WO2005119108A1

WO2005119108A1 - Apparatus and method for detecting and isolating a rupture in a fluid conveying system

Info

Publication number: WO2005119108A1
Application number: PCT/US2005/019303
Authority: WO
Inventors: Alistair R. W. Baird; Charles N. Chatterley; Horace Maxwell
Original assignee: Tyco Flow Control, Inc.
Priority date: 2004-06-02
Filing date: 2005-06-02
Publication date: 2005-12-15

Abstract

Apparatus and method for detecting a rupture in a fluid conveying system based on a decrease pressure and increases in flow rate in the fluid conveying system. When a rupture occurs in the fluid conveying system, the pressure of the fluid conveying system decreases and flow increases near the point of rupture. The rupture detecting system mechanically activates and closes an isolation valve when predetermined pressure and flow rates in the fluid conveying system are exceeded. The rupture detecting system includes a flow sense unit having a dual cartridge/spool/biasing device assembly and a diaphragm assembly, and a pressure sense unit having a single cartridge/piston/biasing device and a diaphragm assembly interconnected with a conventional isolation valve.

Description

APPARATUS AND METHOD FOR DETECTING AND ISOLATING A RUPTURE IN A FLUID CONVEYING SYSTEM

RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of US Provisional 60/576,256, entitled SYSTEM AND METHOD FOR ISOLATING A RUPTURE IN A FLUID CONVEYING SYSTEM, filed June 2, 2004, which is hereby incorporated by reference herein.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to a system and method for automatically and mechanically isolating ruptures in fluid conveying systems without the need of electrical or electronic components for the determination of certain valves to be shutoff in the fluid conveying system and the shutoff time sequencing of such valves. In particular, the present invention relates to the independent, autonomous, mechanical actuation of the shutoff valves without the prior knowledge to the status of other shutoff valves within the fluid conveying system.

[0003] Fluid conveying systems often include closed-loop circuits with branches configured typically of piping or tubing through which fluid flow is controlled using one or more valves. A few examples of such fluid conveying systems include systems that distribute cooling fluid through energy generation or energy management systems, and an automated fire control system found in buildings and aboard sea vessels. An automated fire control system, for example, can be compromised by ruptures, which reduce the pressure at sprinkler heads such that the sprinkler becomes ineffective. Such a case can occur say in naval vessel which is damaged by hostile fire, or in non military applications where piping systems can be damaged by gas explosions earthquakes etc. [0004] A further example of a fluid conveying system that require a rupture isolation mechanism is a pipe line for conveying oil, water, fuel, liquid nitrogen and other incompressible fluid as well as compressible fluids, such as air, hydrogen, helium, and propane.

[0005] A gross rupture event is characterized by a reduction in pressure and an increase in flow in all paths leading to the rupture. The extent of the pressure drop is determined by the ability of the pumps in the system to supply the flow demand, and the resistance of the flow path between the pump and the rupture. The highest flows are measured in the paths that offer the least resistance. In a multi path system during a rupture this may result flow in the direction opposite to that which would be considered normal.

[0006] Current fluid conveying technology use valves that are actuated by electric, pneumatic or hydraulic actuators that respond to control signals generated from a remote controller. Rupture or leak detection in these fluid conveying systems is based primarily on sophisticated software algorithms running on electronic processors in electronic communication with sensing systems that monitor a plurality of sensors and valves. Examples of two such software algorithms are hydraulic flow balance algorithms to detect fluid loss within a piping system and acoustic signal characterization to determine leak conditions. Flow balance techniques utilize flow sensors distributed throughout the piping system to perform fluid mass balance evaluations within selected piping sections. Acoustic signal characterization techniques also distribute sensors throughout a piping system to "listen" for signals that provide an indication of a leak. These techniques and others rely on electrical power for communication between remote sensors and a central processor for identifying and effectively sealing a leak or rupture.

[0007] None of the current state of the art fluid conveying systems can adequately function without a stable electrical energy supply. Without such power the status of the sensors and valves cannot be communicated to the processor for analysis. In the situation where electrical power is interrupted at the processor, the processor cannot perform the sophisticated software algorithms to determine whether a shutoff valve should be activated. As a result, a rupture may not be isolated and fluid pressure may not be restored to portions of the fluid conveying system that are intact to regain normal operating capabilities.

[0008] A more effective technique is needed for detecting and isolating ruptures automatically without the need of electric power or electronic processing of valve status in fluid conveying systems.

SUMMARY OF THE INVENTION

[0009] The present invention monitors the flow rate and the flow direction by means of a flow sense unit, and the lowest fluid conveying system pressure at a commercially available mechanically actuated isolation valve by means of a pressure sense unit. The flow sense unit includes a dual cartridge/spool assembly, and a flow sense diaphragm assembly. The pressure sense unit includes a single cartridge/spool, pressure sense diaphragm assembly.

[0010] When a rupture occurs in the fluid conveying system, the pressure of the system decreases and flow increases near the point of rupture. Based upon these two characteristics, the present invention mechanically activates the rupture isolation valve when two conditions are met:

[0011] 1. fluid conveying system flow exceeds a predetermined flow rate and

[0012] 2. fluid conveying system pressure is below a predetermined minimum pressure.

[0013] When both conditions are met the highest available line pressure, Pi or P2, is directed through both the flow sense unit and pressure sense unit and mechanically closes the isolation valve. If either condition 1 or condition 2 are not met, the present invention exhausts fluid into the atmosphere and the isolation valve remains open.

