Apparatus and method for detection of a leak in a membrane of a fluid flow control system

• US 6,223,130 B1
• Filed: 11/16/1998
• Issued: 04/24/2001
• Est. Priority Date: 11/16/1998
• Status: Expired due to Term

• Current Assignee: Deka Products Limited Partnership
• Original Assignee: Deka Products Limited Partnership
• Inventors: Gray, Larry, Bryant, Robert, Spencer, Geoffrey
• Primary Examiner(s): WACHSMAN, HAL D
• Application Number:
  US09/193,337
• Time in Patent Office: 890 Days
• Field of Search: 702/51, 702/31, 702/45, 702/50, 702/55, 702/100, 702/114, 702/138, 702/140, 702/176-178, 702/179, 702/182-185, 702/193, 702/FOR.119, 702/FOR.121, 702/FOR.127, 702/FOR.128, 702/FOR.139, 702/FOR.143, 702/FOR.170, 702/FOR.171, 700/281, 700/282, 700/301, 73/40, 73/405.R, 73/405.A, 73/405.8, 73/407, 738/61, 738/610.2, 738/610.3, 738/610.8, 73/85, 73/97, 73/98, 731/02, 736/45, 736/46, 736/53, 737/39, 737/41, 737/82, 736/50, 137/488, 137/513.3, 137/513.5, 137/513.7, 137/312, 137/386, 137/455, 137/458, 137/459, 137/487, 137/551, 137/552.7, 137/557-559, 137/563, 137/571, 137/593, 137/624-1-6, 137/624.18, 137/624.21, 137/624.27, 417/53, 417/63, 417/9, 417/102, 417/103, 377/20, 377/21, 340/605, 340/606, 340/611
• US Class Current: 702/51
• CPC Class Codes: F04B 43/009 leakage control; pump systems with two flexible members; between the actuating element and the pumped fluid
• CPC Class Codes: F04B 51/00 Testing machines, pumps, or pumping installations

Abstract

An apparatus, method, and computer program product for detection of fluid leakage through a membrane in a fluid flow control system. The fluid flow control system has a first chamber and a second chamber. A membrane is disposed between the first chamber and the second chamber. The second chamber has a connection to a pressure tank, the pressure tank has a fluid with a pressure, and the connection defines a fluid path. The method indudes in a first step, blocking the fluid path. The pressure of the fluid in the pressure tank is then adjusted. The pressure is measured in the pressure tank which creates a pressure measurement at each of a first set of multiple timed intervals while the fluid path is blocked and after the pressure is adjusted. A blocked pressure rate is calculated based on the pressure measurements in the pressure tank at the first set of multiple timed intervals. Next, the fluid path is unblocked. The pressure is measured within the pressure tank creating a pressure measurement at each of a second set of multiple timed intervals after the fluid path is unblocked. Then, an unblocked pressure rate is calculated based on the pressure measurements in the pressure tank at the second set of multiple timed intervals. Finally a leakage rate is calculated based on the blocked pressure rate and the unblocked pressure rate. An alarm is caused when the leakage rate becomes greater than a predetermined threshold value.

Claims

1. A method for detecting a leakage rate of fluid through a membrane in a fluid flow control system having a first chamber and a second chamber, the membrane being disposed between the first chamber and the second chamber, the second chamber having a connection to a pressure tank, the pressure tank having a fluid with a pressure, the connection defining a fluid path, the method comprising:

blocking the fluid path;

adjusting the pressure of the fluid in the pressure tank;

measuring the pressure in the pressure tank creating a pressure measurement at each of a first set of multiple timed intervals while the fluid path is blocked and after the pressure in the pressure tank is adjusted;

calculating a blocked pressure rate based on the pressure measurements in the pressure tank at the first set of multiple timed intervals;

unblocking the fluid path;

measuring the pressure within the pressure tank creating a pressure measurement at each of a second set of multiple timed intervals after the fluid path is unblocked;

calculating an unblocked pressure rate based on the pressure measurements in the pressure tank at the second set of multiple timed intervals; and

calculating a leakage rate based on the blocked pressure rate and the unblocked pressure rate.

6. The method according to claim 1, wherein in the step of measuring a pressure at a first set of multiple timed intervals and in the step of measuring a pressure at a second set of multiple timed intervals the pressure is measured with a transducer.

