Method and apparatus for testing leakage rate

• US 3,918,291 A
• Filed: 05/07/1974
• Issued: 11/11/1975
• Est. Priority Date: 03/05/1973
• Status: Expired due to Term

• Current Assignee: Joachim W. Pauly, Wilbur Stanley Leinberry
• Original Assignee: Joachim W. Pauly, Wilbur Stanley Leinberry
• Inventors: Pauly, Joachim W., Leinberry, Wilbur Stanley
• Primary Examiner(s): Queisser, Richard C.
• Assistant Examiner(s): Roskos, Joseph W.
• Application Number:
  US05/467,805
• Time in Patent Office: 553 Days
• Field of Search: 73/40,49.2
• US Class Current: 73/40
• CPC Class Codes: G01D 13/00 Component parts of indicators for measuring arrangements not specially adapted for a specific variable
• CPC Class Codes: G01M 3/3254 using a flow detector G01M3/3245, G01M3/3272 take precedence

Abstract

Method and apparatus for testing the leakage of air from a vessel such as a submarine, by establishing a selected test pressure level in the vessel, establishing a regulated test flow to the vessel, monitoring the pressure in the vessel, and determining whether the leakage rate from the vessel exceeds a predetermined rate by relating the test flow rate to its effect on the pressure level in the vessel. In one mode of operation, a variable test flow is delivered to the vessel and adjusted as needed to maintain pressure in the vessel at the test level, the rate and temperature of this flow are accurately measured when stabilized, and the measured values are converted to standard units. In a second mode of operation, a metered flow rate that is equivalent to the maximum permissible leakage rate is introduced to the vessel, and the effect of this flow on vessel pressure indicates the relation between the actual leakage rate and the test flow rate. Both modes utilize test apparatus including basically conventional components, that can be compactly mounted in a suitcase-like housing, along with tables for converting measured values into standard values.

Claims

1. The method of determining the rate of leakage of air from a submarine in standard units, comprising the steps of:

pressurizing the submarine to a selected approximate level and permitting the temperature thereof to become stabilized;

measuring the stabilized pressure level and adjusting it precisely to a selected test level;

introducing an adjustable test flow of air into the submarine and adjusting the rate of the test flow as required to maintain the selected test level until a stabilized flow rate is obtained and said test level is maintained;

accurately measuring the Flow rate and the temperature of the test flow;

converting the measured test flow rate at the pressure of said test level to an equivalent flow rate at a standard pressure, by applying a first conversion factor determined by the difference between the test pressure and the standard pressure; and

converting the equivalent flow rate at the standard pressure and the measured temperature to an equivalent flow rate at the standard pressure and a standard temperature, by applying a second conversion factor determined by the difference between the measured temperature and the standard temperature.

2. The method defined in claim 1 including the further steps of:

preparing in advance a plurality of pressure reference tables for a plurality of selected test levels, providing first conversion factors for a series of different measured flow rates at each of said test levels;

preparing in advance a temperature reference table providing second conversion factors for a series of different measured temperatures;

selecting the first conversion factor from the pressure reference table for the test level to which the pressure of the submarine is adjusted and maintained; and

selecting from the temperature reference table the conversion factor for the measured temperature.

3. The method of determining the rate of leakage of gas from a pressurized vessel after the vessel has been pressurized and the pressure therein has stabilized, comprising the steps of:

sensing the pressure of the gas in the vessel;

adjusting the pressure of the gas in the vessel to a selected test level;

introducing an adjustable test flow of gas into the vessel and adjusting the rate of said test flow as required to maintain the pressure at the selected test level;

after a stabilized test flow rate is obtained, accurately measuring the flow rate and the temperature of the test flow; and

converting the measured flow rate at the measured temperature and the test pressure level to an equivalent flow rate at a standard pressure level and a standard temperature.

4. The method as defined in claim 3 in which the measured flow rate is converted to an equivalent flow rate by:

applying a pressure conversion factor determined by the difference between the selected test level and the standard pressure; and

applying a temperature conversion factor determined by the difference between the measured temperature and the standard temperature.

5. The method as defined in claim 4 including the further steps of:

preparing in advance a plurality of reference tables for a plurality of selected test levels, providing pressure conversion factors for a series of different measured flow rates at each of said test levels; and

selecting the pressure conversion factor from one of the reference tables after measuring the flow rate at the selected test level.

6. The method as defined in claim 5 including the further steps of:

preparing in advance a reference table providing temperature conversion factors for a series of different measured temperatures; and

selecting the temperature conversion factor from the reference table after measuring the temperature.