[0014] The present invention operates without electric power thereby avoiding costly electronic components, including computer processor, that are susceptible to failure due to electric power interruption and damage caused by an explosive.

[0015] Further, the present invention is sufficiently robust to operate after a catastrophic event, such as an explosion.

[0016] The present invention can be implemented into multi- valve multi-path systems. Therefore, eliminate the need to interact with other similar valves in the system, which may manipulate the operating conditions that the valve sees . The present invention can detect and isolate ruptures within a multi-path fluid conveying system having a plurality of isolation valves. The present invention (a) independently senses pressure upstream (PI) and downstream (P2) at or near each isolation valve; (b) independently determines at each isolation valve whether a rupture has occurred in its fluid conveying path based on Step (a) pressure measurements; (c) initiates a variable time delayed closing of each isolation valve that detects a rupture in its fluid conveying path, wherein time delays vary for each isolation valve; and (d) reopens each isolation valve when conditions indicate that the rupture condition has passed.

[0017] The present invention can be coupled to a speed control to add a timing mechanism to delay the response of the present invention to control the closure of the isolation valves in a looped network or series of isolation valves. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0018] Figure 1 is a pictorial illustration of one embodiment of the present invention adapted to a conventional isolation valve installed in a fluid conveying system;

[0019] Figures 2A-2C are block diagrams illustrating the process of the closure and reopening of an isolation valve adapted to the present invention of FIG. 1;

[0020] Figure 3 are cross-section views of the flow sense unit and the pressure sense unit illustrating the flow path and direction of the system fluids communicated to and through the present invention of Figure 1;

[0021] Figure 4 is a 2D cross-section view of the flow sense unit of the present invention of Figures 1 and 3;

[0022] Figure 5 is a 2D cross-section view of the pressure sense unit of the present invention of Figures 1 and 3;

[0023] Figures 6A and 6B are pictorial illustrations of the present invention of Figure 1 showing the piping and tubing further defining the flow circuitry of the present invention of FIG. 1;

[0024] Figure 7 is a prospective cross-section view of one embodiment of the fluid transfer switch of the present invention;

[0025] Figure 8 are 2D cross-section views of one embodiment of the LP and HP cartridges of the present invention comparing distances of the fluid transfer port center-lines;

[0026] Figure 9 is a 2D cross-section view of an alternative embodiment of the present invention including a speed control valve;

[0027] Figure 9 is a 2D cross-section view of another alternative embodiment of the present invention including a pneumatic actuator; [0028] Figures 11A-11C are pictorial representatives of fluid schematics of the present invention illustrating the flow path through the flow sense unit and pressure sense unit;

[0029] Figures 12A-12C are pictorial representatives of a plurality of isolation valves adapted with the present invention implemented in a fluid conveying system network; and

[0030] Figures 13A-13H are pictorial views of an alternative embodiment of the flow sense unit for the present invention of Figure 1.

DETAILED DESCRIPTION OF THE INVENTION

[0031] Now referring to FIG. 1, the present invention 10 includes a bi-directional rupture detecting apparatus mounted on a commercially available mechanically actuated isolation valve 12, which operates regardless of the flow direction through the isolation valve 12, installed in a fluid conveying system 14. The present invention 10 actuates the isolation valve to or causes the isolation valve 12 to close when the fluid flow rate and flow pressure conditions in the fluid conveying system 14 indicates a rupture in the fluid conveying system 14. The present invention 10 includes a flow sense unit 16 and a pressure sense unit 18.

[0032] The present invention 10 is designed to be compatible with the fluid conveying system specifications defined by the customer and conventional isolation valves. In this invention, isolation valve is being used in its generic sense, that is, indicating a fluid control device or component, diaphragm or non-diaphragm isolation valve (such as a butterfly valve or a knife-edge valve), and these terms will be used interchangeably through the specification and claims. A diaphragm or non-diaphragm isolation valve can be used in the present invention. For illustration purposes, a diaphragm isolation valve will be used as an example and is referred to as an isolation valve, however it is not intended to limit the present invention. A non-diaphragm isolation valve is presented as an alternative embodiment and is discussed in detail below.

[0033] A rupture in the fluid conveying system 14 can be detected by a predetermined increase in fluid conveying system 14 flow rate (which can be converted in a pressure differential increase) and an overall drop in the fluid conveying system 14 pressure. The present invention employs a pressure differential and pressure forces, respectively, to close an isolation valve 12 that is in fluid communication with the present invention.

[0034] Now turning to FIGS. 2A-2C that illustrate the process performed by the present invention 10 to evaluate certain fluid conditions in the fluid conveying system 14 to accurately and timely shutdown and reopen an isolation valve 12 by mechanical means. The logic process of the present invention 10 to close and reopen an isolation valve 12 includes the following steps (see FIG. 2A) :

[0035] Step A. Sensing the fluid conveying system 14 upstream pressure (PI) and downstream pressure (P2) at the isolation valve 12. In this invention, downstream pressure is also referred to as system minimum pressure, system pressure, or pressure, and these terms will be used interchangeably through the specification and claims.

[0036] Step B. Determining whether the fluid conveying system flow is greater than a predetermined flow (threshold).

[0037] Step C. Determining whether the fluid conveying system minimum pressure (PI or P2 ) is below a predetermined pressure (threshold).

