Method and device for testing a temperature-compensated, pressure-gradient-controlled pressure switch

Abstract

Method for testing a temperature-compensated, pressure-gradient-controlled pressure switch, which is pneumatically associated with a primary pressure chamber and comprises a secondary pressure chamber for temperature compensation, wherein, by using at least one temperature-control apparatus between the primary pressure chamber and the secondary pressure chamber, a temperature gradient is set which is sufficiently great to produce a pressure gradient between the primary pressure chamber and the secondary pressure chamber that corresponds at least to the triggering pressure gradient of the pressure switch.

Claims

1. A method for testing a temperature-compensated, pressure-gradient-controlled pressure switch, comprising: providing a temperature-compensated, pressure-gradient-controlled pressure switch, wherein the temperature-compensated, pressure-gradient-controlled pressure switch comprises a secondary pressure chamber, and wherein the temperature-compensated, pressure-gradient-controlled pressure switch is configured to pneumatically interconnect with a primary pressure chamber such that when a pressure gradient between a primary pressure of the primary pressure chamber and a secondary pressure of the secondary pressure chamber is equal to or greater than a triggering pressure gradient, the temperature-compensated, pressure-gradient-controlled pressure switch switches; pneumatically interconnecting the temperature-compensated, pressure-gradient-controlled pressure switch with the primary pressure chamber such that when the pressure gradient between the primary pressure of the primary pressure chamber and the secondary pressure of the secondary pressure chamber is equal to or greater than the triggering pressure gradient, the temperature-compensated, pressure-gradient-controlled pressure switch switches, wherein pneumatically interconnecting the temperature-compensated, pressure-gradient-controlled pressure switch with the primary pressure chamber comprises: interconnecting the temperature-compensated, pressure-gradient-controlled pressure switch with the primary pressure chamber such that at least a portion of the temperature-compensated, pressure-gradient-controlled pressure switch is positioned within the primary pressure chamber; thermally coupling at least one temperature-control apparatus with: the temperature-compensated, pressure-gradient-controlled pressure switch, which is thermally coupled to the secondary pressure chamber; and/or the primary pressure chamber; orienting the primary pressure chamber at a first orientation of the primary pressure chamber, such that a liquid phase of a two-phase filling medium contained within the primary pressure chamber has a first contact surface with the temperature-compensated, pressure-gradient-controlled pressure switch, and wherein the first contact surface is smaller than or equal to a corresponding contact surface of the liquid phase of the two-phase filling medium contained within the primary pressure chamber with the temperature-compensated, pressure-gradient-controlled pressure switch for any other orientation of the primary pressure chamber; and while orienting the primary pressure chamber at the first orientation of the primary pressure chamber, performing, via the at least one temperature-control apparatus, one of more of the following: (i) heating the primary pressure chamber; (ii) cooling the primary pressure chamber; (iii) heating the secondary pressure chamber; and (iv) cooling the secondary pressure chamber, such that a temperature gradient is created between a primary temperature of the primary pressure chamber and a secondary temperature of the secondary pressure chamber that is sufficient to cause the pressure gradient between the primary pressure of primary pressure chamber and the secondary pressure of the secondary pressure chamber to be equal to or greater than the triggering pressure gradient.

2. The method according to claim 1, wherein the method comprises: heating the secondary pressure chamber via a first temperature-control apparatus of the at least one temperature-control apparatus; or cooling the secondary pressure chamber via a first temperature-control apparatus of the at least one temperature-control apparatus.

3. The method according to claim 2, further comprising: thermally coupling a second temperature-control apparatus of the at least one temperature-control apparatus with the primary pressure chamber, wherein the second temperature-control apparatus of the at least one temperature-control apparatus is an active cooling element or an active heating element; and compensating for thermal effects of the first temperature-control apparatus of the at least one temperature-control apparatus on the primary pressure chamber, at least in part, via the second temperature-control apparatus of the at least one temperature-control apparatus.

