FILM CHAMBER COMPRISING A CARRIER GAS SUPPLY, AND METHOD FOR LEAK TESTING

Abstract

The invention relates to a film chamber (10) for testing the sealing tightness of a test specimen containing a test fluid, the film chamber comprising: at least one vacuum connection (20) which can be connected to a vacuum pump (32) and a gas detector (36); at least one flexible wall region (14) that defines a film chamber volume; and a frame (12) that surrounds the flexible wall region (14) on the outside in order to seal the film chamber volume. The film chamber is characterized in that: the vacuum connection (20) is located in a region arranged centrally with respect to the frame (12) and is radially outwardly surrounded by the frame (12); and at least one gas inlet (22, 30) for supplying a carrier gas is located in the region of the outer frame in such a way that the carrier gas flows through the gas inlet through the film chamber volume along the flexible wall region (14) radially from the outside inwardly to the vacuum connection (20).

Claims

1.-14. (canceled)

15. A film chamber for leak testing a test specimen containing a test fluid, wherein the film chamber comprises: at least one vacuum port connectable to a vacuum pump and to a gas detector; at least one flexible wall portion defining a film chamber volume; and a frame surrounding the flexible wall portion on the outside for closing the film chamber volume, wherein: the at least one vacuum port is arranged in an area located centrally with respect to the frame and surrounded radially on the outside by the frame; and at least one gas inlet for the supply of a carrier gas is arranged in the area of the outer frame such that the carrier gas flows through the gas inlet through the film chamber volume along the flexible wall portion radially from the outside inward to the vacuum port.

16. The film chamber according to claim 15, wherein the frame is designed to extend annularly around the flexible wall portion and delimits the flexible wall portion.

17. The film chamber according to claim 16, wherein the gas conductance value in the film chamber volume in the region of the frame is greater in the circumferential direction than the gas conductance value in the radial direction from the gas inlet to the vacuum port.

18. The film chamber according to claim 15, wherein the vacuum port or the gas inlet is arranged concentrically with respect to the frame.

19. The film chamber according to claim 15, wherein the walls of the film chamber are designed to be entirely flexible and are clamped in the frame.

20. The film chamber according to claim 15, wherein the gas inlet or the vacuum port is formed in the frame or adjacent to the frame.

21. The film chamber according to claim 15, wherein the frame comprises a plurality, preferably two gas inlets or vacuum ports.

22. The film chamber according to claim 21, wherein the gas inlets or vacuum ports are arranged distributed evenly along the circumference of the frame at regular distances from each other.

23. The film chamber according to claim 15, wherein two vacuum ports or gas inlets are formed on opposing sides of the film chamber volume.

24. The film chamber according to claim 15, wherein the frame has two opposing inner frame surfaces adjacent to the film chamber volume, and the two films have opposing inner film surfaces adjacent to the film chamber volume, the distance between the inner frame surfaces being greater than the distance between the inner film surfaces in the evacuated state of the film chamber when no test specimen is contained in the film chamber.

25. The film chamber according to claim 15, wherein the flexible wall portion comprises a material that does not absorb test fluid and/or carrier gas, in particular silicone, butyl rubber or EPDM.

26. A method for leak testing a test specimen containing a test fluid using a film chamber according to claim 15, the method comprising the steps of: introducing the test specimen into the film chamber; evacuating the film chamber by means of a vacuum pump connected to the vacuum port; supplying a carrier gas to the film chamber via the gas inlet; drawing a gas mixture, which is formed by the carrier gas and a test fluid escaping through a leak in the test specimen, through the vacuum port and supplying the drawn gas mixture to a gas detector; analyzing the gas mixture for the presence of test fluid using the gas detector; wherein the carrier gas flows through the gas inlet through the film chamber volume along a flexible wall portion radially from an outside inward or from an inside outward to the vacuum port.

27. The method according to claim 26, wherein after flowing into the film chamber volume through the gas inlet or before flowing out of the film chamber volume through the vacuum port, the carrier gas flows with a greater gas conductance value in the circumferential direction than in the radial direction in the direction towards the vacuum port or the gas inlet.