[0038] Step D. Closing the isolation valve (no flow through the isolation valve 12) in response to meeting the affirmative conditions set forth in steps B and C.

[0039] After the isolation valve is closed, the system integrity will eventually be restored resulting in the system pressure being increased and the flow rate decreasing. The present invention continuously monitors the status of the fluid conveying system for normal operating conditions and will open the isolation valve when such conditions exist by the following steps (see FIG. 2B):

[0040] 1. Determining whether PI equals P2;

[0041] 2. Determining whether system pressure is greater than the required pressure to hold the isolation valve closed; or

[0042] 3. Determining whether the flow rate is below the threshold.

[0043] If any of these conditions exist, then the isolation valve is reopened.

[0044] Also as the isolation valve is closing (a transient state), there is a possibility that the fluid integrity of the system will be restored resulting in the system pressure being increased and the flow rate decreasing. The present invention monitors the fluid conveying system by the following steps (See FIG. 2C) :

[0045] 1. Determine whether the fluid conveying system flow is less than the predetermine threshold flow rate. If yes, then reopen the isolation valve. If no, do nothing.

[0046] 2. Determine whether the fluid conveying system minimum pressure is greater than the predetermined threshold pressure. If yes, then reopen the isolation valve. If no, do nothing.

[0047] 3. The present invention will continue to monitor the transient state of the isolation valve until the isolation valve is fully closed. Then the logic process steps of FIG. 2B will control.

[0048] Now referring to FIGS. 3, 4, 5, 6A, and 6B, are exemplary illustrations of one embodiment of the present invention that includes a flow sense unit 16 and pressure sensor unit 18 interconnected by pipes and tubes 36 for fluid communication within the present invention 10 and between the isolation valve 12.

[0049] The flow sense unit 16 includes a diaphragm assembly 20 that senses the pressure differential (P2-P1) in the fluid conveying system 14 as the fluid passes through in the isolation valve 12, where P2 is the pressure downstream of the isolation valve 12 and PI is the pressure upstream of the isolation valve 12. The diaphragm assembly 20 is of conventional design including a PI chamber 22 and P2 chamber 24 separated by diaphragm plates 26. A piston bracket 28 is attached to the diaphragm plates 26 for the activation of the flow sense unit 16 (discussed in detail below) to transfer PI and P2 fluid to appropriate entrance and exit ports of the Low Pressure (LP) fluid transfer switch 32 and High Pressure (HP) fluid transfer switch 34.

[0050] The piston bracket 28 is conventionally attached to the diaphragm plates 26 by means of, for example, bolts, screws, or a weld. As the diaphragm plates 26 move forward and back in response to sufficient differential of pressure (P2-P1), the piston plate 28 will also translate along a substantially longitudinal path.

[0051] The flow sense unit 16 further includes a housing 30 to encase an LP fluid transfer switch 32, an HP fluid transfer switch 34, and a series of fluid pipes or tubes 36 for fluid communication between the fluid conveying system 14, the flow sense unit 16, the pressure sense unit 18, and the isolation valve 12. The LP fluid transfer switch 32 and HP fluid transfer switch 34 include entrance and exit ports 44, 46, 48A, 48B, 50, 52, 54, 56A, 56B, and 58 (FIG. 4).

[0052] As illustrated in FIG. 6B, the housing 30 includes a P2 inlet 38, Pi inlet 40, and an isolation valve outlet 42 includes a plurality of fluid inlet and outlet ports to provide fluid passageways or correctors for the conveyance of certain fluids. [0053] Now returning to FIG. 4, each fluid transfer switch 43, 34 includes a stem 60 conventionally connected to the piston plate 28, a substantially cylindrical spool 62, a pair of opposing biasing devices 64, and a substantially cylindrical cartridge (LP cartridge 66, HP cartridge 68).

[0054] Now referring to FIG. 7, the spool 62 includes a fluid transfer channel 70 of a generally an "H" shaped (or "U" shape as illustrated in FIG. 4) configuration. Any configuration of the channel 70 that routes fluid a predetermined distance is sufficient. For example, channel 70 has at least two ports that alternate being entrance and exit ports depending on the longitudinal position of the spool 62 within cartridges 66, 68. The spool fluid transfer channel ports 72 are substantially aligned with ports 44, 46, 48A, 48B, 50, 52, 54, 56A, 56B, 58 of the cartridges 66, 68 (details discussed below). A precise alignment of the opposing ports is not required for the system to actuate under predetermined conditions .

[0055] Circumferential o-ring grooves 74 are disposed along the outer surface 76 of the spool 62. The o-ring grooves 74 are arranged at least on either side of the ports 72 of the fluid transfer channel 70. Once the o-rings 76 are placed in the o-ring grooves 74, a circumferential gap 80 is formed between the o-rings 78, the spool 62, and cartridges 66, 68, and a substantially fluid tight axial seal between the spool 62 and the cartridges 66, 68 is created. During fluid transfer, the fluid is substantially contained within the circumferential gap 80 as fluid is transferred into the spool 62 from one of the ports 72, and out of the spool 62 through the other port 72 and through the cartridges 66, 68 to the pressure sense unit 18. The circumferential gap 80 provides for sufficient volume for fluid flow to allow for the lack of precise alignment of the spool ports 72 with the cartridge ports 44, 46, 48A, 48B, 50, 52, 54, 56A, 56B, 58.