4. The method according to claim 2, wherein the method comprises: heating the secondary pressure chamber via the first temperature-control apparatus of the at least one temperature-control apparatus, and wherein the method further comprises: thermally coupling a second temperature-control apparatus of the at least one temperature-control apparatus with the primary pressure chamber, wherein the second temperature-control apparatus of the at least one temperature-control apparatus is an active cooling element; and cooling the primary pressure chamber via the second temperature-control apparatus of the at least one temperature-control apparatus.

5. The method according to claim 2, wherein the method comprises: cooling the secondary pressure chamber via the first temperature-control apparatus of the at least one temperature-control apparatus, and wherein the method further comprises: thermally coupling a second temperature-control apparatus of the at least one temperature-control apparatus with the primary pressure chamber, wherein the second temperature-control apparatus of the at least one temperature-control apparatus is an active heating element; and heating the primary pressure chamber via the second temperature-control apparatus of the at least one temperature-control apparatus.

6. The method according to claim 2, wherein the method comprises heating the secondary pressure chamber via the first temperature-control apparatus of the at least one temperature-control apparatus, wherein the method further comprises: cooling the primary pressure chamber via a second temperature-control apparatus of the at least one temperature-control apparatus simultaneously with heating the secondary pressure chamber via the first temperature-control apparatus of the at least one temperature-control apparatus, such that thermal effects of the first temperature-control apparatus of the at least one temperature-control apparatus on the primary pressure chamber are substantially compensated for.

7. The method according to claim 1, wherein the method comprises: heating the secondary pressure chamber via a first temperature-control apparatus of the at least one temperature-control apparatus.

8. A test device for testing a temperature-compensated, pressure-gradient-controlled pressure switch, comprising: at least one temperature-control apparatus, wherein the at least one temperature-control apparatus is interconnected with a temperature-compensated, pressure-gradient-controlled pressure switch having a secondary pressure chamber, wherein the temperature-compensated, pressure-gradient-controlled pressure switch is pneumatically interconnected with a primary pressure chamber such that when a pressure gradient between a primary pressure of the primary pressure chamber and a secondary pressure of the secondary pressure chamber is equal to or greater than a triggering pressure gradient, the temperature-compensated, pressure-gradient-controlled pressure switch switches, wherein the temperature-compensated, pressure-gradient-controlled pressure switch is pneumatically interconnected with a primary pressure chamber so that the temperature-compensated, pressure-gradient-controlled pressure switch is interconnected with the primary pressure chamber such that at least a portion of the temperature-compensated, pressure-gradient-controlled pressure switch is positioned within the primary pressure chamber, wherein the at least one temperature-control apparatus is thermally coupled with: the temperature-compensated, pressure-gradient-controlled pressure switch, which is thermally coupled to the secondary pressure chamber; and/or the primary pressure chamber, and wherein the test device is configure such that the primary pressure chamber is orientable at a first orientation of the primary pressure chamber, such that a liquid phase of a two-phase filling medium contained within the primary pressure chamber has a first contact surface with the temperature-compensated, pressure-gradient-controlled pressure switch, and wherein the first contact surface is smaller than or equal to a corresponding contact surface of the liquid the two-phase filling medium contained within the primary pressure chamber with the temperature-compensated, pressure-gradient-controlled pressure switch for any other orientation of the primary pressure chamber; and wherein, while orienting the primary pressure chamber at the first orientation of the primary pressure chamber, the at least one temperature-control apparatus performs one or more of the following: (i) heats the primary pressure chamber; (ii) cools the primary pressure chamber; (iii) heats the secondary pressure chamber; or (iv) cools the secondary pressure chamber; such that a temperature gradient is created between a primary temperature of the primary pressure chamber and a secondary temperature of the secondary pressure chamber that is sufficient to cause the pressure gradient between the primary pressure of primary pressure chamber and the secondary pressure of the secondary pressure chamber to be equal to or greater than the triggering pressure gradient.

9. The test device according to claim 8, wherein the test device is configured to cause the temperature difference to be at least 10 K between the primary temperature of the primary pressure chamber and the secondary temperature of the secondary pressure chamber.

