HK1141581A - Valve leakby diagnostics - Google Patents
Valve leakby diagnostics Download PDFInfo
- Publication number
- HK1141581A HK1141581A HK10107896.8A HK10107896A HK1141581A HK 1141581 A HK1141581 A HK 1141581A HK 10107896 A HK10107896 A HK 10107896A HK 1141581 A HK1141581 A HK 1141581A
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- Hong Kong
- Prior art keywords
- flow
- flow controller
- determining
- amount
- leakage
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Description
Background
Flow controllers are commonly used to control the flow of fluids in a process. A flow controller is typically comprised of a flow sensor, a flow control valve, and electronics (with optional software) to control the valve in response to the flow detected by the flow sensor. The flow sensor may be a thermal mass flow sensor, a coriolis mass flow sensor, a volumetric flow meter, or the like. Some flow controllers use valves that may not completely stop fluid flow when the valve is in a fully closed position. These types of flow controllers have a specified amount of fluid that may leak through the controller when the flow control valve is in an "off or fully closed position. The amount of fluid that leaks through the valve in these cases is referred to as the leak amount (leakby) and is defined as the amount of fluid that leaks through the flow controller when the controller is in the "off or fully closed position. Manufacturers using flow controllers can adjust their processes based on leak specification values. If the flow controller degrades or fails and the value of the leak increases above the specified value, the manufacturer may generate considerable production waste. Testing the amount of leakage of a flow controller currently requires removing or isolating the device from the process equipment and measuring the amount of leakage using off-line components of the measurement equipment. Shutting down the process equipment to isolate the flow controllers and connecting the off-line measurement equipment can result in significant down time of the process equipment. In capital-intensive plants, such as semiconductor plants, the cost of down time can be very expensive.
Disclosure of Invention
One aspect of the invention includes a method for determining an amount of leakage in a flow controller (100), comprising:
determining a zero drift (Qdrift) value for the flow controller (100);
determining a flow rate (Qflow) through the flow controller (100) when the flow control valve (100) is in a fully closed position;
an amount of leakage through the flow controller (100) is determined, wherein the amount of leakage is equal to Qflow-Qdrift.
Preferably, the method further comprises:
stopping flow through the flow controller (100) using a fluidic device;
determining an indicated flow through an internal flow sensor (102);
comparing the indicated flow rate with a previously stored flow rate to determine the zero drift (Qdrift) value.
Preferably, the method further comprises selecting the fluidic device from the group consisting of: a single external valve, a first external valve located at an inlet side of the flow controller and a second external valve located at an outlet side of the flow controller, a single integrated valve, a first integrated valve located at an inlet side of the flow controller and a second integrated valve located at an outlet side of the flow controller, a pump, a pressure reducing valve.
Preferably, the method further comprises manually controlling the fluidic device.
Preferably, the method further comprises electrically controlling the fluidic device.
Preferably, the method further comprises:
waiting a predetermined time before determining an indicated flow rate through the internal flow sensor (102).
Preferably, determining the flow rate (Qflow) through the flow controller (100) further comprises:
allowing flow through the flow controller (100);
setting the flow controller (100) to a fully closed position;
an indicated flow rate through the internal flow sensor (102) is determined, and the indicated flow rate is equalized with a flow rate (Qflow) through the flow controller (100).
Preferably, the method further comprises:
connecting an external device (110) to the flow controller (100) and operating the flow controller (100) using the external device (110) to determine an amount of leakage.
Preferably, the method further comprises:
comparing the leak amount to a threshold;
establishing an error condition when the leak amount is greater than the threshold.
Another aspect of the present invention includes a flow controller comprising:
a flow sensor that generates a signal indicative of a flow rate of the substance flowing through the flow controller;
a flow control valve;
a display;
an input device;
an electronic device coupled to the flow sensor, the flow control valve, the display, and the input device, and configured to adjust the flow control valve in response to a signal indicative of a material flow such that a set flow of material through the flow controller is maintained, and wherein the electronic device is configured to determine a value of a leak amount by determining a zero drift (Qdrift) value of the flow controller, determining a flow rate (Qflow) through the flow controller when the flow controller is in a fully closed position, and determining a leak amount through the flow controller, the leak amount being equal to Qflow-Qdrift.
Preferably, at least one shut-off valve is configured to completely stop the flow of material through the flow controller.
Preferably, the at least one shut-off valve is electrically controlled.
Preferably, the flow sensor is selected from the group consisting of: coriolis mass flow sensors, single line design thermal mass flow sensors, two line design thermal mass flow sensors, volumetric flowmeters.
