CA2121476C - Gas leak sensor system - Google Patents
Gas leak sensor system Download PDFInfo
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- CA2121476C CA2121476C CA002121476A CA2121476A CA2121476C CA 2121476 C CA2121476 C CA 2121476C CA 002121476 A CA002121476 A CA 002121476A CA 2121476 A CA2121476 A CA 2121476A CA 2121476 C CA2121476 C CA 2121476C
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- Canada
- Prior art keywords
- gas
- sensor
- sensor system
- set forth
- gas leak
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M3/00—Investigating fluid-tightness of structures
- G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
- G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
- G01M3/20—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material
Abstract
A gas leak sensor system detects the presence of gas leaking into any one of a plurality of test spaces for example, refrigeration gas into a refrigeration case. A plurality of tubes extend from each of the test spaces to a sensor location whereat a selector valve is connected to each tube. A controller actuates the selector valves to select tubes in a particular order and a vacuum source draws air and any leaking gas through a selected tube and through a gas sensor to activate an alarm. The gas sensor is purged at least each time a leaking gas has been sensed. The foregoing Abstract is merely a resume of general applications, it is not a complete discussion of all principles of operation or applications, and is not to be construed as a limitation on the scope of the claimed subject matter.
Description
3 Supermarkets and warehouses have many isolated refrigeration 4 coils were potential leaks can occur. Individual sensing devices at each location would be cost prohibitive. U.S. Patent 3,357,257 6 discloses the concept of a plurality of test spaces with tubing 7 leading from the testing spaces through valves to a single gas 8 sensor but no means for purging the system is disclosed.
A gas leak sensor system detects the presence of a gas leaking 11 into any one of a plurality of test spaces and includes a plurality 12 of tubes extending from each of the test spaces to a sensor 13 location. Selector valve means are connected to each tube and a 14 gas sensor has an alarm. Control means is connected to actuate the selector valve means to select tubes in a particular order, means 16 is connected to the selector valve means to draw air and any 17 leaking gas through the selected tube and through the gas sensor, 18 and means to purge said gas sensor at least when leaking gas has 19 been sensed. Accordingly, a gas leak sensor system is disclosed which can sense a plurality of test spaces with a means to purge 21 the gas sensor after the sensing of leaking gas.
22 Another object of an aspect of the invention is to provide a 23 purging means which uses outside air from a location separate from 24 the discharge from said gas sensor.
1 In accordance with one aspect of the present invention, there 2 is provided a gas leak sensor system for detecting the presence of 3 gas leaking into any of a plurality of test spaces, comprising, in 4 combination:
a plurality of tubes extending from each of the test 6 spaces to a sensor location;
7 selector valve means connected to each tube;
8 a gas sensor having an alarm;
9 control means to actuate said selector valve means to select tubes in a particular order;
11 means connected to the selector valve means to draw air 12 and any leaking gas through the selected tube and through the gas 13 sensor;
14 means to purge said gas sensor at least when leaking as has been sensed; and I6 said purging means having a purging gas inlet remote from 17 said test spaces.
18 Other objects and a fuller understanding of the invention may 19 be had by referring to the following description and claims, taken in conjunction with the accompanying drawings.
22 FIG. 1 is a schematic diagram of the gas leak sensor system 23 according to the invention;
24 FIG. 2 is an enlarged view of the termination of an individual tube at a test space;
2a 1 FIG. 3 is a plan view of a rotary gas valve; and 2 FIG. 4 is a plan view of a rotary selector switch.
4 FIG. 1 illustrates a gas leak sensor system 10 embodying the invention. This sensor system detects the presence of any gas 6 leaking from a plurality of test spaces 11 - 16, respective ly.