10. The test device according to claim 8, wherein a first temperature-control apparatus of the at least one temperature-control apparatus: cools a surrounding wall of the secondary pressure chamber in a targeted manner; or heats a surrounding wall of the secondary pressure chamber in a targeted manner.

11. The test device according to claim 10, wherein the first temperature-control apparatus of the at least one temperature-control apparatus heats a surrounding wall of the secondary pressure chamber in a targeted manner, and wherein a second temperature-control apparatus of the at least one temperature-control apparatus cools a surrounding wall of the primary pressure chamber in a targeted manner.

12. The test device according to claim 10, wherein the first temperature-control apparatus of the at least one temperature-control apparatus cools a surrounding wall of the secondary pressure chamber in a targeted manner, and wherein a second temperature-control apparatus of the at least one temperature-control apparatus heats a surrounding wall of the primary pressure chamber in a targeted manner.

13. The test device according to claim 8, wherein the first temperature-control apparatus of the at least one temperature-control apparatus is formed by a silicone heating mat.

14. The test device according to claim 8, wherein a second temperature-control apparatus of the at least one temperature-control apparatus: cools a surrounding wall of the primary pressure chamber in a targeted manner; or heats a surrounding wall of the primary pressure chamber in a targeted manner.

15. The test device according to claim 8, further comprising: a thermal insulation apparatus, wherein the thermal insulation apparatus surrounds an outer surface of the surrounding wall of the primary pressure chamber.

16. The test device according to claim 8, further comprising: a first sensor apparatus, wherein the first sensor apparatus determines a temperature of the surrounding wall of the secondary pressure chamber.

17. The test device according to claim 16, further comprising: a second sensor apparatus, wherein the second sensor apparatus determines a temperature of the surrounding wall of the primary pressure chamber.

18. The test device according to claim 8, further comprising: a detection apparatus, wherein the detection apparatus determines a fill level of a filling medium contained in the primary pressure chamber.

19. The test device according to claim 8, further comprising: a continuity tester, wherein the continuity tester determines a switching state of the temperature-compensated, pressure-gradient-controlled pressure switch.

20. The test device according to claim 8, further comprising: a pressurized container, where the primary pressure chamber is formed by a surrounding wall of the pressurized container.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained in the following on the basis of preferred embodiments with reference to the accompanying drawings, in which:

(2) FIG. 1 shows a first embodiment of a test device according to the invention in which the second temperature-control apparatus is formed by a thermal chamber; and

(3) FIG. 2 shows a second embodiment of a test device according to the invention in which the second temperature-control apparatus is formed by a planar cooling element.

DETAILED DESCRIPTION OF THE DRAWINGS

(4) FIG. 1 shows a first embodiment of a test device 9 according to the invention which is substantially formed by a pressurised container 25, a first temperature-control apparatus 4 and a second temperature-control apparatus 5.

(5) The pressurised container 25 may for example be formed by a fire extinguisher, a primary pressure chamber 2 being formed by a surrounding wall 10. Furthermore, the pressurised container 25 comprises a temperature-compensated, pressure-gradient-controlled pressure switch 1, which comprises a secondary pressure chamber 3. The pressure switch 1 is connected to the surrounding wall 10 by a flange. The pressure switch 1 further comprises a switching mechanism of which the switching state changes if a predetermined pressure ratio between the pressure in the primary pressure chamber 2 and an operating pressure is exceeded.

(6) The temperature of the pressure switch 1 is compensated by the secondary pressure chamber 3 being thermally operatively connected to the primary pressure chamber 2.

(7) Therefore, in the event of a drop in temperature in the primary pressure chamber 2, the temperature in the secondary pressure chamber 3 also drops, which is why a corresponding drop in pressure also occurs in both pressure chambers 2 and 3 due to them being filled with an identical filling medium 8 and 19. Therefore, a temperature-induced drop in temperature in the primary pressure chamber 2 does not cause a change in the switching state of the switching mechanism; therefore, the pressure switch 1 is temperature-compensated.