[0056] Biasing device recesses 82 can be bored longitudinally along the center-line of the spool 62 at one or both ends (as shown). The biasing device recesses 82 are sized to receive the biasing device 64 and to provide freedom of motion of the biasing device 64 as the biasing device 64 articulates through the full range of motion of the spool 62. Each spool 62 has a pair of opposing biasing device 64 (one rightward biasing and the other leftward biasing) to center the spool 62 within the cartridges 66, 68 when the system is a rest or when the operating pressures (Pi and P2) are equal.

[0057] The cartridges 66, 68 include a substantially longitudinal bore 84 along the centerline of the cartridges 66, 68. The longitudinal bore 84 has an inner surface 86 slightly greater than the outer surface 76 of the spool 62. Grooves 88 disposed circumferential along the cartridge outer surface 90 assists in the transfer of fluid from the flow sense unit 16 to the pressure sense unit 18 (discussed in detail below) . Within the grooves 88 are the opposing ports 44, 46, 48A, 48B, 50, 52, 54, 56A, 56B, 58 as discussed above. The ports 44, 46, 48A, 48B, 50, 52, 54, 56A, 56B, 58 are holes machined or otherwise drilled through the thickness of the cartridges 66, 68. Circumferential o-ring grooves 92 along the outer surface 90 of the cartridges 66, 68 are ideally disposed between the fluid transfer grooves 88. Once the o- rings 94 are arranged in the o-ring grooves 92 a substantially fluid tight axial seal is formed and fluid is substantially contained within the select fluid transfer groove 88 as fluid is conveyed through the groove 88 to the pipes or tubes 36 (FIGS. 6A, 6B) connected to the pressure sense unit 18.

[0058] The LP and HP cartridges 66, 68 are basically the same except for the longitudinal distances between the center- lines of the entrance and exit ports 44, 46, 48A, 48B, 50, 52, 54, 56A, 56B, 58, illustrated in FIG 8. The longitudinal distances B, C, D, E between the centerlines of the ports 44, 46, 48A, 48B, 50 of the LP cartridge 66 are less than the longitudinal distances B', C, D', E' between the centerlines of the ports 52, 54, 56A, 56B, 58 of HP cartridge 68. Also, the distance A, F from the ends of the LP cartridge 66 to the center-line of outer ports 44, 50 of the LP cartridge 66 are less than the distance A', F' from the ends of HP cartridge 68 to the center-line of outer ports 52, 58 of the of HP cartridge 68. The predetermined differences in the port centerlines results in a time delay in the high pressure fluid being conveyed out of the spool 62 through the exit port and into the HP cartridge 68 compared to the LP cartridge. This creates a predetermined time delay sufficient for the low pressure fluid to communicate with pressure sense unit 18 before the high pressure fluid communicates with the pressure sense unit 18. As will be explained in detail below, the pressure sense unit 18 will activate (piston 100 is longitudinally displaced) when the low pressure fluid exceeds a predetermined pressure value. The activation of the pressure sense unit 18 will switch the pressure sense unit fluid entrance port from the high pressure port 108 (Pi or P2 pressure) to the ambient port 106.

[0059] Now returning to FIGS. 4 and 7, each fluid transfer switch 32, 34 includes stem 60. The function of the stem 60 is to translate or move the spool 62 either to the left or right within the bore 84 of the cartridge 66, 68 depending on the pressure differential encountered by the diaphragm plates 26. The stem 60 is generally a longitudinal member having one end 96A connected to the piston plate 28 and its other end 96B connected to the spool 62. An exemplary connection method is externally threading at least one or both of the ends 96A, 96B of the stem 60. The piston plate 28, for example, can have two internally threaded holes 98 aligned with the centerline of the stems 60. Similarly, the LP and HP spools 62 can include an inner threaded hole 150 at one end to receive and secure the stem 60. Other conventional connecting means, such as press fit, welding, and screws/blots are also acceptable for securing the stem 60 to the piston plate 28 and the spools 62.

[0060] Now turning to FIG. 5, the pressure sense unit 18 includes a piston 100, biasing device 102, and a housing 104. The housing 104 includes an ambient pressure port 106, high pressure inlet port 108, low pressure inlet port 110, pressure sense unit outlet port 112, internal cavity 114, pressure plate 116, and a cartridge 118. One end 119 of the housing 104 includes a recess 120 to seat the biasing device 102. The housing inner surface 122 is slight larger than the outer surface 124 of the piston 100 such that the piston 100 is capable of freely translating within the internal cavity 114. A fluid transfer channel 126 is a circumferentially groove around the piston 100 to provide fluid conveyance between the ambient pressure port 106 and high pressure inlet port 104 to the pressure sense unit outlet port 112. Circumferential o- ring grooves 128 are disposed along the outer surface 124 of the piston 100. The o-ring grooves 128 are arranged at least on either side of the fluid transfer channel 126. Once the o- rings 130 are placed in the o-ring grooves 128, a circumferential gap 132 is formed between the o-rings 130, the piston 100, and the cartridge 118, and a substantially fluid tight axial seal between the piston 100 and the cartridge 118 is created. During fluid transfer, the fluid is substantially contained within the circumferential gap 132 as fluid is transferred into the pressure sense unit 18 from the flow sense unit 16 and out of the pressure sense unit 18 and through the cartridge 118 to either ambient or to the isolation valve 12.

