Method and apparatus for sampling and detecting gases in a fluid

• US 5,357,781 A
• Filed: 01/22/1993
• Issued: 10/25/1994
• Est. Priority Date: 01/22/1993
• Status: Expired due to Fees

• Current Assignee: Sentech Incorporated (General Dynamics Corporation)
• Original Assignee: Sentech Incorporated (General Dynamics Corporation)
• Inventors: Tikijian, George H.
• Primary Examiner(s): Raevis, Robert
• Assistant Examiner(s): BROCK, MICHAEL J
• Application Number:
  US08/008,369
• Time in Patent Office: 641 Days
• Field of Search: 340/632, 73/19.01, 73/19.1, 73/19.12
• US Class Current: 73/19.1
• CPC Class Codes: G01N 33/0011 Sample conditioning in general G01N1/28
• CPC Class Codes: G01N 33/0052 for gaseous halogens
• CPC Class Codes: G01N 33/0063 using a threshold to release an alarm or displaying means alarm arrangements G08B, e.g. fire alarm actuated by the presence of smoke or gases G08B17/10, for other abnormal conditions G08B21/00

Abstract

There is disclosed a method and apparatus for repetitively taking samples of a predetermined quantity of a test gas in a liquid and introducing these samples to a test chamber. Each sample is agitated to release therefrom the test gas. The released gas is then conveyed to a sensor, which monitors the released gas for the presence of a concentration above the threshold level to produce an alarm indicative thereof. The samples of the test gas in a liquid may be repetitively taken from one zone of a plurality at a time until each zone is sampled. After one sample has been tested in the test chamber, it is discharged therefrom and the test chamber is flushed with a sample of the liquid and test gas taken from the next zone of the plurality before introducing the next sample from the same, next zone.

Claims

1. A method of monitoring a liquid containing a test gas at each of a plurality of zones and of determining the concentration of the test gas within the liquid above a threshold level, said method comprising a repetitively taking Of one sample of the liquid at a time at each of the plurality of zones;

for each sample, said sample taking comprising the steps of;

a) conveying the one sample of the liquid from the one zone to a test chamber;

b) separating the test gas from the one sample of the liquid conveyed to the test chamber;

c) conveying the test gas released into the test chamber from the one sample of the liquid taken from the test chamber to a sensor;

d) operating the sensor to detect the presence of the released test gas of a concentration above the threshold level to produce an alarm indicative thereof;

e) discharging the one sample taken from the one zone from the test chamber; and

f) flushing the one sample taken from the one zone from the test chamber with the liquid taken from another zone of the plurality of zones before introducing the next sample of liquid from the other zone into the test chamber.

2. The monitoring method of claim 1, wherein a sampling sequence comprises the steps of taking a series of samples, one from each zone of the plurality of zones in a given order.

3. The monitoring method of claim 2, wherein the sampling sequence is repetitively operated to continuously monitor the gas and liquid in each of the plurality of zones.

4. The method of monitoring of claim 3, wherein there is further included the step of responding to an alarm to identify a corresponding one zone of the plurality of zones from which the sample was taken with a concentration of the test gas above the threshold level, and of deleting the sampling of that identified zone from the subsequent sampling sequences.

5. The method of monitoring of claim 1, wherein for each sample, said sample taking further comprises the steps of taking one sample of the ambient atmosphere and of conveying that sample to the sensor, and of operating the sensor to detect the presence of the test gas in the ambient atmosphere of a concentration above the threshold level to produce an alarm indicating that the detecting of the released gas from a sample of the liquid may be contaminated.

6. The method of monitoring of claim 1, wherein the series of steps following the taking of each sample is repeated to produce a repetitive cycle of steps.

7. The method of monitoring of claim 6, wherein each of said repetitive cycles comprises a further step of taking and conveying a sample of the ambient atmosphere to the sensor before carrying out step c).

8. The method of monitoring of claim 7, further comprising the steps of operating the sensor to take a first reading of the concentration of the test gas in the ambient atmosphere and to take a second reading of the concentration of the test gas in the liquid, and taking and displaying the difference between the first and second readings.

9. The method of monitoring as claimed in claim 7, wherein the step of taking the sample of the ambient atmosphere is carried out during step f) prior to the taking of the next sample of the liquid.