(8) The basic concept of the present invention is that, by selectively cooling or heating the primary pressure chamber 2 and/or the secondary pressure chamber 3, a temperature gradient is produced between the primary pressure chamber 2 and the secondary pressure chamber 3, which in turn causes a pressure gradient between the primary pressure chamber 2 and the secondary pressure chamber 3. In this case, the pressure gradient produced by the test device 9 has to exceed the pressure ratio that triggers the switching mechanism.

(9) In the embodiment from FIG. 1, the temperature difference is produced by the first temperature-control apparatus 4. Preferably, this is a heating temperature-control apparatus 4, which is also preferably formed by a silicone heating mat. The first temperature-control apparatus 4 may preferably also be formed by a heat accumulator, by any other electrical heating element, by a heating element through which a heating means flows or by a radiating heating element. Preferably, the first temperature-control apparatus 4 has a heating or cooling power of between 10 and 60 W, more preferably of between 15 and 25 W.

(10) The pressure switch 1 largely projects into the primary pressure chamber 2, and therefore the first temperature-control apparatus 4 has to be designed to allow the best possible heat transfer to the part of the pressure switch 1 accessible from the outside. The first temperature-control apparatus 4 is therefore preferably designed to thermally cooperate with the part of the pressure switch 1 outside the primary pressure chamber 2, i.e. a pressure switch housing 11. Preferably, the pressure switch housing 11 forms the surrounding wall 11 of the secondary pressure chamber 3.

(11) The thermal energy is transferred to the secondary pressure chamber 3 and the filling medium 19 contained therein via the pressure switch housing 11. Owing to the thermal inertia of the first primary pressure chamber 2, the first temperature-control apparatus 4 only heats the primary pressure chamber 2 to a considerably lesser extent compared with the secondary pressure chamber 3. A temperature difference between the primary and secondary pressure chambers 2 and 3 can therefore be set, as a result of which a pressure gradient also arises between the two pressure chambers 2 and 3.

(12) In the embodiment shown in FIG. 1, in addition to the first temperature-control apparatus 4 the second temperature-control apparatus 5 is provided, which in this case is preferably formed by a thermal chamber. This is preferably a cooling thermal chamber designed to receive the entire pressurised container 25. In this case, the second temperature-control apparatus 5 almost completely cools the surrounding wall 10 of the primary pressure chamber 2, and therefore the filling medium 8, 19 is also cooled as a result. Therefore, the second temperature-control apparatus 5 can further increase the temperature gradient or can set a temperature gradient that could not be set by the first temperature-control apparatus 4 alone.

(13) Preferably, the pressurised container 25 is oriented such that the pressure switch 1 is arranged in the highest possible position. If this a spherical primary pressure chamber 2, the pressurised container 25 is preferably oriented such that the pressure switch 1 forms the uppermost pole. As can be seen in FIG. 1, due to this orientation of the pressurised container 25 the pressure switch 1 can be completely surrounded by the gas phase 19 of the filling medium, i.e. the liquid phase 8 of the filling medium is not in contact with the pressure switch 1. Because the gas phase 19 is not in contact with the pressure switch 1, it has a thermally insulating effect, such that only a very small proportion of the thermal energy output by the first temperature-control apparatus 4 to the pressure switch 1 is transferred to the filling medium 8 and 19. Therefore, the thermal energy transferred to the pressure switch 1 is largely used to heat the secondary pressure chamber 3, as a result of which a greater temperature gradient between the primary pressure chamber 2 and the secondary pressure chamber 3 arises overall.

(14) Lastly, it may also be expedient to orient the pressurised container 25 in the above-described manner if the primary pressure chamber 2 is filled to the extent that the liquid phase 8 of the filling medium contacts the pressure switch 1 irrespective of the orientation of the pressurised container 25, since here, too, the contact surface between the pressure switch 1 and the liquid phase 8 of the filling medium is decreased, and therefore the transfer of heat is also reduced to a minimum.