28. A film chamber for leak testing a test specimen containing a test fluid, wherein the film chamber comprises: at least one vacuum port connectable to a vacuum pump and to a gas detector; at least one flexible wall portion defining a film chamber volume; and a frame surrounding the flexible wall portion on the outside for closing the film chamber volume; wherein: at least one gas inlet for the supply of a carrier gas is arranged in an area located centrally with respect to the frame and surrounded radially on the outside by the frame; and the at least one vacuum port is arranged in the area of the outer frame such that the carrier gas flows through the gas inlet through the film chamber volume along the flexible wall portion radially from the inside outward to the vacuum port.

29. The film chamber according to claim 28, wherein the frame is designed to extend annularly around the flexible wall portion and delimits the flexible wall portion.

30. The film chamber according to claim 29, wherein the gas conductance value in the film chamber volume in the region of the frame is greater in the circumferential direction than the gas conductance value in the radial direction from the gas inlet to the vacuum port.

31. The film chamber according to claim 28, wherein the vacuum port or the gas inlet is arranged concentrically with respect to the frame.

32. The film chamber according to claim 28, wherein the walls of the film chamber are designed to be entirely flexible and are clamped in the frame.

33. The film chamber according to claim 28, wherein the gas inlet or the vacuum port is formed in the frame or adjacent to the frame.

34. The film chamber according to claim 28, wherein the frame comprises a plurality, preferably two gas inlets or vacuum ports.

35. The film chamber according to claim 34, wherein the gas inlets or vacuum ports are arranged distributed evenly along the circumference of the frame at regular distances from each other.

36. The film chamber according to claim 28, wherein two vacuum ports or gas inlets are formed on opposing sides of the film chamber volume.

37. The film chamber according to claim 28, wherein the frame has two opposing inner frame surfaces adjacent to the film chamber volume, and the two films have opposing inner film surfaces adjacent to the film chamber volume, the distance between the inner frame surfaces being greater than the distance between the inner film surfaces in the evacuated state of the film chamber when no test specimen is contained in the film chamber.

38. The film chamber according to claim 28, wherein the flexible wall portion comprises a material that does not absorb test fluid and/or carrier gas, in particular silicone, butyl rubber or EPDM.

39. A method for leak testing a test specimen containing a test fluid using a film chamber according to claim 28, the method comprising the steps of: introducing the test specimen into the film chamber; evacuating the film chamber by means of a vacuum pump connected to the vacuum port; supplying a carrier gas to the film chamber via the gas inlet; drawing a gas mixture, which is formed by the carrier gas and a test fluid escaping through a leak in the test specimen, through the vacuum port and supplying the drawn gas mixture to a gas detector; analyzing the gas mixture for the presence of test fluid using the gas detector; wherein the carrier gas flows through the gas inlet through the film chamber volume along a flexible wall portion radially from an outside inward or from an inside outward to the vacuum port.

40. The method according to claim 39, wherein after flowing into the film chamber volume through the gas inlet or before flowing out of the film chamber volume through the vacuum port, the carrier gas flows with a greater gas conductance value in the circumferential direction than in the radial direction in the direction towards the vacuum port or the gas inlet.

Description

[0022] FIG. 1 is a schematic illustration of a first embodiment,

[0023] FIG. 2 is a schematic view of a second embodiment and

[0024] FIG. 3 is a perspective view of a third embodiment.

[0025] The film chamber 10 of the first two embodiments comprises an annular circumferential frame 12. In the third embodiment, the frame 12 is also annularly circumferential, while not being annular in shape, but almost rectangular with rounded corners. Other annular geometries of the frame 12 are conceivable.

[0026] The frame 12 can be of a two-part design formed by two complementarily shaped frame parts, each frame part 12a, 12b supporting a respective film chamber wall 14. The two frame parts 12, 12b are each connected to one another in a gas-tight manner by means of two seals 16, 18 which are also shaped as circular rings, as illustrated in FIG. 2.

[0027] Each of the two films 14 is clamped in one of the two frame parts 12a, 12b and at least one of the films is provided with a vacuum port 20 arranged concentrically centered with respect to the circumferential frame 12. The frame 12 has a gas inlet 22 for the supply of carrier gas through the frame into the interior of the film chamber. In the embodiment of FIG. 1, a gas inlet 22, 30 is provided. In the embodiments of FIGS. 2 and 3, two gas inlets 22, 30 for the carrier gas are formed on opposing sides of the frame 12. In FIG. 1, a flushing gas source and a carrier gas source are connected to the gas inlet 22 via valves V1, V2. The frame further comprises another gas port 24. The gap 26 formed between the two seals 16, 18 can be evacuated via the gas port 24 by means of a vacuum pump 28 connected to the port 24. In the embodiment of FIG. 1, the vacuum pump 28 is connected to the gas port 24 via a valve V3.