[0061] The pressure plate 116 is connected to the piston 100 and provides a uniform load distribution of low pressure onto the piston 100 for smooth actuation of the piston 100 within the internal cavity 114 without binding or jamming. The pressure plate 116 includes a flange 134, which acts as a stop to contact the edge 136 of the cartridge 118 to assure the piston 100 does not actuate longitudinally beyond a predetermined axial distance.

[0062] The piston 100 may also include a bore 138 having a bottom 140 to seat the biasing device 102. The bottom 140 will provide a reactant force surface to counter the force of the biasing device 102 and to reset the piston 100 into a neutral or initial position. [0063] Fluid transfer channels 146 may be, for example, radial holes machined or drilled through the housing 104 and the cartridge 118. O-ring grooves 144 are preferably machined on either side of the fluid transfer channel 146. The o-rings 142 disposed in the o-ring grooves 144 of the cartridge 118 with create an axial fluid seal between the housing 104 and the cartridge 118.

[0064] The biasing device for the flow sensor unit and the pressure sensor unit have resistant coefficients (for example, K-factors for coil springs) commensurate with the predetermined pressure threshold. The biasing device will yield (for example, compress for coil springs) when the predetermined pressure threshold is exceeded. In the case of the flow sensor unit, the pressure force applied to one of the two biasing device by the diaphragm must be greater than the resistant force of the biasing device for the spool to traverse within the cartridge either towards or away from the diaphragm, thereby switching entrance and exit ports. Similarly, the pressure force applied to the piston of the pressure sense unit 18 must be greater than the resistant force of the biasing device for the piston to traverse within the pressure sense unit 18, thereby switching from high pressure entrance port to the ambient pressure exit port.

[0065] An alternative embodiment of the present invention 10, illustrated in FIG. 9, includes a conventional speed control valve 148 connected to the Pi and P2 input ports of the present invention 10 to induce time delays to convey fluids of pressures PI', P2 ' to the flow sense unit 16 and pressure sense unit 18 (discussed in details below).

[0066] Another alternative embodiment of the present invention 10, illustrated in FIG. 10, may include a pneumatic actuator 152 for implementation with a non-diaphragm isolation valve, such as a butterfly valve or a knife-edge valve [0067] Mode of Operation

[0068] In a typical application, an isolation valve 12 with a valve coefficient (CV) of 100 will generate a differential pressure of about 11 psi when 380 gpm passes through the isolation valve 12. Therefore, the flow sense unit 16 will include a differential and a pair of opposing biasing device that will respond when a differential pressure applied by the diaphragm exceeds 11 psi. The description uses examples of thresholds for flow rate and pressures for illustration purposes only and are not intended to limit the present invention to the thresholds or examples contained herein.

[0069] The present invention 10 can be set for different flow conditions, different flow media, or different isolation valves by selecting different biasing device resistant coefficients (for example spring constants for the coil springs that act on each spool). The following is an example of the key characteristics of the fluid conveying system monitored or sensed by of one embodiment of the present invention 10 for detection of a rupture in the fluid conveying system:

[0070] 1. Predetermined flow rate threshold > 380 gpm

[0071] 2. Predetermined minimum pressure threshold < 40 psi

[0072] There are an infinite number of combinations that are determined based on system specifications .

[0073] When a rupture occurs, the pressure of the system decreases and flow increases near the point of rupture. Based upon these two characteristics, the present invention 10 is activated and the isolation valve 12 is "tripped" or closed when both thresholds below are met:

[0074] 1. Flow exceeds the predetermined flow rate of 380 gpm and

[0075] 2. Pressure is below a predetermined minimum pressure of 40 psi. [0076] As discussed above, the present invention 10 is an apparatus that measures the flow rate and the flow direction via the flow sense valve, and the lowest line pressure at the valve with the pressure sense unit 18. The flow sense unit 16 includes a dual cartridge/spool assembly and a flow sense diaphragm assembly. The pressure sense unit 18 includes a single cartridge/spool and pressure sense diaphragm assembly.

[0077] When both thresholds are met, the highest available line pressure, PI or P2, is directed through both the flow sense unit 16 and pressure sense unit 18 to PV that acts on, and closes the isolation valve 12.

[0078] If either threshold 1 or threshold 2 are not met, then PV is exhausted to atmosphere via the flow sense unit 16 or the pressure sense unit 18, respectively.

[0079] In the case of the pipeline flow passing through the isolation valve 12 (for example, a diaphragm valve) from left to right, the flow generates a pressure drop across the valve such that PI is greater than P2, where PI is the upstream pressure and P2 is the downstream pressure. PI and P2 are presented to the sensing diaphragm of the flow sense valve and to the low and high cartridge/spool assemblies of the flow sense unit 16.

[0080] While the flow is less than the predetermined threshold, the high and low pressure cartridge/spool assemblies switch both HP and LP to atmospheric pressure via port E. If the flow rate should increase beyond the flow threshold the corresponding increased differential pressure P1-P2 acting on the flow sense diaphragm cause the spools to move, switching the LP port of the low pressure cartridge/spool assembly from E (atmospheric pressure) to P2 and the HP port of the high pressure cartage/spool assembly from E to PI.

[0081] PI is then presented to the Pressure Sense Valve via port HP, and P2 is presented to the Pressure Sense Diaphragm via port LP. To satisfy threshold 2, P2 needs to be below the preset threshold, which will switch PV from E (atmospheric) to HP (PI) closing the isolation valve 12.

