GAS SENSOR AND METHOD FOR DETECTING GAS

Abstract

The invention relates to a gas sensor (34) and a method for detecting gas in a test space (37) of a test chamber for conditioning air, in particular a temperature control chamber, a climate chamber or the like, and to a test chamber, the gas sensor having a sensor head (35) configured to be brought into contact with an atmosphere of the test space. The gas sensor is configured to detect a gas, in particular a refrigerant and/or a hydrocarbon, in the test space, the gas sensor having a transport tube (36) configured to transport a measuring gas from the test space to the sensor head.

Claims

1. A gas sensor comprising a sensor head configured to be brought into contact with an atmosphere of the test space, wherein the gas sensor is configured to detect a gas in a test space of a test chamber, the gas sensor having a transport tube configured to transport a measuring gas from the test space to the sensor head.

2. The gas sensor according to claim 1, wherein the gas sensor is configured to detect the gas in the test space at a temperature in a temperature range from 50 C. to +180 C.

3. The gas sensor according to claim 1, wherein the gas sensor is configured to detect a change in a composition of the atmosphere of the test space.

4. The gas sensor according to claim 1, wherein the gas sensor is calibrated to detect a refrigerant.

5. The gas sensor according to claim 1, wherein the sensor head is configured as a reaction heat sensor or an infrared sensor.

6. The gas sensor according to claim 1, wherein the gas sensor has a pump configured to transport the measuring gas from the test space to the sensor head through the transport tube.

7. The gas sensor according to claim 6, wherein the pump and/or the transport tube is provided with a drain for condensate.

8. The gas sensor according to claim 6, wherein the pump is disposed upstream from the sensor head in the transport tube in a flow direction of the measuring gas.

9. The gas sensor according to claim 1, wherein the gas sensor has a fan the configured to control a temperature of the transport tube with the measuring gas by forced convection.

10. The gas sensor according to claim 9, wherein the gas sensor is provided with a flow channel having an end and a fan disposed at the end, wherein the transport tube is at least partially disposed in the flow channel, and the fan is configured to establish an air flow in the flow channel.

11. The gas sensor according to claim 9, wherein the fan is an axial fan.

12. The gas sensor according to claim 1, wherein the transport tube is at least partially coil-shaped, spiral, or serpentine.

13. The gas sensor according to claim 1, wherein the transport tube is at least partially formed by a metal tube.

14. The gas sensor according to claim 1, wherein the transport tube is formed by a plastic tube at least at an extraction point for measuring gas at the test space.

15. The gas sensor according to claim 1, wherein the transport tube is formed by a plastic tube at least at a return point at the test space.

16. A test chamber comprising: a temperature-insulated test space configured to be sealable from an environment to hold test material, and a temperature control device configured to control a temperature of the test space, the temperature control device being configured to establish the temperature in a temperature range of 50 C. to +180 C. within the test space, the temperature control device having a heating feature and a cooling feature with a cooling circuit containing a refrigerant, a heat exchanger in the test space, a compressor, a condenser, and an expansion member, wherein the test chamber comprises at least one gas sensor according to claim 1 that is configured to detect refrigerant in the test space.

17. The test chamber according to claim 16, wherein the refrigerant is flammable and/or a hydrocarbon or a refrigerant mixture of hydrocarbons.

18. The test chamber according to claim 16, wherein test chamber comprises a ventilation system having a detector with at least the gas sensor configured to detect a refrigerant in the test space, the detector comprising at least one other gas sensor in a machine room of the test chamber, the machine room being separated from the test space in an air-tight manner.

19. A method for detecting a gas in a test space of a test chamber for conditioning air, the method comprising: transporting a measuring gas from the test space to a sensor head of the gas sensor through a transport tube of the gas sensor, bringing a sensor head of a gas sensor in contact with an atmosphere of the test space, and detecting the gas with the gas sensor.

Description

[0029] Hereinafter, preferred embodiments of the invention will be discussed in more detail with reference to the accompanying drawings.