7 These may be confined spaces such as a refrigeration case with a 8 refrigeration coil 17 therein and with some means to direct air 9 over the coil 17 as shown in FIG. 1. A plurality of tubes 18 extend from each of the test spaces to a sensor location which is 11 preferably at a central location. A leaking gas sensor 19 is at 12 this sensor location and is designed to detect the presence of any 13 leaking gas. In this particular embodiment this would be a 14 refrigerant gas such as one of the freon gases. The gas sensor 19 has an alarm 20, which may be visible or audible or both. A
1 controller 22 controls a group of selector valves 24. In this 2 embodiment these may be solenoid actuated valves all connected to 3 a manifold 25. One group of valves 26 is connected one each in 4 each of the tubes 18 leading to the test spaces. These valves are preferably at the sensor location. Valves 27, 28, and 29 are 6 connected between the manifold and a first gas source 31, a second 7 gas source 32, and a gas tank 33, respectively. Each of these 8 sources and the gas tank are sources of the same gas which the 9 sensor 19 tests for leaks . A vacuum pump 30 is a means connected to draw air out of the sensor 19 and to eject it to outside air at 11 a first location 34. A conduit 35 leads from the manifold 25 12 through a three-way valve 36 and a conduit 37 to the gas sensor 19.
13 A gauge 38 is connected to the conduit 37. A conduit 39 connects 14 an input of the three-way valve 36 with another three-way valve 40 to which a nitrogen tank 41 is connected as well as a purge air 16 input from the outside air at 42 which is at a second location 17 remote from the first location 34 so that there is no mixing of air 18 outlet from the vacuum pump with the purge air input.
19 FIG. 2 shows the construction of the tubes such as tube 18 as it terminates at one of the test spaces 11 - 16. The small 21 diameter tube may be a flexible plastic tube, e.g. 1/4" diameter, 22 but at the termination end shown in FIG. 2 the tube is enlarged to 23 perhaps 5/8" diameter for the terminal end 21 which has aperture 24 23.
In operation, the circuit of FIG. 1 is controlled by the 26 controller 22, which preferably is central processing unit or a CPU
27 to control the various valves the selector valve means 24.
of 1 The vacuum pump 30 draws air from the test spaces 11 - 16 which in 2 this example is a refrigerated coil environment which may be 3 subject to leaks of the refrigerant gas. The vacuum pump draws 4 air through the gas sensor 19 and exhausts this air to the outside at the first location 34. After the first test space 11 has been 6 tested, then the controller controls the three-way valve 36 so that 7 purge air is drawn in from the second outside location 42 to purge 8 the sensor of any remaining gas therein. The next selected test 9 space is chosen by opening the proper valve 26 and this might be the test space 12. The vacuum pump draws the air from this test 11 space through the gas sensor to determine if there is any gas 12 leaking in this test space 12. Next, again, the three-way valve 13 36 is actuated to draw purge air through the gas sensor. This 14 purging occurs each time a different tube is selected and whenever the sensor detects refrigerant. If refrigerant gas is detected, 16 then the gas sensor is purged with air and that same test space is 17 again tested before the alarm 20 is activated. This helps 18 eliminate false readings and to make sure that a leak is detected 19 in the correct tube. When for some strange reason freon is sensed from the outside air source, a special alarm sounds and the system 21 shuts down. In this case the system 10 can shift to and sample an 22 inert gas such as nitrogen from the tank 41 by activating the 23 three-way valve 40. An alarm will also sound when the tank 24 pressure is too low to provide sufficient purging gas.
When the system is first started, the vacuum pump 30 is 26 activated and monitored for correct amount of the vacuum. If the 1 vacuum is not correct, the system alarms and shuts down or an 2 alternate vacuum source is selected. If vacuum is correct, the 3 system samples the first outside gas source 31 and verifies correct 4 operation. If not correct, the alternate second source 32 is 5 sampled. If this is still not correct, the compressed tank source 6 33 is sampled and verified. If verification is o.k., the system 7 continues in operation, but an alarm is registered that this source 8 is being used as it is exhaustible.