Another aspect of the invention includes a test system comprising:
a flow controller having an input/output port;
at least one shut-off valve fluidly coupled to the flow controller and configured to stop the flow of the substance through the flow controller;
a device coupled to an input/output port of the flow controller, the device configured to determine a value of a leak amount by determining a zero drift (Qdrift) value of the flow controller, determining a flow rate (Qflow) through the flow controller when the flow controller is in a fully closed position, and determining a leak amount through the flow controller, the leak amount equal to Qflow-Qdrift.
Preferably, the at least one shut-off valve is electrically controlled.
Preferably, the device is selected from the group consisting of: portable computer, testing device, remote processor, network computer.
Preferably, the flow controller comprises a flow sensor selected from the group consisting of: coriolis mass flow sensors, single line design thermal mass flow sensors, two line design thermal mass flow sensors, volumetric flowmeters.
Another aspect of the invention includes a test apparatus comprising:
an electronic device configured to couple with an input/output port of a flow controller, the electronic device configured to determine a value of a leak amount by determining a zero drift (Qdrift) value of the flow controller, determining a flow rate (Qflow) through the flow controller when the flow controller is in a fully closed position, and determining a leak amount through the flow controller, the leak amount being equal to Qflow-Qdrift.
Drawings
Fig. 1 is a block diagram of a flow controller 100 in an exemplary embodiment of the invention.
Fig. 2a is a schematic diagram of a flow controller 100 installed in a process tool using an external valve in an exemplary embodiment of the invention.
Fig. 2b is a schematic illustration of the flow controller 100 installed in a process tool using a valve coupled to or integral with the flow controller 100 in an exemplary embodiment of the invention.
Fig. 3 is a flow chart for determining an amount of leakage through the flow controller 100 in an exemplary embodiment of the invention.
Fig. 4 is a flowchart illustrating steps for determining Qdrift in step 302 in an exemplary embodiment of the invention.
Fig. 5 is a flowchart illustrating steps for determining the flow rate (Qflow) through the flow controller in step 304 in an exemplary embodiment of the invention.
Detailed Description
Fig. 1-5 and the following description depict specific examples to teach those skilled in the art how to make and use the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate numerous variations from these examples that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific examples described below, but only by the claims and their equivalents.
Fig. 1 is a block diagram of a flow controller 100 in an exemplary embodiment of the invention. The flow controller 100 includes a flow sensor 102, electronics 104, an input/output port 108, and a flow control valve 106. The flow sensor 102 and the flow control valve 106 are coupled to the electronics 104. The electronic device 104 may be connected to an external device 110 using an input/output port 108. The external device 110 may be used to install the flow controller 100 or to run diagnostics of the flow controller 100. The external device 110 may be a portable computer, a test device, a remote processor, a network computer, or the like. In operation, the flow sensor 102 generates a signal indicative of the flow of the substance through the flow controller 100. The electronics 104 detect the flow signal generated by the flow sensor 102. The electronics 104 adjust the flow control valve 106 in response to a signal from the flow sensor 102 to maintain the flow of the substance through the flow controller 100. In an exemplary embodiment of the invention, the flow controller may have a plurality of optional input devices 114, such as an analog voltage input that allows a user to set the flow control valve, a keypad, or another analog voltage input that allows a user to set the flow controller set point command, and a display that allows a user to read the flow through the flow controller without connecting an external device to the input/output port 108.
The flow sensor 102 may be a single wire design thermal mass flow meter, a two wire design thermal mass flow meter, a coriolis flow meter, a volumetric flow meter, or any other type of flow meter. The flow control valve may be a needle valve, a butterfly valve, a solenoid valve, or any other type of valve that may be adjusted to a plurality of different positions between the closed and open positions.
Fig. 2a is a schematic diagram of a flow controller 100 installed in a process tool using an external valve in an exemplary embodiment of the invention. Tube 206 couples valve 202 to process equipment (not shown). A pipe 208 couples the valve 202 with the input side of the flow controller 100. A tube 210 couples the output side of the flow controller 100 with the valve 204. Pipe 212 connects valve 204 to a plurality of process equipment (not shown). In an exemplary embodiment of the invention, valves 202 and 204 are external shut-off or block valves that can be used to isolate flow controller 100 from the process tool by completely blocking the flow of material through flow controller 100. In other exemplary embodiments of the invention, only one external shut-off valve may be used and placed in the position of valve 202 or in the position of valve 204. During normal operation, valves 202 and 204 are in an open position that allows flow controller 100 to control the flow of material from pipe 206 to pipe 212. In an exemplary embodiment of the invention, the external valves 202 and 204 are manual valves and are manually operated by a user in a process that is used to determine a value for the amount of leakage. In another exemplary embodiment of the invention, the external valves 202 and 204 are electrically controlled and operated by the flow controller 100 or the external device 110 in a process used to determine the amount of leakage. In another exemplary embodiment of the present invention, as shown in FIG. 2b, valves 202 and 204 may be directly connected to or integrally formed with flow controller 100.
