radiation that passes through the gas cell. At least one wide-band filter is provided between the infrared source and the sensor. The passband of the at least one wide-band filter includes the absorption spectra of the refrigerants to be detected and does not include the absorption spectrum of hydrocarbons. The gas cell is connected to a cartridge, which contains the refrigerant to be detected in pure form as a reference gas.

Abstract: In order to determine leakage on a device, which contains gas that can be condensed, an adsorbent is used through which ambient gas of the object is conducted. The adsorbed gas is desorbed by means of actuating an excitation device and fed to a gas sensor containing a mass spectrometer. In this way, minute amounts of leaking gas can be determined by means of accumulation. The method is in particular suited for use in the serial production of refrigeration machines.

Abstract: A leak detection method using a specimen filled with a test gas positioned in front of a suction opening. Air is suctioned along the entire surface of the specimen and takes up test gas in the case of a leak. The test gas is recognized by a test gas detector. According to the invention, full mobility of the specimen is ensured during the testing process so that the leak detection method can be carried out while the specimens are moving past the suction opening.

Abstract: The leak detection device comprises a plurality of measuring cells (10) in whose interior the absorption of a laser beam (17) is influenced by the presence of tracer gas. All of said measuring cells (10) are connected to a host unit (25) via light-conducting fibers (28,34). In the host unit (25), a laser (26) designed for modulation and a photodetector (37) are arranged. Modulation of the laser radiation is preferably performed by two-tone frequency modulation. This has the effect that the fiber length cannot significantly skew the result of the measurement.

Abstract: In order to functionally test a leak detector (20) that comprises a partial pressure sensor (21), a testing device (30) having a variable volume (33) is connected to the leak detector. Said testing device can be a syringe. By changing the volume (33), the partial pressure of the test gas contained in the ambient air is changed. A test is carried out to check whether the leak detector (20) indicates the change. According to the invention, a vacuum pumping device having mechanical vacuum pumps is not required. The method is suitable for testing vacuum systems that contain a vacuum pumping device that is used in the leak test to generate a required vacuum. The service technician can perform the functional test of the leak detector (20) separately from the system and the vacuum pumping device.

Abstract: An ionization vacuum measuring cell has: a) an evacuatable housing (10) with a measuring connection (8) for the vacuum to be measured, b) a first outer and a second inner electrode (3, 4) which are coaxially arranged in an interspaced manner with a common axis (7), whereby a measuring chamber (20) is formed between the two electrodes, the measuring chamber communicating with the measuring connection (8), c) a voltage source (16) which is connected to the electrodes (3, 4), d) a current measuring mechanism (17) for analyzing a discharge current generated between the electrodes (3, 4), and e) at least one permanent magnet ring (1) which surrounds the coaxial electrode (3, 4) arrangement, has a magnetizing direction (13) directed radially to the axis, and has a soft-magnetic yoke (2) that surrounds the permanent magnet ring (1).

Abstract: A leak detector comprises a cell provided with a tracer gas inlet preferably permeable to a tracer gas. In the cell, the tracer gas is caused to assume an energetically higher metastable state. By means of laser spectroscopy the absorption spectrum of the metastable tracer gas is sampled in an optical measuring section, whereby the presence of tracer gas is detected.

Abstract: A sniffing leak detector which comprises a first suction line in a sniffing probe, the line leading to a main device, is provided with a larger second suction line through which gas is sucked in from the sniffing tip by a gas delivery pump. By connecting the second suction line, the distance sensitivity is increased. By disconnecting the second suction line, on the other hand, the sensitivity is increased. Thus, it is possible to first search for leaks by use of a high gas throughput and subsequently exactly determine the leaks under the quantitative aspect by use of a reduced flow.

Abstract: For refrigeration units, maintenance machines are required that can receive and compress the refrigerant from the refrigeration unit. Furthermore, a vacuum pump is required, which is connected to the emptied lines and pumps out humidity and air. The maintenance machine according to the invention includes a motor that drives a compressor via a freewheel in one rotational direction. The same motor drives a vacuum pump via a second freewheel in the other rotational direction. The maintenance machine, which can perform two different functions, includes only one single motor. The machine is lightweight, so that it can be carried by the maintenance personnel. Furthermore, it is small and can be produced in a cost-effective manner.

