Device and method for distinguishing a test gas escaping from a leak from an interfering gas

Patent metadata

Field	Value
Publication number	US-RE50099-E
Application number	US-201818073708-A
Country	US
Kind code	E1
Filing date	Sep 28, 2018
Priority date	Sep 29, 2017
Publication date	Aug 27, 2024
Grant date	Aug 27, 2024

Abstract

A method for distinguishing a test gas escaping from a leak in a test object ( 21 ) from an interfering gas in the environment of the test object ( 21 ) during sniffing leak detection, having the steps: suctioning gas from the environment of the test object ( 21 ) in the region of the outer surface of the test object by means of a sniffing tip, which has a suction opening ( 14 ), which is connected, for gas conduction, to a sensor ( 18 ), which is designed to determine the test gas partial pressure of the test gas in the suctioned gas flow; varying, with periodic repetition, the flow intensity of the suctioned gas flow; setting a total pressure of the suctioned gas at the sensor ( 18 ) of at least 80 percent of the total pressure of the gas in the atmosphere ( 23 ) surrounding the test object ( 21 ); avoiding fluctuations of the total pressure of the suctioned gas at the sensor ( 18 ) of more than 10 percent; measuring the test gas partial pressure of test gas contained in the suctioned gas flow by means of the sensor ( 18 ); indicating that the test object ( 21 ) has a leak if the measured test gas partial pressure has a varying component, the average amplitude of which lies above a threshold value and which follows the variation of the suctioned gas flow.

First claim

The invention claimed is:

1. A method for distinguishing a test gas escaping from a leak in a test object from an interfering gas in the environment of the test object during sniffing leak detection, having the steps:
suctioning gas from the environment of the test object in the region of the outer surface of the test object by means of a sniffing tip, which sniffing tip has a suction opening, which suction opening is connected, for gas conduction, to a sensor, which sensor is designed to determine the test gas partial pressure of the test gas in the suctioned gas flow;
varying, with periodic repetition, the flow intensity of the suctioned gas flow;
setting a total pressure of the suctioned gas at the sensor of at least 80 percent of the a total pressure of the gas in the atmosphere surrounding the test object;
avoiding fluctuations of the total pressure of the suctioned gas at the sensor of more than 10 percent;
measuring the test gas partial pressure of test gas contained in the suctioned gas flow by means of the sensor; and
indicating that the test object has a leak if the measured test gas partial pressure has a varying component, the mean amplitude of which is greater than a threshold value and which follows the variation of the suctioned gas flow.

2. The method according to claim 1 , characterized in that an indication is provided further comprising providing an indication that there is no leak if the measured test gas component partial pressure does not have a varying component exceeding the threshold value.

3. The method according to claim 1 , characterized in that the varying, periodically repeated, of the flow intensity of the suctioned gas occurs in the form of a modulation with a modulation frequency in the range of 1 Hz to 20 Hz.

4. The method according to claim 1 , characterized in that the total pressure of the suctioned gas flow at the sensor is set to a value in the range between 90 percent and 110 percent of the total pressure of the gas in the atmosphere surrounding the test objectatmosphere.

5. The method according to claim 1 , characterized in that further comprising demodulating a modulated flow intensity signal of the suctioned gas flow is demodulated according to the principle of a lock-in amplifier with a defined frequency reference and phase reference for modulating the suctioned gas flow.

6. The method according to claim 1 , characterized in that in addition there is further comprising performing a comparison measurement of the test gas partial pressure without varying the flow intensity of the suctioned gas flow for comparison purposes.

7. The method according to claim 1 , characterized in that the total pressure of the gas in the atmosphere surrounding the test object in the region of the sniffer is atmospheric pressure in the range of approx. 900 mbar to approx. 1100 mbar.

8. A sniffing leak detector having:
a sniffer having a suction opening;
a gas pump;
a sensor determining the a test gas partial pressure of the a test gas to be detected;
a gas line path connecting the suction opening, the sensor, and the gas pump;
a control device designed to repeatedly vary the flow intensity of the a suctioned gas flow, to set the a total pressure of the suctioned gas flow at the sensor to at least about 80 percent of the a total pressure of the gas in the an atmosphere surrounding the test object, and to avoid fluctuations in the total pressure of the gas at the sensor of more than 10 percent; and,
an evaluation device designed configured to determine whether the test gas partial pressure of test gas contained in the suctioned gas flow has a varying component, the mean amplitude of which is greater than a threshold value and which follows wherein a frequency of the varying component of the test gas partial pressure corresponds to a frequency of the variation of the suctioned gas flow, and wherein a phase of the varying component corresponds to a phase of the flow intensity of the suctioned gas flow.

9. The sniffing leak detector according to claim 8 , characterized in that the sensor is arranged downstream of the gas pump.

10. The sniffing leak detector according to claim 8 , characterized in that the gas line path has comprises a throttle positioned between the suction opening and the sensor.

11. The sniffing leak detector according to claim 10 , characterized in that the throttle is a capillary tube having a length in the range of approx. 2 cm to approx. 100 cm and having a diameter of a maximum of approx. 5 mm.

Assignees

• Inficon Gmbh

Inventors

• Wetzig Daniel

Classifications

• G01M3/22 Primary

  for pipes, cables or tubes; for pipe joints or seals; for valves; {for welds; for containers, e.g. radiators} · CPC title

• G01M3/20

  using special tracer materials, e.g. dye, fluorescent material, radioactive material · CPC title

• G01M3/205

  Accessories or associated equipment; Pump constructions · CPC title

• G01M3/222 Primary

  for tubes · CPC title