7. The method according to claim 1, wherein in the step of calculating a blocked pressure rate and in the step of calculating an unblocked pressure rate the rates are calculated in a processor.

8. The method according to claim 1, wherein the fluid is air.

9. The method according to claim 1, further comprising after the step of

measuring the pressure at a first set of multiple timed intervals:

storing each of the pressure measurements in a memory unit; and

providing the pressure measurements in the memory unit to a processor.

10. The method according to claim 1, further comprising after the step of

measuring the pressure at a second set of multiple timed intervals;

storing each of the pressure measurements in a memory unit; and

providing the pressure measurements in the memory unit to a processor.

2. The method according to daim 1, further comprising the step of causing an alarm when the leakage rate becomes greater than a predetermined threshold value.

3. The method according to claim 2, wherein the step of causing an alarm occurs in a processor.

4. The method according to claim 2 wherein the alarm is an auditory alarm.

5. The method according to claim 2 wherein the alarm is a visual alarm.

11. A fluid flow control system comprising:

a first chamber;

a second chamber;

a pressure tank containing a fluid having a pressure connected to the second chamber;

a transducer disposed within the pressure tank for creating a pressure signal;

a valve disposed between the second chamber and the pressure tank;

a membrane disposed between the first chamber and the second chamber;

a valve controller connected to the valve;

a pump connected to the pressure tank; and

a processor connected to the transducer, to the pump and to the valve controller for;

a) signaling the valve controller to shut the valve;

b) adjusting the pressure of the fluid in the pressure tank with the pump;

c) reading the pressure signal from the transducer at a first set of predetermined intervals while the valve is shut creating a first set of pressure signal readings;

d) calculating a baseline leak rate based on the first set of pressure signals while the valve is shut;

e) sending a signal to the valve controller to open the valve;

f) reading the pressure signal from the transducer at a second set of predetermined timed intervals creating a second set of pressure signal readings while the valve is open;

g) calculating a membrane leak rate based on the second set of pressure signals;

h) calculating a leakage rate based on the baseline leak rate and the membrane leak rate; and

i) creating an alarm signal if the leakage rate exceeds a predefined value.

12. The system according to claim 11, wherein the alarm signal causes an auditory alarm.

13. The system according to claim 11, wherein the alarm signal causes a visual alarm.

14. The system according to claim 11, wherein the fluid is air.

15. The system according to claim 11, further comprising a memory unit for storing the pressure signals at the first set of predetermined timed intervals and storing the pressure signals at the second set of predetermined timed intervals.

16. The system according to claim 11, wherein the first chamber is disposed within a cassette wherein the membrane forms an exterior surface of the cassette.

17. A computer program product for use on a computer system for detecting a leakage rate of fluid through a membrane in a fluid flow control system having a first chamber and a second chamber, the membrane disposed between the first chamber and the second chamber, the second chamber having a connection to a pressure tank, the pressure tank having a fluid with a pressure, the connection defining a fluid path, the computer program product comprising a computer usable medium having computer readable program code thereon, the computer readable program code including:

program code for activating a valve controller for blocking the fluid path;

program code for adjusting the pressure of the fluid in the pressure tank;

program code for reading the pressure in the pressure tank while the fluid path is blocked;

program code for creating a pressure measurement at each of a first set of multiple timed intervals while the fluid path is blocked and after the pressure is adjusted;

program code for calculating a blocked pressure rate based on the pressure measurements in the pressure tank at the first set of multiple timed intervals;

program code for activating the valve controller unblocking the fluid path;

program code for reading the pressure within the pressure tank while the fluid path is unblocked;

program code for creating a pressure measurement at each of a second set of multiple timed intervals after the fluid path is unblocked;

program code for calculating an unblocked pressure rate based on the pressure measurements in the pressure tank at the second set of multiple timed intervals; and

program code for calculating a leakage rate based on the blocked pressure rate and the unblocked pressure rate.

18. The computer program product according to claim 17, further comprising

program code for causing an alarm when the leakage rate becomes greater than a predetermined threshold value.

19. The computer program product according to claim 17 further comprising:

program code for causing a alarm to be an auditory alarm.

20. The computer program product according to claim 17 further comprising program code for causing a alarm to be a visual alarm.