[0028] The two frame parts 12a, 12b each have inner frame surfaces 13 on their sides adjacent to the film chamber volume and facing each other. The inner frame surfaces 13 of the two frame parts 12a, 12b are arranged at a distance d.sub.2 from one another. This distance d.sub.2 remains the same in the closed state of the frame and in the closed state of the film chamber and also in the evacuated state of the film chamber.

[0029] Both films 14 respectively comprise an inner film surface 15 on their side facing the film chamber volume. In the closed state of the film chamber, which is illustrated in FIG. 2, a distance d.sub.1 remains between the two inner film surfaces 15 both in the evacuated state and the non-evacuated state. Only, when a test specimen is contained between the films 14 which is bounded by the films 14, the films 14 can yield and have a greater distance in the area of the test specimen. The distance d.sub.2 is greater than the distance d.sub.1, so that the carrier gas flowing into the film chamber volume through the gas inlets 22, 30 first spreads, in particular in the evacuated state of the vacuum pump, in the circumferential direction between the two frame parts 12a, 12b due to the greater distance d.sub.2 before, due to the smaller distance d.sub.1, it flows radially inwards from the outside from all radial directions towards the central vacuum ports 20. This results in a gas flow of the carrier gas from the outside to the inside, which is evenly distributed over the circumference.

[0030] As illustrated in FIG. 1, a vacuum pump 32 is connected to the vacuum port 20. In the embodiment of FIG. 1, the vacuum pump 32 is connected to the vacuum port 20 via a valves V4, V6. A gas detector 36 is connected to the gas conduction path 34 that connects the vacuum pump 32 to the vacuum port 20, by which detector the evacuated gas from the film chamber 10 can be analyzed for the presence of test fluid. Here, the gas detector 36 is connected to a detection gas conduction path 38 having two ends which are connected to the gas conduction path 34 via a valve V7, V8, respectively.

[0031] This allows the film chamber volume to be evacuated with the valves V4 and V6 open while the vacuum pump 32 is running, after the test specimen has been introduced. As soon as a sufficient vacuum is reached, the valve V5 can be closed, and the film chamber volume is supplied with a throttled, continuous carrier gas flow via the gas inlet 22 with the valve V2 open, which, in the flow chamber volume, flows radially from the outside to the inside along the inner side of the film chamber walls 14 in the direction towards the vacuum port 20. The valve V6 is closed and the valves V7 and V8 are opened, so that the gas mixture drawn from the film chamber volume is supplied to the gas detector 36 via the open valves V4 and V7 and eventually reaches the vacuum pump 32 via the open valve V8 and from there escapes into the ambient atmosphere.

[0032] After the leak test is completed, with the valve V2 closed and the valve V1 open, a flashing gas flow can be supplied to the film chamber volume via the gas inlet 22 to flush the same. Here, the flushing gas supply via the valve V1 is not or at least less strongly throttled than the carrier gas supply viy the opened valve V2.

[0033] With the valve V3 open and the vacuum pump 28 running, the gap of the frame, which is also referred to as the chamber ring gap, between the two seals 16, 18 can be evacuated to thereby press the two frame parts 12a, 12b against each other and to thus close the film chamber 12.

[0034] Advantageously, the carrier gas flow flows radially symmetrically from the outer chamber frame inwards through the space between the test chamber walls to the vacuum port in the centre of the wall or the film. This enables leakage gas escaping at one point of the test specimen to be detected with the same sensitivity and at the same rate (response time).

[0035] The uniformity of the gas flow is substantially influenced by the conductance value along the film space and the pressure difference between the inlet (at the respective transition from the chamber ring to the film space) and the vacuum port in the centre of the film.

[0036] To his end, the pressure in the chamber ring gap should be homogeneous. For this purpose, the gas conductance value in the circumferential direction along the chamber ring gap from the point of the carrier gas inlet 22 to the point in the chamber ring gap farthest away from the gas inlet 22 must be greater by at least a factor 10 that the gas conduction value in the radial direction along the space (film chamber volume) formed by the film chamber walls from the chamber ring gap to the centre of the respective film chamber wall.

[0037] The embodiments regarding the second variant of the invention correspond essentially to the ones illustrated in FIGS. 1-3, except for the difference that vacuum ports and gas inlets are interchanged.