[0082] Should the flow be in the opposite direction, P2 will be greater than PI. If thresholds 1 and 2 are met, P2 will be switched to PV via HP, and Pi will be switch to LP.

[0083] If threshold 1 or threshold 2 are not met PV will be exhausted to atmosphere via the HP and then the Flow Sense Valve, or, the Pressure Sense valve respectively.

[0084] The following five operating conditions further clarify the operation, detailing external conditions and internal device states. Table 1 (below) is an illustration of five examples of the possible conditions monitored/sensed and acted on by the present invention 10 when the isolation valve is an opened position.

Table 1

[0085] Condition 1 (see FIG. 11A)

[0086] 1) Flow below 380 gpm'*

[0087] 2) Pressure below 40 psi¹

[0088] 3) P1=P2

[0089] *based on specific isolation valve characteristics and fluid conveying system specifications

[0090] Flow Sense Spool: Center

[0091] Pressure Sense Spool: Right [0092] In the flow sense valve, the differential pressure was under 11 psi (flow did not exceed 380 gpm). Both the high pressure and low pressure spools will be balanced in the center position by internal springs. The pressure (LP) and pressure (HP) are vented through the exhaust ports (E) to atmospheric pressure. The flow sense valve ports pressure (LP) to the piston arrangement within the pressure sense valve.

[0093] In this case, pressure LP (E) is not greater than 40 psi, therefore the piston in the pressure sense unit 18 will be forced to the right by an internal spring. When in the right position, the pressure sense valve is porting pressure (HP) to the diaphragm valve in the pipeline (PV). Recall that pressure HP is atmospheric pressure (E).

[0094] Isolation valve 12 is not actuated.

[0095] Condition 2 (FIG. 11B) :

[0096] 1) Flow above 380 gpm

[0097] 2) Pressure above 40 psi

[0098] 3) P1>P2

[0099] Flow Sense Spool: Right

[00100] Pressure Sense Spool: Left

[00101] In the flow sense valve, the differential pressure was over 11 psi (flow exceeded 380 gpm), pressure PI greater than P2. Both the high pressure and low pressure spools are driven to the right position. In this position the low- pressure cartridge is porting pressure P2 to LP and the high- pressure cartridge ports pressure Pi to HP.

[00102] In this case, pressure LP (P2) is greater than 40 psi, and the piston in the pressure sense unit 18 will be forced to the left against a spring. When in the left position, the pressure sense valve is porting atmospheric pressure (E) to the diaphragm valve in the pipeline (PV). [00103] Isolation valve 12 is not actuated.

[00104] Condition 3 (FIG. 11C):

[00105] 1) Flow above 380 gpm

[00106] 2) Pressure below 40 psi

[00107] 3) P1>P2

[00108] Flow Sense Spool: Right

[00109] Pressure Sense Spool: Right

[00110] In the flow sense valve, the differential pressure was over 11 psi (flow exceeded 380 gpm), pressure PI greater than P2. Both the high pressure and low pressure spools are driven to the right position. In this position the low- pressure cartridge is porting pressure P2 to LP and the high- pressure cartridge ports pressure PI to HP.

[00111] In this case, pressure LP (P2) is not greater than 40psi , therefore the piston in the pressure sense unit 18 will be forced to the right by an internal spring. When in the right position, the pressure sense valve is porting pressure (HP) to the diaphragm valve in the pipeline (PV). Recall that pressure HP is equal to pressure PI.

[00112] Isolation valve 12 is actuated.

[00113] Conditions 4 (see FIG. 11D):

[00114] Flow above 380 gpm

[00115] Pressure above 40 psi

[00116] P2>P1

[00117] Flow Sense Spool: Left

[00118] Pressure Sense Spool: Left

[00119] In the flow sense valve, the differential pressure was over 11 psi (flow exceeded 380 gpm), pressure Pi less than P2. Both the high pressure and low pressure spools are driven to the left position. In this position the low-pressure cartridge is porting pressure Pi to LP and the high-pressure cartridge ports pressure P2 to HP.

[00120] In this case, pressure LP (Pi) is greater than 40 psi, and the piston in the pressure sense unit 18 will be forced to the left against a spring. When in the left position, the pressure sense valve is porting atmospheric pressure (E) to the diaphragm valve in the pipeline (PV) .

[00121] Isolation valve 12 is not actuated.

[00122] Conditions 5 (see FIG. HE):

[00123] 1) Flow above 380 gpm

[00124] 2) Pressure below 40 psi

[00125] 3) P2>P1

[00126] Flow Sense Spool: Left

[00127] Pressure Sense Spool: Right

[00128] In the flow sense valve, the differential pressure was over 11 psi (flow exceeded 380 gpm), pressure Pi less than P2. Both the high pressure and low pressure spools are driven to the left position. In this position the low-pressure cartridge is porting pressure PI to LP and the high-pressure cartridge ports pressure P2 to HP.

[00129] In this case, pressure LP (PI) is not greater than 40psi , therefore the piston in the pressure sense unit 18 will be forced to the right by an internal spring . When in the right position, the pressure sense valve is porting pressure (HP) to the diaphragm valve in the pipeline (PV). Recall that pressure HP is equal to pressure P2.

[00130] Isolation valve 12 is actuated.