Fig. 3 is a flow chart for determining an amount of leakage through the flow controller 100 in an exemplary embodiment of the invention. In step 302, a zero drift (Qdrift) value for the flow controller is determined. In step 304, the flow rate through the flow controller (Qflow) is determined. In step 306, the amount of leakage through the flow controller is calculated as Qflow-Qdrift. In optional step 308, the amount of leakage through the flow controller is compared to a threshold value. If the amount of leakage is greater than the threshold, an error condition is established in step 310. In an exemplary embodiment of the invention, the amount of leakage may be displayed or reported without comparison to a threshold.
Fig. 4 is a flowchart illustrating steps for determining Qdrift in step 302 in an exemplary embodiment of the invention. In step 402, flow through the flow controller 100 is stopped. The flow can be stopped in a number of different ways. One way is to close a single external shut-off valve to prevent flow into or out of the flow controller 100. In another exemplary embodiment of the invention, two external or integrated valves (202 and 204), one on each side of the flow controller 100, may be used to stop the flow of material through the flow controller 100. In other exemplary embodiments of the invention, the run pump that drives the flow of fluid through the flow controller 100 may be turned off. External valves, integrated valves, pumps, pressure relief devices, or other devices for completely closing the flow of material through the flow controller 100 are considered fluidic devices. After the pump is shut off or the valve is shut off, it may take some time for flow through the flow controller 100 to stop completely. Even when valves are employed on each side of the flow controller 100, it may take some time for flow through the flow controller 100 to stop after both valves are closed. In an exemplary embodiment of the invention, a predetermined time is allowed to elapse to ensure that flow through the flow controller 100 is stopped.
Once the flow of the substance through the flow controller 100 has stopped, a zero drift (Qdrift) of the flow sensor 102 is determined in step 404. The zero drift (Qdrift) is the magnitude of the fluid flow measured by the flow sensor 102 during the no-flow state relative to the last zero. During a known no-flow condition by the flow sensor 102, a zero point is established that equates the indicated flow signal from the flow sensor 102 to zero flow. The zero-point drift (Qdrift) is the amount of zero-point drift compared to when the mass flow sensor 102 is in a no-flow state. The zero drift measurement depends on the environmental conditions, such as temperature. When the last zero flow zero is determined, large temperature changes in the flow controller 100 compared to the temperature of the device can result in large zero drift values. The zero point drift may be determined from a single data point or may represent a plurality of different samples. Once the current zero drift (Qdrift) is determined, a new set point for zero flow can be established by re-equating the current flow signal to zero flow. In an exemplary embodiment of the invention, an error flag or error condition may be established if the zero drift value is greater than a threshold value.
Fig. 5 is a flowchart illustrating steps for determining the flow rate (Qflow) through the flow controller in step 304 in an exemplary embodiment of the invention. In step 502, the flow controller 100 is reengaged into the process system by opening the valve that was closed in step 302 or by opening any pump that was closed in step 302. In step 504, the flow controller 100 is set to an "off" or fully closed position. By setting the flow controller 100 to the "off" position, any flow through the flow controller 100 is caused by leakage through the flow control valve 106. In step 506, the flow rate (Qflow) through the flow sensor 102 is measured. The Qflow may be determined from a single data point, or may represent multiple different samples. Once Qflow is determined, the leakage through the flow controller 100 is calculated as Qflow-Qdrift. Most flow controllers have a specified value for the amount of leakage. In some exemplary embodiments of the invention, an error condition may be established if the calculated leak amount is greater than the allowable leak amount. In other exemplary embodiments of the invention, the calculated leak amount is reported to the user.
In an exemplary embodiment of the invention, the software or firmware for determining the value of the leak may be run by internal electronics 104 within the flow controller 100. In another exemplary embodiment of the invention, an external device 110, such as a computer, may be connected to the input/output port 108 and used to determine the value of the leak by running software or firmware connected to the flow controller 100. When an external device is used to determine the amount of leakage, the external device, the flow controller 100, and at least one valve for stopping the flow of material through the flow controller may be considered a test system. The external device 110 may be considered a test device.
