Gas probe for sampling gas molecules from a fluid and a system comprising the gas probe

1. A gas probe for sampling gas molecules from a fluid, said gas probe comprising;

a probe housing with an orifice for entrance of said gas sample molecules from said fluid into an interior of said probe housing, and said gas probe being adapted to be arranged such that said interior of said probe housing is arranged in gas communication with a test gas sensor configured to detect test gas molecules among said gas sample molecules,

a protecting member comprising a stack of layers, whereby said stack is arranged in said probe housing in a flow path for gas sample molecules from said orifice and further into said probe housing such that gas sample molecules are required to pass through all layers of said stack in order to pass further into said probe housing and in order to reach said test gas sensor, whereby gas sample molecules pass through said stack in a gas sample flow, and whereby said stack comprises, seen in a direction of said gas sample flow through said stack, at least a first membrane layer, a first spacer layer, a first filter layer and a second spacer layer,

wherein said probe housing comprises an inlet for introducing blocking gas molecules into said second spacer layer and an outlet for discharging blocking gas molecules out of said first spacer layer, whereby said blocking gas molecules are required to pass through said first filter layer in a blocking gas flow being directed in a direction opposite to the direction of said gas sample flow in order to reach said outlet, and

wherein said gas probe is connectable to a control unit for controlling the flow of blocking gas molecules into said second spacer layer through said inlet so as to control said blocking gas flow through said first filter layer in order to control said gas sample flow through said first filter layer.

2. The gas probe according to claim 1 , wherein said gas probe comprises said control unit.

3. The gas probe according to claim 1 , wherein said stack further comprises a second filter layer interposed between said first membrane layer and said first spacer layer, whereby said second filter layer is arranged after said first membrane layer but before said first spacer layer seen in the direction of said gas sample flow through said stack.

4. The gas probe according to claim 1 , wherein said stack further comprises a second filter layer arranged before said first membrane layer seen in the direction of said gas sample flow through said stack.

5. The gas probe according to claim 1 , wherein said stack further comprises a third filter layer arranged after said second spacer layer seen in the direction of said gas sample flow through said stack and a third spacer layer arranged after said third filter layer seen in the direction of said gas sample flow through said stack.

6. The gas probe according to claim 5 , wherein said stack further comprises a second membrane layer interposed between said third filter layer and said third spacer layer.

7. The gas probe according to claim 1 , wherein said stack further comprises a fourth filter layer and a fourth spacer layer interposed between said first spacer layer and said first filter layer, whereby said fourth filter layer is arranged before said fourth spacer layer seen in the direction of said gas sample flow through said stack.

8. The gas probe according to claim 1 , wherein said test gas is selected from the group consisting of: hydrogen, helium, carbon dioxide, sulphur hexafluoride, and a hydrocarbon.

9. A test gas detection system, comprising:

a gas probe comprising a probe housing with an orifice for entrance of said gas sample molecules from said fluid into an interior of said probe housing, and said gas probe being adapted to be arranged such that said interior of said probe housing is arranged in gas communication with a test gas sensor configured to detect test gas molecules among said gas sample molecules; a protecting member comprising a stack of layers, whereby said stack is arranged in said probe housing in a flow path for gas sample molecules from said orifice and further into said probe housing such that gas sample molecules are required to pass through all layers of said stack in order to pass further into said probe housing and in order to reach said test gas sensor, whereby gas sample molecules pass through said stack in a gas sample flow, and whereby said stack comprises, seen in a direction of said gas sample flow through said stack, at least a first membrane layer, a first spacer layer, a first filter layer and a second spacer layer; wherein said probe housing comprises an inlet for introducing blocking gas molecules into said second spacer layer and an outlet for discharging blocking gas molecules out of said first spacer layer, whereby said blocking gas molecules are required to pass through said first filter layer in a blocking gas flow being directed in a direction opposite to the direction of said gas sample flow in order to reach said outlet; and wherein said gas probe is connectable to a control unit for controlling the flow of blocking gas molecules into said second spacer layer through said inlet so as to control said blocking gas flow through said first filter layer in order to control said gas sample flow through said first filter layer; and

a test gas sensor.

10. The test gas detection system according to claim 9 , wherein said test gas sensor is arranged in the interior of said probe housing of said gas probe.

11. The test gas detection system according to claim 9 , wherein said test gas sensor is arranged in a separate sensor unit being connectable to the interior of said probe housing of said gas probe.

12. The test gas detection system according to claim 9 , further comprising:

at least one device selected from the group consisting of: a blocking gas source, a blocking gas pump and a measurement unit.

13. A leak testing system, comprising:

a test gas detection system a gas probe comprising a probe housing with an orifice for entrance of said gas sample molecules from said fluid into an interior of said probe housing, and said gas probe being adapted to be arranged such that said interior of said probe housing is arranged in gas communication with a test gas sensor configured to detect test gas molecules among said gas sample molecules; a protecting member comprising a stack of layers, whereby said stack is arranged in said probe housing in a flow path for gas sample molecules from said orifice and further into said probe housing such that gas sample molecules are required to pass through all layers of said stack in order to pass further into said probe housing and in order to reach said test gas sensor, whereby gas sample molecules pass through said stack in a gas sample flow, and whereby said stack comprises, seen in a direction of said gas sample flow through said stack, at least a first membrane layer, a first spacer layer, a first filter layer and a second spacer layer; wherein said probe housing comprises an inlet for introducing blocking gas molecules into said second spacer layer and an outlet for discharging blocking gas molecules out of said first spacer layer, whereby said blocking gas molecules are required to pass through said first filter layer in a blocking gas flow being directed in a direction opposite to the direction of said gas sample flow in order to reach said outlet; and wherein said gas probe is connectable to a control unit for controlling the flow of blocking gas molecules into said second spacer layer through said inlet so as to control said blocking gas flow through said first filter layer in order to control said gas sample flow through said first filter layer; and a test gas sensor; and

at least one device selected from the group consisting of: a sealable test chamber arranged to receive a test object, a flange for connection of said gas probe to said test chamber, a tracer gas source, a tracer gas control unit, a tracer gas pressure regulator, a vacuum pump, a fixture for said test object and a fixture control unit.