A gas leak sensor system detects the presence of a gas leaking 11 into any one of a plurality of test spaces and includes a plurality 12 of tubes extending from each of the test spaces to a sensor 13 location. Selector valve means are connected to each tube and a 14 gas sensor has an alarm. Control means is connected to actuate the selector valve means to select tubes in a particular order, means 16 is connected to the selector valve means to draw air and any 17 leaking gas through the selected tube and through the gas sensor, 18 and means to purge said gas sensor at least when leaking gas has 19 been sensed. Accordingly, a gas leak sensor system is disclosed which can sense a plurality of test spaces with a means to purge 21 the gas sensor after the sensing of leaking gas.
22 Another object of an aspect of the invention is to provide a 23 purging means which uses outside air from a location separate from 24 the discharge from said gas sensor.
1 In accordance with one aspect of the present invention, there 2 is provided a gas leak sensor system for detecting the presence of 3 gas leaking into any of a plurality of test spaces, comprising, in 4 combination:
a plurality of tubes extending from each of the test 6 spaces to a sensor location;
7 selector valve means connected to each tube;
8 a gas sensor having an alarm;
9 control means to actuate said selector valve means to select tubes in a particular order;
11 means connected to the selector valve means to draw air 12 and any leaking gas through the selected tube and through the gas 13 sensor;
14 means to purge said gas sensor at least when leaking as has been sensed; and I6 said purging means having a purging gas inlet remote from 17 said test spaces.
18 Other objects and a fuller understanding of the invention may 19 be had by referring to the following description and claims, taken in conjunction with the accompanying drawings.
22 FIG. 1 is a schematic diagram of the gas leak sensor system 23 according to the invention;
24 FIG. 2 is an enlarged view of the termination of an individual tube at a test space;
2a 1 FIG. 3 is a plan view of a rotary gas valve; and 2 FIG. 4 is a plan view of a rotary selector switch.
4 FIG. 1 illustrates a gas leak sensor system 10 embodying the invention. This sensor system detects the presence of any gas 6 leaking from a plurality of test spaces 11 - 16, respective ly.
7 These may be confined spaces such as a refrigeration case with a 8 refrigeration coil 17 therein and with some means to direct air 9 over the coil 17 as shown in FIG. 1. A plurality of tubes 18 extend from each of the test spaces to a sensor location which is 11 preferably at a central location. A leaking gas sensor 19 is at 12 this sensor location and is designed to detect the presence of any 13 leaking gas. In this particular embodiment this would be a 14 refrigerant gas such as one of the freon gases. The gas sensor 19 has an alarm 20, which may be visible or audible or both. A
1 controller 22 controls a group of selector valves 24. In this 2 embodiment these may be solenoid actuated valves all connected to 3 a manifold 25. One group of valves 26 is connected one each in 4 each of the tubes 18 leading to the test spaces. These valves are preferably at the sensor location. Valves 27, 28, and 29 are 6 connected between the manifold and a first gas source 31, a second 7 gas source 32, and a gas tank 33, respectively. Each of these 8 sources and the gas tank are sources of the same gas which the 9 sensor 19 tests for leaks . A vacuum pump 30 is a means connected to draw air out of the sensor 19 and to eject it to outside air at 11 a first location 34. A conduit 35 leads from the manifold 25 12 through a three-way valve 36 and a conduit 37 to the gas sensor 19.
13 A gauge 38 is connected to the conduit 37. A conduit 39 connects 14 an input of the three-way valve 36 with another three-way valve 40 to which a nitrogen tank 41 is connected as well as a purge air 16 input from the outside air at 42 which is at a second location 17 remote from the first location 34 so that there is no mixing of air 18 outlet from the vacuum pump with the purge air input.
19 FIG. 2 shows the construction of the tubes such as tube 18 as it terminates at one of the test spaces 11 - 16. The small 21 diameter tube may be a flexible plastic tube, e.g. 1/4" diameter, 22 but at the termination end shown in FIG. 2 the tube is enlarged to 23 perhaps 5/8" diameter for the terminal end 21 which has aperture 24 23.