Claims (18)
1. A method for determining an amount of leakage in a flow controller (100), comprising:
determining a zero drift (Qdrift) value for the flow controller (100);
determining a flow rate (Qflow) through the flow controller (100) when the flow control valve (100) is in a fully closed position;
an amount of leakage through the flow controller (100) is determined, wherein the amount of leakage is equal to Qflow-Qdrift.
2. The method for determining an amount of leakage of claim 1, wherein determining a zero drift (Qdrift) value further comprises:
stopping flow through the flow controller (100) using a fluidic device;
determining an indicated flow through an internal flow sensor (102);
comparing the indicated flow rate with a previously stored flow rate to determine the zero drift (Qdrift) value.
3. The method of determining an amount of leakage of claim 2, wherein the fluid device is selected from the group consisting of: a single external valve, a first external valve located at an inlet side of the flow controller and a second external valve located at an outlet side of the flow controller, a single integrated valve, a first integrated valve located at an inlet side of the flow controller and a second integrated valve located at an outlet side of the flow controller, a pump, a pressure reducing valve.
4. The method of determining an amount of leakage of claim 2, wherein the fluid device is manually controlled.
5. The method of determining an amount of leakage of claim 2, wherein the fluid device is electrically controlled.
6. The method for determining an amount of leakage of claim 2, further comprising:
waiting a predetermined time before determining an indicated flow rate through the internal flow sensor (102).
7. The method for determining an amount of leakage of claim 1, wherein determining the flow rate (Qflow) through the flow controller (100) further comprises:
allowing flow through the flow controller (100);
setting the flow controller (100) to a fully closed position;
an indicated flow rate through the internal flow sensor (102) is determined, and the indicated flow rate is equalized with a flow rate (Qflow) through the flow controller (100).
8. The method for determining an amount of leakage of claim 1, further comprising:
connecting an external device (110) to the flow controller (100) and operating the flow controller (100) using the external device (110) to determine an amount of leakage.
9. The method for determining an amount of leakage of claim 1, further comprising:
comparing the leak amount to a threshold;
establishing an error condition when the leak amount is greater than the threshold.
10. A flow controller comprising:
a flow sensor that generates a signal indicative of a flow rate of the substance flowing through the flow controller;
a flow control valve;
a display;
an input device;
an electronic device coupled to the flow sensor, the flow control valve, the display, and the input device, and configured to adjust the flow control valve in response to a signal indicative of a material flow such that a set flow of material through the flow controller is maintained, and wherein the electronic device is configured to determine a value of a leak amount by determining a zero drift (Qdrift) value of the flow controller, determining a flow rate (Qflow) through the flow controller when the flow controller is in a fully closed position, and determining a leak amount through the flow controller, the leak amount being equal to Qflow-Qdrift.
11. The flow controller of claim 10, further comprising:
at least one shut-off valve configured to completely stop the flow of material through the flow controller.
12. The flow controller of claim 11, wherein the at least one shut-off valve is electrically controlled.
13. The flow controller of claim 10, wherein the flow sensor is selected from the group consisting of: coriolis mass flow sensors, single line design thermal mass flow sensors, two line design thermal mass flow sensors, volumetric flowmeters.
14. A test system, comprising:
a flow controller having an input/output port;
at least one shut-off valve fluidly coupled to the flow controller and configured to stop the flow of the substance through the flow controller;
a device coupled to an input/output port of the flow controller, the device configured to determine a value of a leak by determining a zero drift (Qdrift) value of the flow controller, determining a flow rate (Qflow) through the flow controller when the flow controller is in a fully closed position, and determining a leak through the flow controller, the leak being equal to Qflow-Qdrift.
15. The flow controller of claim 14, wherein the at least one shut-off valve is electrically controlled.
16. The flow controller of claim 14, wherein said means is selected from the group consisting of: portable computer, testing device, remote processor, network computer.
17. The flow controller of claim 14, wherein the flow controller comprises a flow sensor selected from the group consisting of: coriolis mass flow sensors, single line design thermal mass flow sensors, two line design thermal mass flow sensors, volumetric flowmeters.
18. A test apparatus, comprising:
an electronic device configured to couple with an input/output port of a flow controller, the electronic device configured to determine a value of an amount of leakage by determining a zero drift (Qdrift) value of the flow controller, determining a flow rate (Qflow) through the flow controller when the flow controller is in a fully closed position, and determining an amount of leakage through the flow controller, the amount of leakage being equal to Qflow-Qdrift.
Publications (1)
| Publication Number | Publication Date |
|---|---|
| HK1141581A true HK1141581A (en) | 2010-11-12 |
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