[00131] Operation Under Dynamic Conditions [00132] In a piping system several dynamic conditions need to catered for,

[00133] 1. Startup or priming transient

[00134] 2. Multiple valve interaction

[00135] Start up and Transient Operation.

[00136] Under startup conditions, high flow transients may occur, while the line pressures are below the minimum pressure. When the pressure is above 40 psi during such a transient, the internal delays inside the unit may still result in a false trigger. The types of isolation valves used can further compound the problem of dealing with transients.

[00137] Consider the case of a typical diaphragm operated valve, with the present invention 10 resting in Condition 1 above. In this condition the valve is not actuated (i.e. the actuating diaphragm sees atmospheric pressure), but in a diaphragm valve the diaphragm rests in the closed position and is opened by the line pressure.

[00138] The rising pressure inside the pipeline first encounters the closed diaphragm causing a pressure spike to occur while the diaphragm is being opened. As the diaphragm valve opens with the line pressure the air behind the diaphragm must be exhausted to atmosphere. Meanwhile the initial pressure spike has moved the flow sense spool preventing the air to escape and possibly directing the upstream pressure into the diaphragm chamber. If the diaphragm chamber was filled with water, instead of air the conflict caused by the pressure transient is further exacerbated. Slowing down the speed of response of the flow sense valve will permit the line pressure to open the diaphragm valve before the exhaust path is shut off. Once the diaphragm is open, if the downstream pressure is above the trip point, the valve will remain un-actuated for the remainder of the high flow transient. It also follows that the flow sense valve response is should also slow enough to allow the line pressure to build above the pressure trip point.

[00139] Since the flow sense valve not only detects the flow rate but also directs the high and low pressure to the appropriate HP and LP ports, the pressure sense valve will not see the downstream pressure until the flow reaches a significant value above normal. The result could be that the isolation valve will see the actuation pressure even though the downstream pressure is above the trip threshold. To reduce this effect, the LP port is switched at a lower flow rate than the HP port. For example, in the case of the conditions described above, the HP port is switched at 380 gpm but the LP port is switched at 280 gpm allowing the pressure sense valve to operate on the correct downstream pressure.

[00140] Multiple Valve Interaction

[00141] The present invention 10 is designed to operate in multi-valve multi path systems, and therefore need to interact with other similar valves in the system, which may manipulate the operating conditions that the valve sees. Consider the valve network section in FIG 12A that represents a typical application.

[00142] The valves are positioned to segment a header supplying sprinkler branch lines, represented by the loads. In any one system there may be many such headers . The loads may or may not be applied and are independent of each other, i.e. load 1 may be on but not load 2. The supply may also be from either direction, or both dependent how the system is configured.

[00143] Condition: Rupture between Valve 1 and Valve 2 (See FIG. 12B)

[00144] Description:

[00145] Valves 1 and 2 are required to close to maintain the integrity of the system. Initially, valve 3 will begin to close with valve 2. Only if load 3 flow is zero, Valve 3 will react to the back pressure generated by valve 2 closing, self correct and reopen (Condition 4). If however flow is being supplied to load 3, the flow will prevent sufficient backpressure to be generated by valve 2. Valve 3 will continue to close (Condition 5), producing a sub optimal isolation.

[00146] Now consider the same rupture scenario, with delays applied as per FIG. 12C.

[00147] The delays are applied such that the valves furthest from the pump, relative to the direction of flow, react to a rupture first. In the above example if flow is flowing from left to right, valve 3 is set to close first, e.g. at 5 seconds, where as valve 1 is set for 15 seconds. Similarly if flow is from right to left valve 3 is set for 15 seconds and valve 1 is set for 5 seconds. When the rupture occurs, valve 1 and valve 2 will respond to the rupture and close, valve 2 will close in 10 seconds and valve 1 in 15 seconds. Valve 3 will be subjected to similar conditions as valve 2, but the delay will prevent closure unless the conditions persist for 15 seconds. In the above scenario valve 2 will have closed after 10 seconds, valve three will then only be subject to the normal flow an pressure conditions generated by load 3. Delays are generated by independently restricting the flow into the present invention 10 from each pressure port by fixed orifices, needle valves or other similar adjustable restrictors.

[00148] Reset

[00149] A closed isolation valve will reopen when PI & P2 equalized, or if the downstream system pressure falls rises above the pressure level required to hold the isolation valve shut and the flow decreases below the threshold. If during a closing actions the flow drops below the flow threshold, or the pressure rises above the pressure threshold the present invention 10 will re—open the isolation valve. [00150] Figures 13A-13H are pictorial views of an alternative embodiment of the flow sense unit for the present invention of Figure 1. The alternative embodiment of the flow senor unit functions similar to ones discussed above. A diaphragm (not shown) will move based on differential pressure measured by the flow sense unit and in this case a rack and gear train will convert the linear motion of the piston (not shown) to rotary motion. The two rotary valves are positioned to channel the pressure to the appropriate ports as discussed above. The rotary valves could be spherical shape as shown or a straight or tapered plug type.

[00151] Although the invention has been described with respect to various embodiments, it should be realized that this invention is also capable of a wide variety of further and other embodiments all within the spirit and scope of the appended claims.