10. The method of monitoring of claim 7, wherein a period between consecutive sampling cycles is varied.

11. A method of monitoring for the presence of a test gas in both of a liquid and of an ambient atmosphere of a concentration above a threshold level, said method comprising a repetitively taking and introducing a series of first samples of the liquid into a test chamber;

for each first sample, said sample taking comprising the steps of;

a) separating the test gas from the liquid of each first sample of the series introduced into the test chamber;

b) conveying the separated test gas of each first sample to a gas sensor;

c) repetitively operating the gas sensor to detect whether the concentration of each separated test gas of each first sample is above the threshold level and, if so, to provide an alarm; and

d) taking and conveying a second sample of the ambient atmosphere to the gas sensor, before operating the sensor to detect whether the concentration of the test gas in the second sample in the ambient atmosphere is above the threshold level and, if so, to provide an alarm indicating that the test gas in the atmosphere may be contaminating a detection by the sensor of the presence of the test gas in the next first sample.

12. Apparatus for taking first samples of a liquid containing a test gas from a plurality of corresponding first spaces and taking second samples of a mixture of the test gas and another gas from a plurality of corresponding second spaces, and for monitoring each of the first and second samples for the presence of the test gas of a concentration above a threshold level, said apparatus comprising:

a) a plurality of first actuable valves, each of said first actuable valves being connected to a corresponding one of the plurality of first spaces;

b) a plurality of second actuable valves, each of said second actuable valves being connected to a corresponding one of the plurality of second spaces;

c) a test chamber connected with each of said first actuable valves for receiving one first sample at a time from an actuated one of said plurality of first actuable valves;

d) means for separating the test gas from the liquid of the one first sample in said test chamber;

e) gas detecting means in communication with said test chamber for receiving the separated test gas from the one first sample and with each of said second actuable valves for receiving one second sample at a time from an actuated one of said plurality of second actuable valves; and

f) controlling means connected with each of said pluralities of said first actuable valves and of said second actuable valves for selectively actuating only one of said first and second actuable valves at a time to permit the detection by said gas detecting means of the test gas in only one the first or second samples at a time.

13. The sample taking apparatus of claim 12, wherein said controlling means repetitively carries out a test cycle for each first actuable valve of said plurality, comprising means operative during each test cycle for successively opening one first actuable valve of said plurality, means for thereafter operating said separating means to separate the test gas from the liquid of the first sample in said test chamber and means for thereafter operating said gas detecting means to detect the test gas from the one first sample.

14. The sample taking apparatus of claim 13, wherein said controlling means further comprises second means for opening only one second valve of said plurality for a fixed time, before closing said one second actuable valve and opening the next second actuable valve of said plurality.

15. The sample taking apparatus of claim 14, wherein said first means defeats said second means from opening said second valves at least during the operation of said gas detecting means in the test cycle to sense the separated gas from the one first sample.

17. The monitoring apparatus of claim 15, wherein said agitating means comprises propeller means positioned to engage each sample of said series within said test chamber and motor means coupled to rotatively drive said propeller means.

18. The monitoring apparatus of claim 17, wherein said control means upon the introduction of one sample of said series into said test chamber actuates said motor means for a fixed period of time.

16. Apparatus for monitoring a series of samples of a liquid containing a test gas for the presence of the test gas of a concentration above a threshold level, said apparatus comprising:

a) means for defining a test chamber;

b) means for repetitively taking and introducing the series of samples into said test chamber, each sample of said series being of a predetermined quantity;

c) means for agitating each sample of said series within said test chamber to release the test gas from that sample;

d) sensor means for detecting the presence of the test gas of the concentration above the threshold level to provide an alarm indicative thereof;

e) means for repetitively conveying the released gas of each sample of said series from said test chamber to said sensor means; and

f) means coupled to said agitating means and, upon the introduction of each sample of the series into said test chamber, for operating said agitating means to provide each sample with a predetermined quantity of agitation.

19. Apparatus for monitoring a series of samples of a liquid containing a test gas for the presence of the test gas of a concentration above a threshold level, said apparatus comprising:

a) means for defining a test chamber;

b) means for repetitively taking and introducing the series of samples into said test chamber, each sample of said series being of a predetermined quantity;

c) means for agitating each sample of said series within said test chamber to release the test gas from that sample;

d) sensor means for detecting the presence of the test gas of the concentration above the threshold level to provide an alarm indicative thereof;

e) means for repetitively conveying the released gas of each sample of said series from said test chamber to said sensor means; and

f) control means responsive to the operation of said agitating means for defeating the operation of said sample taking means and said gas conveying means, whereby said test chamber is sealed to prevent the escape of any released test gas from said test chamber while said agitating means is operative.