In operation, the circuit of FIG. 1 is controlled by the 26 controller 22, which preferably is central processing unit or a CPU
27 to control the various valves the selector valve means 24.
of 1 The vacuum pump 30 draws air from the test spaces 11 - 16 which in 2 this example is a refrigerated coil environment which may be 3 subject to leaks of the refrigerant gas. The vacuum pump draws 4 air through the gas sensor 19 and exhausts this air to the outside at the first location 34. After the first test space 11 has been 6 tested, then the controller controls the three-way valve 36 so that 7 purge air is drawn in from the second outside location 42 to purge 8 the sensor of any remaining gas therein. The next selected test 9 space is chosen by opening the proper valve 26 and this might be the test space 12. The vacuum pump draws the air from this test 11 space through the gas sensor to determine if there is any gas 12 leaking in this test space 12. Next, again, the three-way valve 13 36 is actuated to draw purge air through the gas sensor. This 14 purging occurs each time a different tube is selected and whenever the sensor detects refrigerant. If refrigerant gas is detected, 16 then the gas sensor is purged with air and that same test space is 17 again tested before the alarm 20 is activated. This helps 18 eliminate false readings and to make sure that a leak is detected 19 in the correct tube. When for some strange reason freon is sensed from the outside air source, a special alarm sounds and the system 21 shuts down. In this case the system 10 can shift to and sample an 22 inert gas such as nitrogen from the tank 41 by activating the 23 three-way valve 40. An alarm will also sound when the tank 24 pressure is too low to provide sufficient purging gas.
When the system is first started, the vacuum pump 30 is 26 activated and monitored for correct amount of the vacuum. If the 1 vacuum is not correct, the system alarms and shuts down or an 2 alternate vacuum source is selected. If vacuum is correct, the 3 system samples the first outside gas source 31 and verifies correct 4 operation. If not correct, the alternate second source 32 is 5 sampled. If this is still not correct, the compressed tank source 6 33 is sampled and verified. If verification is o.k., the system 7 continues in operation, but an alarm is registered that this source 8 is being used as it is exhaustible.
9 Next the port selection solenoid valves 26 are activated in a given order and each monitored port is selected and sampled for 11 a period of time. If the port is free from contaminated gas, the 12 next port is sequentially selected until all ports are selected in 13 turn. After each port is sampled, or after each port is sampled 14 which has a gas leak detected, the purge gas is selected to cleanse the sensor to insure that the new port selected starts out with a 16 cleanly purged sensor to help eliminate spurious readings. Should 17 a port indicate that it has contaminated gas present, then the 18 control system stays at that particular port, shuts off that port, 19 and then selects the purge port to cleanse the sensor. The system then tries the contaminated port again and if the level of gas is 21 still above alarming conditions, the system then sends out its 22 alarm to alert personnel of a gas leak. The system shuts off ti~at 23 port, purges the sensor, and then selects the next sequential port.
24 It may be the case that several refrigeration coils or refrigeration cases could be connected in series together sharing ?12176 1 the same environment so that several alarms could come from a 2 single refrigerant leak.
3 As shown in FIG. 2 the terminal end of each tube at the test 4 space is enlarged and this prevents frost from plugging the end of the 1/4" tubing, without need for use of a heater. This enlarged 6 terminal area collects the frost until the refrigerated coil goes 7 through a defrost cycle. Should the end of the tube plug up for 8 whatever reason, then the vacuum gauge 38 in the circuit registers 9 too much of a vacuum and alarms the circuit of an indication that the tube is not sampling the monitored air. Also the gauge 38 can 11 be set for the opposite of that condition which would be an open 12 or cut tube. By having the manifold at a central location, this 13 can establish substantially equal vacuum amounts for each test 14 space so that they all read approximately the same amount of vacuum. Then when a portion of the tube resistance is missing, the 16 vacuum gauge notes the difference in resistance and alarms the 17 circuit.
18 The controller 22 has a timer so that once every 24 hours a 19 calibrated leak from the first source 31 or gas tank 33 is sampled.