(15) Furthermore, in the first embodiment from FIG. 1, a first sensor apparatus 12 is provided which is preferably arranged at a contact point between the first temperature-control apparatus 4 and the pressure switch 1. More preferably, the sensor apparatus is also arranged on the flange of the pressure switch 1, which is used to attach the pressure switch 1 to the surrounding wall 10.

(16) If a first temperature-control apparatus 4 is formed by a silicone heating mat, the first sensor apparatus 12 may preferably be integrated into the silicone heating mat. By means of the first sensor apparatus 12, which is preferably formed by a temperature-measuring apparatus, e.g. by a PT100 sensor, the surface temperature of the pressure switch housing 11 can be monitored and thus the pressure switch 1 can be prevented from being thermally overloaded.

(17) Alternatively or additionally, a second sensor apparatus 13 can also be provided to monitor the temperature of the primary pressure chamber 2. Preferably, the second sensor apparatus 13 is arranged on the surrounding wall 10 of the primary pressure chamber 2, more preferably at a point on the primary pressure chamber 2 opposite the pressure switch 1. By means of the two measuring points of the first and second sensor apparatus 12 and 13, the temperature gradient and thus also the pressure gradient between the primary pressure chamber 2 and the secondary pressure chamber 3 can be approximately determined.

(18) Furthermore, a detection apparatus 15 for determining the masses and/or volumes of the liquid and gas phases 8 and 19 of the filling medium can be provided. The values determined by the detection apparatus 15 can be used together with a thermodynamic fluid model in order to calculate the nominal state of the primary and secondary pressure chamber 2 and 3. In this way, more precise statements can be made on the thermodynamic conditions at the triggering time of the switching mechanism, as a result of which the functionality of the pressure switch 1 can be assessed more reliably as a whole. In this embodiment, the detection apparatus 15 is preferably formed by a mass-determination apparatus, which is only shown schematically in FIG. 1. Any other arrangement of the detection apparatus 15 is likewise conceivable.

(19) In addition, a heating controller 16 is provided, which is connected to the first temperature-control apparatus 4 by a connection line 20. The heating controller 16 is thus used to set the heating power.

(20) In addition, a continuity tester 14 is preferably provided, which is electrically connected to the pressure switch 1 by a connection line 21 and can detect the switching state that the switching mechanism is in. Preferably, the continuity tester 14 is formed by a multimeter.

(21) Preferably, a control apparatus 18 is additionally provided, which is preferably connected to the heating controller 16, the continuity tester 14 and/or the detection apparatus 15 by connection lines 22, 23 and 24 by way of signals. In this case, the control apparatus 18 is preferably designed to carry out the test sequence automatically. The control apparatus 18 may for example give the heating controller 16 the signal to activate the first temperature-control apparatus 4 for a heating process. This preferably takes place until the continuity tester 14 has detected a change in the switching state of the switching mechanism and has made this information available to the control apparatus 18 by means of the connection line 23. The additional heating by the first temperature-control apparatus 4 is therefore stopped, such that the secondary pressure chamber 3 cools and, as a result of equalisation of the temperatures in the primary and secondary pressure chamber 2 and 3, the original switching state of the switching mechanism is re-established. Therefore, a switching hysteresis of the switching mechanism can also be determined, i.e. at which point in time or at which pressure gradient the switching mechanism is switched from a first switching state into a second switching state and back again.

(22) Preferably, the first and/or second sensor apparatus 12 and/or 13 can be connected to the control apparatus 18 by way of signals. The temperature can thus be monitored during the entire test sequence in order to prevent thermal overloading at the pressurised container 25.

(23) Preferably, the information from the detection apparatus 15 can also be processed, for example in order to obtain more precise statements on the thermodynamic conditions during the change in the switching states in combination with the temperature values from the first and second sensor apparatus 12 and 13. These values may for example be stored on a data carrier or another storage medium that is specific to the pressurised container 25 to be tested in each case, so that it is also possible to archive the test results.

(24) If a control apparatus 18 is omitted, the first and/or second temperature-control apparatus 4 and/or 5 can also be deactivated manually or automatically after a preset time has elapsed.

