Valve isolation system

• US 6,764,059 B2
• Filed: 09/27/2002
• Issued: 07/20/2004
• Est. Priority Date: 09/27/2002
• Status: Active Grant

• Current Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Original Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Inventors: Cleereman, Douglas P., Rygiewicz, Dennis J., Bucher, Carmen F., Johnson, Jonathan B.
• Primary Examiner(s): Bastianelli, John
• Application Number:
  US10/260,097
• Publication Number:
  US 20040061088A1
• Time in Patent Office: 662 Days
• Field of Search: 257/129.04, 257/129.15, 137/552, 137/557
• US Class Current: 251/129.04
• CPC Class Codes: F15B 19/005 Fault detection or monitoring
• CPC Class Codes: F15B 20/008 Valve failure
• CPC Class Codes: Y10T 137/7908 Weight biased

Abstract

A system and method for controlling and monitoring operation of a valve are disclosed. The system includes an actuator and a switch that, upon being actuated, provides a control signal to the actuator designed to cause the valve to change from a first state to a second state. The system further includes a sensor positioned downstream of the valve, an indicator, and a detection device coupled at least indirectly to the switch, the sensor and the indicator. When not detecting a sensor failure, the detection device allows the indicator to indicate that the valve has changed its state in response to the switch being actuated when the sensor indicates that the valve has so changed. Upon detecting a sensor failure, the detection device prevents the indicator from indicating that the valve has changed its state in response to the switch being actuated.

Claims

1. A system for controlling and monitoring the operation of a valve, the system comprising:

a valve actuator;

a switch that, upon being actuated, provides a control signal to the valve actuator designed to cause the valve to change from a first valve state to a second valve state;

a first sensor positioned downstream of the valve;

a first output indicator; and

a sensor failure detecting device coupled at least indirectly to the switch, the first sensor and the first output indicator,

wherein, when not detecting a sensor failure, the sensor failure detecting device allows the first output indicator to indicate that the valve has changed from the first valve state to the second valve state in response to the switch being actuated when the sensor indicates that the valve has so changed; and

wherein, upon detecting a sensor failure, the sensor failure detecting device prevents the output indicator from indicating that the valve has changed from the first valve state to the second valve state in response to the switch being actuated.

2. The system of claim 1, wherein the first output indicator is one of an indicator light and an alarm sound, wherein the switch is one of an RLS switch, a push-button switch, and a trigger, wherein the valve actuator is a solenoid, and wherein in the first valve state the valve is open and in the second valve state the valve is closed.

3. The system of claim 1 wherein, upon detecting a sensor failure, at least one of the sensor failure detecting device and the first output indicator provides information indicating that the sensor failure has occurred, and

wherein, the sensor failure detecting device detects that a sensor failure has occurred by detecting at least one of an improper sensor state when the switch is actuated and a failure of the sensor to switch in its state after the switch is actuated.

4. The system of claim 3, further comprising a second sensor positioned downstream of the valve and wherein, upon detecting a sensor failure, at least one of the sensor failure detecting device and the first output indicator provides information indicating an identity of the sensor that has failed.

5. The system of claim 2, further comprising a second sensor and wherein, absent a sensor failure, each of the first and second sensors switches to a first sensor state when fluid pressure sensed by the respective sensor is above a respective threshold, and switches to a second sensor state when the fluid pressure sensed by the respective sensor is below the respective threshold.

6. The system of claim 5, wherein each of the first and second sensors includes first and second contacts, wherein when each respective sensor is in its first sensor state, its respective first contact is closed and its respective second contact is open, and when each respective sensor is in its second state, its respective first contact is open and its respective second contact is closed.

7. The system of claim 6, wherein the sensor failure detecting device includes a first coil that is energized upon the switch being actuated if the first contacts of both of the first and second sensors are closed, and wherein the sensor failure detecting device further includes a circuit component that keeps the first coil energized even though the first contacts of the first and second pressure sensors are subsequently opened.

8. The system of claim 7 wherein, absent a sensor failure, the respective first contacts of the first and second sensors are closed when the pressure sensed by the first and second sensors is above their respective thresholds, the respective first contacts are open when the pressure sensed by the respective sensors is below their respective thresholds, the respective second contacts are open when the pressure sensed by the respective sensors is above their respective thresholds, and the respective second contacts are closed when the pressure sensed by the respective sensors is below their respective thresholds.

9. The system of claim 8, further comprising a second output indicator that is coupled at least indirectly to the sensor failure detecting device, and a second coil that is energized that is energized upon the switch being actuated if the first contacts of both of the first and second sensors are closed, and wherein the sensor failure detecting device further keeps the second coil energized even though the first contacts of the first and second sensors are subsequently opened.