If the systems responds properly to the calibrated leak, the normal 21 sequence of operation continues. Should the sensor system 10 not 22 respond to this leak, the system shuts down and alarms.
23 FIG. 3 illustrates a type of gatling gun rotary valve 44 with 24 a plurality of tubes 45 leading to the various test spaces 11 - 16.
A purge air inlet manifold 46 is connected to alternate ones of the 26 conduits around the periphery of the rotary valve 44. The center -_, 1 48 of the.gas valve leads to the gas sensor 19. This therefore 2 ' becomes the selector valve means in place of the selector' valve 3 means 24 of FIG. 1. In use, the selector valve 44 rotates in one 4 direction to test each test space in sequence with the gas sensor 19 being purged of any contaminated gas in between each testing of 6 a test space.
7 FIG. 4 is a similar system with a rotary selector switch 50.
8 A rotary arm 54 can rotate among a plurality of contacts 51.
9 Alternate ones of these contacts go to individual solenoid actuated valves 52 which select individual conduits going to the different 11 test spaces 11 - 16. Alternate ones of these contacts 51 lead to 12 a common conductor 55 which energizes a purge valve 53.. Again the 13 rotation of the selector arm 54 in a given direction will 14 individually test the various test spaces 11 - 16 with purging ' between each testing of a test space.
16 The present disclosure includes that contained in the appended 17 claims, as well as that of the forgoing description. Although this 18 invention has been described in its preferred form with a certain 19 degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of 21 example and that numerous changes in the details of construction 22 and the combination and arrangement of parts may be resorted to 23 without departing from the spirit and the scope of the invention 24 as hereinafter claimed.
24 It may be the case that several refrigeration coils or refrigeration cases could be connected in series together sharing ?12176 1 the same environment so that several alarms could come from a 2 single refrigerant leak.
3 As shown in FIG. 2 the terminal end of each tube at the test 4 space is enlarged and this prevents frost from plugging the end of the 1/4" tubing, without need for use of a heater. This enlarged 6 terminal area collects the frost until the refrigerated coil goes 7 through a defrost cycle. Should the end of the tube plug up for 8 whatever reason, then the vacuum gauge 38 in the circuit registers 9 too much of a vacuum and alarms the circuit of an indication that the tube is not sampling the monitored air. Also the gauge 38 can 11 be set for the opposite of that condition which would be an open 12 or cut tube. By having the manifold at a central location, this 13 can establish substantially equal vacuum amounts for each test 14 space so that they all read approximately the same amount of vacuum. Then when a portion of the tube resistance is missing, the 16 vacuum gauge notes the difference in resistance and alarms the 17 circuit.
18 The controller 22 has a timer so that once every 24 hours a 19 calibrated leak from the first source 31 or gas tank 33 is sampled.
If the systems responds properly to the calibrated leak, the normal 21 sequence of operation continues. Should the sensor system 10 not 22 respond to this leak, the system shuts down and alarms.
23 FIG. 3 illustrates a type of gatling gun rotary valve 44 with 24 a plurality of tubes 45 leading to the various test spaces 11 - 16.
A purge air inlet manifold 46 is connected to alternate ones of the 26 conduits around the periphery of the rotary valve 44. The center -_, 1 48 of the.gas valve leads to the gas sensor 19. This therefore 2 ' becomes the selector valve means in place of the selector' valve 3 means 24 of FIG. 1. In use, the selector valve 44 rotates in one 4 direction to test each test space in sequence with the gas sensor 19 being purged of any contaminated gas in between each testing of 6 a test space.
7 FIG. 4 is a similar system with a rotary selector switch 50.
8 A rotary arm 54 can rotate among a plurality of contacts 51.
9 Alternate ones of these contacts go to individual solenoid actuated valves 52 which select individual conduits going to the different 11 test spaces 11 - 16. Alternate ones of these contacts 51 lead to 12 a common conductor 55 which energizes a purge valve 53.. Again the 13 rotation of the selector arm 54 in a given direction will 14 individually test the various test spaces 11 - 16 with purging ' between each testing of a test space.