(25) The control apparatus 18 shown in FIG. 1 may alternatively also assume the function of the heating controller 16 and/or the continuity tester 14.

(26) FIG. 2 shows a second embodiment of the invention, which has a similar structure to the first embodiment from FIG. 1. The major difference between these embodiments is that the second temperature-control apparatus 5 is not formed by a thermal chamber but preferably by a cooling element in direct contact with the surrounding wall 10 of the primary pressure chamber 2.

(27) Preferably, this is a planar cooling element which is or can be adapted to the contour of the surrounding wall 10, has a high coefficient of thermal conduction, and is made of copper, for example. Alternatively, direct liquid cooling by means of a cooling circuit or direct cooling by liquid nitrogen are also possible.

(28) The contact surface between the second temperature-control apparatus 5 and the surrounding wall 10 may be a different size depending on the required temperature gradient. Therefore, for a spherical geometry of the pressurised container, for example only the lower pole, the lower half or the entire surrounding wall 10 can be cooled. The thermal conductivity may preferably be improved by a thermally conductive mass, and this also applies to the contact surface between the first temperature-control apparatus 4 and the pressure switch 1.

(29) Furthermore, it can be seen from FIG. 2 that the part of the surrounding wall 10 that is not surrounded by the second temperature-control apparatus 5 is preferably surrounded by a thermal insulation apparatus 6. The cooling of the primary pressure chamber 2 carried out by the second temperature-control apparatus 5 can thus be prevented from being reduced by the ambient heat energy being absorbed through the surrounding wall 10. Preferably, the thermal insulation apparatus 6 can additionally also surround the part of the pressure switch 1 projecting from the primary pressure chamber 2.

(30) Lastly, an active cooling or heating element 7 can be provided that is designed to reduce or compensate for the undesired thermal effect of the first temperature-control apparatus 4 on the primary pressure chamber 2. If the first temperature-control apparatus 4 is designed as a thermal element, the active cooling or heating element 7 is designed as a cooling element, and vice versa. The cooling element is preferably liquid-cooled.

(31) For the best possible effect, the active cooling or heating element 7 is arranged as close as possible to the first temperature-control apparatus 4, i.e. at a distance of less than 100 mm from the flange of the pressure switch 1, more preferably of less than 50 mm and yet more preferably of less than 20 mm.

(32) Furthermore, it has proven advantageous for the active cooling or heating element 7 to annularly surround the first temperature-control apparatus 4, such that the unimpeded transfer of heat into the remote or lower region of the surrounding wall 10 of the primary pressure chamber 2 can be prevented.

(33) In practice, it has been shown that by means of the combination of the thermal insulation apparatus 6 with the active cooling element 7, thermal decoupling of the heating brought about by the first temperature-control apparatus 4 from the cooling produced by the second temperature-control apparatus 5 can be achieved, and this results in a greater capacity of the test device 9 for the purpose of a greater temperature gradient.

(34) Another difference compared with the first embodiment in FIG. 1 is that a power-measuring apparatus 17 is provided, which is used to monitor the heating or cooling power preferably of the first temperature-control apparatus 4. Alternatively or additionally, the power-measuring apparatus 17 can also be associated with the second temperature-control apparatus 5.

(35) Lastly, there is also a difference in the detection apparatus 15, which is formed by an ultrasonic measuring apparatus in the second embodiment.

(36) Any combination of the embodiments shown in FIG. 1 and FIG. 2 should be included in the disclosure of this application.

(37) In addition, the disclosure of this application is not limited to the embodiments which are described in the preceding examples from FIG. 1 and FIG. 2 and in which the first temperature-control apparatus 4 is designed as a heating element and the second temperature-control apparatus 5 is designed as a cooling element. It is also possible to produce a temperature gradient in the reverse manner, i.e. by the first temperature-control apparatus 4 being a cooling element and the second temperature-control apparatus 5 being a thermal element.

(38) Furthermore, modifications to the embodiments shown in FIG. 1 and FIG. 2 in which only a first or only a second temperature-control apparatus 4 or 5 is provided should expressly be included in the disclosure of this application.