20. Apparatus for monitoring a series of samples of a liquid containing a test gas for the presence of the test gas of a concentration above a threshold level, said apparatus comprising:

a) means for defining a test chamber;

b) means for repetitively taking and introducing the series of samples into said test chamber, each sample of said series being of a predetermined quantity, said introducing means comprising flow control means for regulating the introduction of each sample into said test chamber at the same flow rate;

c) means for agitating each sample of said series within said test chamber to release the test gas from that sample;

d) sensor means for detecting the presence of the test gas of the concentration above the threshold level to provide an alarm indicative thereof; and

e) means for repetitively conveying the released gas of each sample of said series from said test chamber to said sensor means.

21. Apparatus for monitoring a series of samples of a liquid containing a test gas for the presence of the test gas of a concentration above a threshold level, said apparatus comprising:

a) means for defining a test chamber;

b) means for repetitively taking and introducing the series of samples into said test chamber, each sample of said series being of a predetermined quantity;

c) means for agitating each sample of said series within said test chamber to release the test gas from that sample;

d) sensor means for detecting the presence of the test gas of the concentration above the threshold level to provide an alarm indicative thereof; and

e) means for repetitively conveying the released gas of each sample of said series from said test chamber to said sensor means, said conveying means comprising flow control means for regulating the conveying of the released gas from each sample to said sensor means to be of substantially the same flow rate.

22. A method of monitoring a series of samples of a liquid containing a test gas for determining the presence of the test gas within one sample above a threshold concentration, said method comprising the repetitively sampling of the liquid to produce a series of samples, each sample being of a predetermined quantity;

for each sample, said sample taking comprising the steps of;

a) introducing one sample of said series into a test chamber;

b) imparting a constant amount of agitation to the one sample of said series within said test chamber to release the test gas from the one sample;

c) conveying the gas released into the test chamber from the one sample of said series to a sensor; and

d) operating the sensor to detect the presence of the released test gas above the threshold concentration to produce an alarm indicative thereof.

23. A method of monitoring a series of samples of a liquid containing a test gas for determining the presence of the test gas within one sample above a threshold concentration, said method comprising the repetitively sampling of the liquid to produce a series of samples, each sample being of a predetermined quantity;

for each sample, said sample taking comprising the steps of;

a) introducing one sample of said series into a test chamber;

b) agitating one sample of said series within said test chamber to release the test gas from that one sample, while sealing the test chamber to prevent the escape of the released test gas from the one sample;

c) conveying the gas released into the test chamber from the one sample of said series to a sensor; and

d) operating the sensor to detect the presence of the released test gas above the threshold concentration to produce an alarm indicative thereof.

24. A method of monitoring a series of samples of a liquid containing a test gas for determining the presence of the test gas within one sample above a threshold concentration, said method comprising the repetitively sampling of the liquid to produce a series of samples, each sample being of a predetermined quantity;

for each sample, said sample taking comprising the steps of;

a) conveying at a flow rate one sample of said series into a test chamber and maintaining constant the flow rate of each sample of the series;

b) agitating the one sample of said series within said test chamber to release the test gas from the one sample;

c) conveying the gas released into the test chamber from the one sample of said series to a sensor; and

d) operating the sensor to detect the presence of the released test gas above the threshold concentration to produce an alarm indicative thereof.

25. A method of monitoring a series of samples of a liquid containing a test gas for determining the presence of the test gas within one sample above a threshold concentration, said method comprising the repetitively sampling of the liquid to produce a series of samples, each sample being of a predetermined quantity;

for each sample, said sample taking comprising the steps of;

a) introducing one sample of said series into a test chamber;

b) agitating one sample of said series within said test chamber to release the test gas from that one sample;

c) conveying the gas released at a flow rate into the test chamber from the one sample of said series to a sensor, and maintaining constant said flow rate; and

d) operating the sensor to detect the presence of the released test gas above the threshold concentration to produce an alarm indicative thereof.