16 The present disclosure includes that contained in the appended 17 claims, as well as that of the forgoing description. Although this 18 invention has been described in its preferred form with a certain 19 degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of 21 example and that numerous changes in the details of construction 22 and the combination and arrangement of parts may be resorted to 23 without departing from the spirit and the scope of the invention 24 as hereinafter claimed.
Claims (14)
1. A gas leak sensor system for detecting the presence of gas leaking into any of a plurality of test spaces, comprising, in combination:
a plurality of tubes extending from each of the test spaces to a sensor location;
selector valve means connected to each tube;
a gas sensor having an alarm;
control means to actuate said selector valve means to select tubes in a particular order;
means connected to the selector valve means to draw air and any leaking gas through the selected tube and through the gas sensor;
means to purge said gas sensor at least when leaking as has been sensed; and said purging means having a purging gas inlet remote from said test spaces.
a plurality of tubes extending from each of the test spaces to a sensor location;
selector valve means connected to each tube;
a gas sensor having an alarm;
control means to actuate said selector valve means to select tubes in a particular order;
means connected to the selector valve means to draw air and any leaking gas through the selected tube and through the gas sensor;
means to purge said gas sensor at least when leaking as has been sensed; and said purging means having a purging gas inlet remote from said test spaces.
2. A gas leak sensor system as set forth in claim 1, wherein said purging means purges said gas sensor to outside air at a first location.
3. A gas leak sensor system as set forth in claim 2, wherein said purging means has an air inlet remote from said first location.
4. A gas leak sensor system as set forth in claim 1, wherein said purging means purges said gas sensor with outside air after each sensing of a selected tube.
5. A gas leak sensor system as set forth in claim 1, wherein said selector valve means are grouped at said sensor location.
6. A gas leak sensor system as set forth in claim 1, including an air inlet connected to outside air in said purge means and connected through said selector valve means to said sensor so that when the valve means is open outside air purges said sensor.
7. A gas leak sensor system as set forth in claim 1, including said alarm connected to said gas sensor to provide an alarm upon sensing gas in the gas sensor.
8. A gas leak sensor system as set forth in claim 1, including said sensor having an output to said control means to control said selector valve means.
9. A gas leak sensor system as set forth in claim 8, wherein said control means controls said selector valve means to check twice for gas leaking into a given test space prior to giving an alarm.
10. A gas leak sensor system as set forth in claim 8, wherein said control means controls said selector valve means to purge said gas sensor in between two drawings of air from a given test space before giving an alarm of leaking gas.
11. A gas, leak sensor system as set forth in claim 1, including vacuum gauge means in communication with said sensor.
12. A gas leak sensor system as set forth in claim 1, wherein said drawing means is a vacuum pump.
13. A gas leak sensor system as set forth in claim 1, wherein said particular order of said selected tubes is to alternate a selected tube with the selection of said purging means.