Embodiment 1

(39) Method for testing a temperature-compensated, pressure-gradient-controlled pressure switch (1), which is pneumatically associated with a primary pressure chamber (2) and comprises a secondary pressure chamber (3) for temperature compensation,

(40) characterised in that,

(41) by using at least one temperature-control apparatus (4, 5) between the primary pressure chamber (2) and the secondary pressure chamber (3), a temperature gradient is set which is sufficiently great to produce a pressure gradient between the primary pressure chamber (2) and the secondary pressure chamber (3) that corresponds at least to the triggering pressure gradient of the pressure switch (1).

Embodiment 2

(42) Method according to Embodiment 1, characterised in that the secondary pressure chamber (3) is heated or cooled by the first temperature-control apparatus (4).

Embodiment 3

(43) Method according to Embodiment 2, characterised in that an active cooling or heating element (7) is thermally connected to the primary pressure chamber (2) such that the thermal effects of the first temperature-control apparatus (4) on the primary pressure chamber (2) are compensated for at least in part.

Embodiment 4

(44) Method according to any of the preceding Embodiments, characterised in that the primary pressure chamber (2) is cooled or heated by the second temperature-control apparatus (5).

Embodiment 5

(45) Method according to claim 4 with reference to any of Embodiments 2 to 3, characterised in that the secondary pressure chamber (3) is heated by the first temperature-control apparatus (4) and the primary pressure chamber (2) is simultaneously cooled by the second temperature-control apparatus (5).

Embodiment 6

(46) Method according to any of the preceding Embodiments, characterised in that the primary pressure chamber (2) is oriented such that a liquid phase of a filling medium (8) contained therein has as small as possible a contact surface with the pressure switch (1).

Embodiment 7

(47) Test device (9) for testing a temperature-compensated, pressure-gradient-controlled pressure switch (1), which is pneumatically associated with a primary pressure chamber (2) and comprises a secondary pressure chamber (3) for temperature compensation, characterised in that a temperature-control apparatus (4, 5) is provided by means of which a temperature gradient between the primary pressure chamber (2) and the secondary pressure chamber (3) can be set, and the pressure switch (1) can be actuated by a pressure gradient caused by the temperature gradient.

Embodiment 8

(48) Test device (9) according to Embodiment 7, characterised in that the test device (9) is designed to set a temperature difference of at least 10 K between the primary pressure chamber (2) and the secondary pressure chamber (3).

Embodiment 9

(49) Test device (9) according to either Embodiment 7 or Embodiment 8, characterised in that a first temperature-control apparatus (4) is designed to cool or heat a surrounding wall (11) of the secondary pressure chamber (3) in a targeted manner.

Embodiment 10

(50) Test device (9) according to Embodiment 9, characterised in that the first temperature-control apparatus (4) is formed by a silicone heating mat.

Embodiment 11

(51) Test device (9) according to any of Embodiments 7 to 10, characterised in that a second temperature-control apparatus (5) is designed to cool or heat a surrounding wall (10) of the primary pressure chamber (2) in a targeted manner.

Embodiment 12

(52) Test device (9) according to any of Embodiments 7 to 11, characterised in that a thermal insulation apparatus (6) surrounds the outer surface of the surrounding wall (10).

Embodiment 13

(53) Test device (9) according to any of Embodiments 7 to 12, characterised in that a first sensor apparatus (12) is provided to determine the temperature of a surrounding wall (11) of the secondary pressure chamber (3) and/or a second sensor apparatus (13) is provided to determine the temperature of a surrounding wall (10) of the primary pressure chamber (2).

Embodiment 14

(54) Test device (9) according to any of Embodiments 7 to 13, characterised in that a detection apparatus (15) is provided to determine the fill level of the primary pressure chamber (2).

Embodiment 15

(55) Test device (9) according to any of Embodiments 7 to 14, characterised in that a continuity tester (14) is provided to determine the switching state of the pressure switch (1).