Abstract: A method for tightness testing, wherein an evacuated test object is exposed to the external influence of a test gas and wherein a gas mixture made of a test gas withdrawn from the test object and of a carrier gas, is examined for the presence of test gas by use of a test gas sensor which, when viewed in the flow direction of the gas mixture, is arranged downstream of a condensing pump for analyzing the compressed gas mixture, wherein the test object is exposed to the ambient atmosphere without being surrounded by a test chamber, and that a test gas gun is provided for generating the atmosphere containing the test gas.

Abstract: A stack (10) of fuel cells (11) is to be tested for tightness of the fuel cell membranes. For this purpose, a tracer gas is introduced into the fuel feed channel (15) of the stack (10). The fuel discharge channel (16) is either open or it is closed. A carrier gas is fed to the feed air channel. (17) and led through the exhaust air channel (18) to a gas sensor (28) where a determination is made whether the carrier gas contains amounts of tracer gas. A defective fuel cell (11) can be located by introducing a lance comprising a sniffing probe into the corresponding channel (18) and determining the position of the probe.

Abstract: A test subject, which is filled with test gas, is placed in a testing chamber, which can be evacuated. A carrier gas is conducted into the testing chamber, so that a gas mixture made of carrier gas and test gas forms therein. The gas mixture is suctioned out of the testing chamber by a compressor pump. A testing gas sensor is connected to the outlet of the compressor pump. The test gas is contained in the compressed gas mixture at a partial pressure which is increased by the compression ratio. In this manner, the sensitivity of the test gas recognition is increased and/or the time constant of the measurement is shortened.

Abstract: The helium sensor comprises a housing that encloses a detection chamber. A side of the housing is closed by a permeable wall that is selective for helium. In the detection chamber, there is located an ion getter pump comprising an anode, a cathode and a magnetic field. The cathode, or a cathode leg is made of beryllium. Beryllium has a low atomic mass, whereby the likewise light-weight helium ions can be better incorporated into the cathode material.

Abstract: A gas pressure measuring cell configuration has a thermal conduction vacuum cell according to Pirani (Pi), with a measuring chamber housing enclosing a measuring chamber and with a measuring connection which channels the gas pressure P to be measured into the measuring chamber. The measuring chamber has a heatable measuring filament connected to an electronic measuring circuitry. The electronic measuring circuitry is in thermal contact on one side of an insulating carrier plate and the carrier plate forms on the opposite side a component of the measuring chamber housing, wherein the measuring filament in series with a measuring resistor (Rm) is supplied directly by the electronic measuring circuitry in feedback and wherein the electronic measuring circuitry directly determines the resistance of the measuring filament.

Abstract: A hydrogen sensor includes a housing, which is closed off by a membrane that is made of palladium and selectively only pervious to hydrogen. The housing is evacuated and contains a Pirani pressure sensor. The membrane and the Pirani pressure sensor are each attached to a carrier. Both carriers are joined directly next to one another or kept at a distance by a connection piece. The hydrogen sensor has a high sensitivity and a low response time due to the relatively large membrane surface and the low housing volume. It can be produced in a small size and integrated in the handle of a sniffer-type leak indicator.

Abstract: The refrigeration compressor is a double-acting refrigeration compressor, comprising a piston which is freely guided on two cylinder sections that are opposite each other and that cannot be moved relative to each other, and which has a flow channel that extends internally through the piston, wherein each cylinder section and the piston have at least one check valve along the flow channel, wherein the check valves are arranged in such a way that the flow directions thereof are oriented in the same direction.

Abstract: The sniffing leak detector comprises a sniffing probe, a suction device and gas detector. An operator-activated switch initiates the beginning of a measuring operation. The switch starts a time measurement, wherein an alarm signal is generated by a signal transmitter at the end of a predetermined measuring period. The sniffing leak detector allows for an operator guidance from measuring point (MP) to measuring point, wherein the measuring period is predetermined and an adherence to the measuring period is monitored.