10. The system of claim 9, wherein upon the energizing of the first coil and closing of the second contact of the first sensor, the first output indicator indicates that the valve is in the second valve state, and wherein upon the energizing of the second coil and closing of the second contact of the second sensor, the second output indicator indicates that the valve is in the second state.

11. The system of claim 10 wherein, when the first sensor is welded so that its first contact remains closed, the first output indicator does not indicate that the valve is in the second valve state despite the energizing of the first coil, and thus a first indication is provided that the first sensor has failed;

wherein, when the second sensor is welded so that its first contact remains closed, the second output indicator does not indicate that the valve is in the second valve state despite the energizing of the second coil, and thus a second indication is provided that the second sensor has failed; and

wherein, when at least one of the first and second sensors is welded so that its respective second contact remains closed, neither of the first and second coils is energized and neither of the first and second output indicators indicates that the valve is in the second valve state, and thus an indication is provided that one of the sensors has failed.

12. The system of claim 8, wherein the sensor failure detecting device further includes first and second safety relay circuits, wherein each of the first and second sensors includes a respective third contact that is closed when the pressure sensed by the respective sensor is above its respective threshold and is open when the pressure sensed by the respective sensor is below its respective threshold, and wherein the first safety relay circuit is coupled to the second and third contacts of the first sensor and the second safety relay circuit is coupled to the second and third contacts of the second sensor.

13. The system of claim 12, wherein the first and second safety relay circuits are powered when the first coil is energized, and wherein each of the first and second safety relay circuits includes a respective power indicator that provides a respective power indication when the respective safety relay circuit is powered.

14. The system of claim 13, wherein each of the first and second safety relay circuits includes a respective output indicator that provides a respective output indication when the respective safety relay circuit is energized;

wherein the first and second safety relay circuits are respectively energized when the respective second contacts coupled to the respective relay circuits are closed, the respective third contacts coupled to the respective relay circuits are opened, and the respective relay circuits are powered; and

wherein the output indicator indicates that the valve is in the second state when both of the first and second safety relays are energized.

15. The system of claim 14, wherein when any of the first and third contacts of the first sensor are welded closed, the output indicator of the first safety relay cannot be energized despite the safety relay being powered, and consequently the output indicator does not provide its output indication, thus indicating that the first sensor has failed;

and

wherein when any of the first and third contacts of the second sensor are welded closed, the output indicator of the second safety relay cannot be energized despite the safety relay being powered, and consequently the output indicator does not provide its output indication, thus indicating that the second sensor has failed.

16. The system of claim 15, wherein when one of the second contacts of the first and second sensors is welded closed, the first coil cannot be energized, and consequently neither of the power indicators of the first and safety relays provides the power indication, thus indicating a failure of at least one of the sensors;

and

wherein when any of the first, second and third contacts is welded closed, at least one of the first and second safety relays cannot be energized and consequently the first output indicator does not indicate that the valve is in the second state.

17. The system of claim 1, further comprising a plurality of additional switches, a plurality of additional output indicators, and a safety relay circuit;

wherein each switch is coupled in series with a respective one of the output indicators;

wherein each switch and output indicator corresponds to a respective access panel by which it is possible to gain access to the valve; and

wherein, when any of the switches is actuated to a respective off state, the safety relay circuit becomes de-energized, which causes the control signal to be provided to the valve actuator.

18. A system comprising:

a flow-governing device;

an actuator for controlling a status of the flow-governing device;

first and second sensors that operate to sense the status of the flow-governing device;

means for receiving commands to change the status of the flow-governing device, for providing a control signal to the actuator in response to the received commands, for receiving signals from the sensors, for detecting when a sensor malfunction has occurred, and for providing at least one output indication indicative of the sensor malfunction when the sensor malfunction has occurred.

19. The system of claim 18, wherein the means additionally is for turning on an indicator light when the means receives a command to switch off the flow-governing device and the means does not detect any sensor malfunction, and wherein the at least one output indication is an absence of the indicator light being turned on when the means receives the command to switch off the flow-governing device.

20. A method of monitoring whether a valve has been shut off in response to a command, the method comprising:

causing at least one switching element of an electric circuit to change a state in response to the command;

energizing a coil in response to the changing of the state of the at least one switching element, wherein the energizing of the coil only occurs if a sensor component is in a first position indicating that the valve has not been shut off;

energizing an indicator light in response to the energizing of the coil, wherein the energizing of the indicator light only occurs if the sensor component switches, subsequent to the energizing of the coil, from the first position to a second position indicating that the valve has been shut off.