[0030] FIG. 1 is a schematic illustration of a test chamber in a section view;

[0031] FIG. 2 is a schematic illustration of the test chamber in a perspective partial view;

[0032] FIG. 3 is a schematic diagram of a gas sensor.

[0033] FIGS. 1 and 2 show schematic illustrations of a test chamber 10 with a housing 11, within which a test space 12 and a machine room 13 are formed. A heat exchanger 14 of a cooling circuit (not shown) of a temperature control device of test chamber 10 is disposed in test space 12. A test space fan 15 can be used to circulate air within test space 12 past heat exchanger 14. A valve box 16, in which valves (not shown) of the cooling circuit are integrated, is disposed in machine room 13. Valve box 16 is open toward machine room 13. Furthermore, a condenser 17 and a compressor 18 of the cooling circuit are disposed in machine room 13. Openings 19 and 20 for ventilating machine room 13 are formed in machine room 13. Another gas sensor 22 of a detector (not shown) is disposed at a bottom 21 of machine room 13. Moreover, a ventilation system 23 is provided in machine room 13. Ventilation system 23 comprises a fan 24 and an exhaust duct 25, which is connected to test space 12. Fan 24 can transport air from test space 12 into exhaust duct 25 when refrigerant, in particular a hydrocarbon or a refrigerant mixture of hydrocarbons, is detected in test space 12 or in machine room 13 by a gas sensor (not shown) in or on test space 12 or by other gas sensor 22.

[0034] Fan 24 comprises a fan motor 26 and a fan impeller 27, fan motor 26 being disposed in an air-tight enclosure 28. Enclosure 28 is made of sheet metal and disposed within machine room 13. According to the illustration in FIG. 2, ventilation system 23 can comprise another fan 29, which is composed of a fan motor 30 and a fan impeller 33. Fan 29 allows ventilating machine room 13. Fan motor 26 can be a conventional fan motor, which does not have to be configured for operation in explosive atmospheres. Fan 29, on the other hand, is intended for use in explosive atmospheres. Fan 24 and fan 29 are connected to a common duct section 32 of exhaust duct 25. In the case at hand, common duct section 32 runs outside of housing 11 in an environment 33. As a result, a potential explosive mixture of refrigerant and air is located outside of housing 11.

[0035] FIG. 3 shows a schematic view of a gas sensor 34, which can be installed in the test chamber described in connection with FIGS. 1 and 2 as is. Gas sensor 34 comprises a sensor head 35, a transport tube 36 for transporting measuring gas of a test space 37, and a pump 38. Transport tube 36 is partially formed by a copper tube 39, which itself forms a coil 40. At an extraction point 41 for measuring gas in a wall 42 of test space 37, transport tube 36 is formed by a plastic tube 43, which extends from extraction point 41 to coil 40. Furthermore, transport tube 36 is connected to test space 37 at a return point 44 in wall 42 with the result that measuring gas can be transported back into test space 37 via return point 44. Transport tube 36 is also formed by a plastic tube 45 from return point 44 to sensor head 35. Thus, pump 38 can aspirate measuring gas from test space 37 and transport it to coil 44 via extraction point 41 and plastic tube 43 and from coil 44 to pump 38 and then to sensor head 35. After passing sensor head 35, the measuring gas is transported back into test space 37 via plastic tube 45.

[0036] Furthermore, gas sensor 34 comprises a fan 46, which is formed by an axial fan 47. Fan 46 is disposed at an end 48 of a flow channel 49 of gas sensor 34. Coil 40 is disposed within flow channel 49. When fan 46 is operated, an air flow is established in flow channel 49, said air flow controlling the temperature of transport tube 36 and the measuring gas located in coil 40 by forced convection. A temperature of the established air flow essentially corresponds to an ambient temperature of gas sensor 34 or a test chamber, which means that significantly colder or hotter measuring gas from the test space is heated or cooled, a temperature of the measuring gas thus being brought closer to a temperature of the environment. This makes it possible for gas sensor 34 to also detect gases in an atmosphere whose temperature would otherwise damage or affect sensor head 35.