7. The method of testing whether the rate of leakage of gas from a pressurized vessel exceeds a preselected leakage rate at a selected pressure level, comprising the steps of:

establishing the selected pressure level in the vessel;

introducing a variable test flow of gas under pressure into the vessel;

monitoring the pressure level in the vessel while said test flow is being introduced;

adjusting the test flow as necessary to maintain said selected pressure level; and

measuring said test flow while said pressure level is maintained constant.

8. The method of testing whether the leakage rate of gas from a pressurized vessel exceeds a preselected leakage rate, at a selected pressure level, comprising the steps of:

establishing the selected pressure level in tHe vessel;

introducing a metered constant test flow of gas into the vessel at a rate equal to said preselected leakage rate; and

monitoring the pressure level to determine from changes therein whether the metered flow is less than the actual leakage rate, as indicated by a drop in said pressure level.

9. The method as defined in claim 8 in which said test flow is metered by supplying gas under pressure higher than said selected pressure level through an orifice capable of delivering a flow equal to said preselected leakage rate while a predetermined pressure differential is maintained across the orifice, and by maintaining said predetermined pressure differential until a pressure trend is detected in said vessel.

10. The method as defined in claim 8 including the further steps of accurately measuring the temperature of said test flow, and modifying said test flow to compensate for temperature differential.

11. Apparatus for determining the rate of leakage of gas from a pressurized vessel with a source of gas under pressure, comprising:

means forming an inlet for connection to the source of gas under pressure and an outlet for connection to the vessel;

means defining a main flow conduit through said apparatus between said inlet and said outlet;

a flow meter for accurately measuring the rate of flow through said main flow conduit;

a temperature monitor for accurately measuring the temperature of gas flowing through said main flow conduit;

means for accurately indicating the pressure of gas in said vessel; and

means for controlling the rate of flow through said main flow conduit and adjusting the flow rate to maintain the pressure of gas in said vessel at a selected test level, whereby the rate and temperature of the flow equal to the leakage from said vessel can be measured and the flow rate can be converted to standard units by application of temperature and pressure conversion factors determined by pressure indicated by said indicating means and the temperature measured by said temperature monitor.

12. Apparatus as defined in claim 11 further including a secondary flow conduit from said inlet and said outlet, by-passing said main flow conduit, and selectively operable means for controlling flow through said secondary conduit to increase the pressure of gas in said vessel to a selected test level.

13. Apparatus as defined in claim 12 further including selectively operable means for bleeding gas from said vessel to reduce the pressure therein to a selected test level.

14. Apparatus as defined in claim 11 further including a pressure regulator in said main flow conduit between said inlet and said rate-controlling means for maintaining a preselected pressure in said main flow conduit.

15. Apparatus as defined in claim 11 in which said rate-controlling means is a valve having a selectively movable valve member for varying the flow area through the valve.

16. Apparatus as defined in claim 11 in which said pressure-indicating means is a pressure gauge communicating with said main flow conduit to indicate the pressure therein adjacent said outlet.

17. Apparatus as defined in claim 11 in which the elements of the apparatus are mounted in a portable case.

18. Apparatus for testing whether the rate of leakage of gas from a pressurized vessel exceeds a preselected leakage rate at a selected pressure level, with a source of gas under pressure higher than said pressure level, comprising:

means forming an inlet for connection to the source and an outlet for connection to the vessel;

means defining a flow conduit between said inlet and said outlet;

gauge means for indicating changes in the pressure of gas in the vessel; and

means for regulating the rate of flow through said flow conduit from the source to the vessel, and establishing the flow at a known rate, whereby the leakage rate can be determined in relation to said known rate from its effect on the pressure in the vessel, including an orifIce capable of delivering a flow rate equal to said preselected leakage rate when a predetermined pressure differential is establshed across said orifice, and means for establishing and maintaining said predetermined pressure differential across said orifice.

19. Apparatus as defined in claim 18 in which the means for establishing and maintaining said pressure differential comprises an adjusting valve for regulating the flow to said orifice from the source, and a gauge for indicating the pressure differential across said orifice.

20. Apparatus as defined in claim 18 in which said gauge means comprise a gauge having a first indicator for indicating the existing pressure level in the vessel, and a second indicator selectively positionable at the position of said first indicator, to indicate the initial pressure level and thereby facilitate the detection of changes in the pressure level.

21. Apparatus as defined in claim 18 in which said regulating means include a flow regulator for adjusting the flow through said conduit until the flow maintains the pressure in the vessel constant, and a flow meter for accurately measuring the adjusted flow.