14. A gas leak sensor system as set forth in claim 1, wherein said purge means includes an inert gas.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/938,820 | 1992-09-01 | ||
| US07/938,820 US5293771A (en) | 1992-09-01 | 1992-09-01 | Gas leak sensor system |
| PCT/US1993/007973 WO1994005992A1 (en) | 1992-09-01 | 1993-08-25 | Gas leak sensor system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2121476A1 CA2121476A1 (en) | 1994-03-17 |
| CA2121476C true CA2121476C (en) | 2003-10-21 |
Family
ID=25472025
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002121476A Expired - Fee Related CA2121476C (en) | 1992-09-01 | 1993-08-25 | Gas leak sensor system |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US5293771A (en) |
| JP (1) | JPH07500921A (en) |
| CN (1) | CN1072358C (en) |
| BR (1) | BR9305627A (en) |
| CA (1) | CA2121476C (en) |
| DE (2) | DE4394398C2 (en) |
| GB (1) | GB2275540B (en) |
| MX (1) | MX9305319A (en) |
| WO (1) | WO1994005992A1 (en) |
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| US2826044A (en) * | 1956-02-08 | 1958-03-11 | Guy J Reer | Alarm mechanism for refrigeration systems |
| US3043145A (en) * | 1958-06-10 | 1962-07-10 | Bailey Meter Co | Gas sample scanning apparatus |
| US3234749A (en) * | 1962-07-31 | 1966-02-15 | Lester K Quick | Compound refrigeration system |
| US3357257A (en) * | 1966-01-28 | 1967-12-12 | Ree Du | Gas sampling and detecting system |
| DE2334886A1 (en) * | 1973-07-09 | 1975-01-30 | Leybold Heraeus Gmbh & Co Kg | Leak detector method of operation - has tested samples connected to the leak detector vacuum system or placed in a sample space |
| JPS5083832A (en) * | 1973-11-28 | 1975-07-07 | ||
| CH583415A5 (en) * | 1974-06-28 | 1976-12-31 | Cerberus Ag | |
| US3921457A (en) * | 1974-11-01 | 1975-11-25 | Texaco Inc | System for monitoring the atmosphere in petroleum product tanks |
| DE2816687A1 (en) * | 1978-04-18 | 1979-10-31 | Leybold Heraeus Gmbh & Co Kg | Testing integrity of hollow article - involves using leak detection procedure by placing article in sealed test chamber |
| JPS5583832A (en) * | 1978-12-20 | 1980-06-24 | Hitachi Ltd | Differential pressure type sodium leak detection method |
| US4356721A (en) * | 1980-12-19 | 1982-11-02 | The United States Of America As Represented By The Secretary Of The Army | Glass lead seal test apparatus |
| US4612775A (en) * | 1984-05-04 | 1986-09-23 | Kysor Industrial Corporation | Refrigeration monitor and alarm system |
| JPS6484127A (en) * | 1987-09-28 | 1989-03-29 | Hitachi Ltd | Leak water detector |
| US5009076A (en) * | 1990-03-08 | 1991-04-23 | Temperature Engineering Corp. | Refrigerant loss monitor |
| JP3245100B2 (en) * | 1997-09-16 | 2002-01-07 | キヤノン株式会社 | Method for manufacturing semiconductor element and method for manufacturing solar cell |
-
1992
- 1992-09-01 US US07/938,820 patent/US5293771A/en not_active Expired - Lifetime
-
1993
- 1993-08-25 GB GB9407436A patent/GB2275540B/en not_active Expired - Fee Related
- 1993-08-25 DE DE4394398A patent/DE4394398C2/en not_active Expired - Fee Related
- 1993-08-25 BR BR9305627A patent/BR9305627A/en not_active IP Right Cessation
- 1993-08-25 DE DE4394398T patent/DE4394398T1/en active Pending
- 1993-08-25 CA CA002121476A patent/CA2121476C/en not_active Expired - Fee Related
- 1993-08-25 JP JP6507275A patent/JPH07500921A/en active Pending
- 1993-08-25 WO PCT/US1993/007973 patent/WO1994005992A1/en active Application Filing
- 1993-09-01 MX MX9305319A patent/MX9305319A/en unknown
- 1993-09-01 CN CN93118815A patent/CN1072358C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2121476A1 (en) | 1994-03-17 |
| CN1104325A (en) | 1995-06-28 |
| BR9305627A (en) | 1995-03-01 |
| MX9305319A (en) | 1994-03-31 |
| WO1994005992A1 (en) | 1994-03-17 |
| CN1072358C (en) | 2001-10-03 |
| DE4394398T1 (en) | 1994-11-10 |
| GB9407436D0 (en) | 1994-06-22 |
| JPH07500921A (en) | 1995-01-26 |
| US5293771A (en) | 1994-03-15 |
| DE4394398C2 (en) | 1996-09-19 |
| GB2275540A (en) | 1994-08-31 |
| GB2275540B (en) | 1995-09-06 |
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