Claims

What is claimed is:

1. A method for detecting and isolating a rupture in a fluid conveying system, said method comprising the steps:

A. mechanically sensing pressure upstream (PI) and downstream (P2) at or near the isolation valve;

B. mechanically determining whether the fluid conveying system flow is greater than a predetermined flow;

C. mechanically determining whether the downstream pressure (P2) is below a predetermined pressure; and

D. mechanically closing the isolation valve in response to conditions set forth in Steps B and C being satisfied.

2. The method according to claim 1 further comprising the steps :

E. mechanically determining whether PI equals P2; and

F. mechanically opening the isolation valve in response to conditions set forth in Step F being satisfied.

3. The method according to claim 1 further comprising the steps:

G. mechanically determining whether downstream pressure (P2) is greater than the required pressure to hold the isolation valve closed; and

H. mechanically opening the isolation valve in response to conditions set forth in Step G being satisfied.

4. The method according to claim 1 further comprising the steps :

I. mechanically determining whether the fluid conveying system flow is lower than a predetermined flow; and

J. mechanically opening the isolation valve in response to conditions set forth in Step I being satisfied.

5. An apparatus for detecting a supply line rupture and for closing an isolation valve upon detection of the rupture, said apparatus comprising:

a fluid flow sense unit being capable of producing a pressure differential based on fluid flow characteristics in the supply line upstream and downstream at or near the isolation valve; and

a pressure sense unit in fluid communication with said fluid flow sense unit and with the isolation valve, said pressure sense unit being capable of mechanically actuating the isolation valve to either an open or closed position in response to said pressure differential satisfying predetermined pressure differential conditions.

6. An apparatus according to claim 5 wherein said fluid flow sense unit comprises:

a diaphragm assembly capable of sensing said pressure differential in the fluid conveying system as the fluid passes through in the isolation valve; and

a fluid transfer switch operably connected to said diaphragm assembly and being capable of actuation in response to said pressure differential satisfying said predetermined pressure differential conditions.

7. The apparatus according to claim 6 wherein:

said diaphragm assembly includes, a Pi chamber, a P2 chamber, at least one diaphragm plate disposed between said PI chamber and said P2 chamber, a housing to enclose said PI chamber, said P2 chamber, and said least one diaphragm plate, and a piston bracket operably connected to said at least one diaphragm plate for the activation of said fluid transfer switch; and

said fluid transfer switch includes, a housing having a plurality of entrance and exit ports, said exit ports in fluid communication with said pressure sense unit; a low pressure fluid transfer switch being disposed within said housing; and a high pressure fluid transfer switch being disposed within said housing; wherein each of said switches includes, a substantially cylindrical spool having two ends, a fluid transfer channel, and a plurality of fluid transfer channel exit ports; a stem having a first end and a second end, said stem being operably connected to said piston bracket at a first end and operably connected to said spool at a second end, opposing biasing devices disposed at both ends of said two ends of said spool; and a substantially cylindrical cartridge having a plurality of fluid transfer ports, two ends, and a bore sized to receive said spool, said stem, and said opposing biasing devices,

whereby said entrance and said exit ports of said housing switch therebetween when said stem translates said spools either to left or right position within said bore depending on said pressure differential sensed by said at least one diaphragm plate and depending on whether the pressure force applied to said one biasing device by said at least one diaphragm plate is greater than a resistant force of said one biasing device.

8. The apparatus according to claim 7 wherein said opposing biasing devices have resistant coefficients commensurate with said predetermined pressure differential conditions.

9. The apparatus according to claim 7 wherein said fluid transfer channel is substantially "U" shaped.

10. The apparatus according to claim 7 wherein said spool fluid transfer channel exit ports are substantially aligned with said cartridge fluid transfer ports.

11. The apparatus according to claim 7 wherein:

said plurality of fluid transfer channel exit ports of said low pressure cartridge have longitudinal distances between centerlines of said plurality of fluid transfer channel exit ports less than longitudinal distances between centerlines of said plurality of fluid transfer channel exit ports of said high pressure cartridge; and

said ends of said low pressure cartridge have longitudinal distances to center-lines of outer ports of said plurality of fluid transfer ports of said low pressure cartridge less than a distance from said ends of said high pressure cartridge to center-lines of outer ports of said plurality of fluid transfer channel exit ports of said high pressure cartridge,

whereby a predetermined time delay is created such that low pressure fluid communicates with said pressure sense unit before high pressure fluid communicates with said pressure sense unit.

12. The apparatus according to claim 5 wherein said pressure sense unit comprises:

a housing having a plurality of fluid transfer channels, an ambient pressure port, a high pressure inlet port, a low pressure inlet port, a pressure sense unit outlet port in fluid communication with the isolation valve, and an internal cavity,

a pressure plate juxtaposition to said low pressure inlet port and being responsive to pressure forces applied by low pressure fluid conveyed through said low pressure inlet port;

a piston disposed within said internal cavity and operably connected to said pressure plate, said piston having a first end and a second end, said piston capable of freely translating within said internal cavity; and

a biasing device disposed within internal cavity juxtaposition to said second end of said piston, said biasing device capable of resetting said piston into a neutral or initial position by applying an opposing force in response to the applied force of said pressure plate acting on said piston,

whereby said pressure sense unit fluid entrance port switches from the high pressure port (PI or P2 pressure) to the ambient port when said piston actuates longitudinally in response to low pressure fluid satisfying said predetermined pressure differential conditions.

13. The apparatus according to claim 12 wherein said piston comprises a circumferential fluid transfer channel to provide fluid conveyance between said ambient pressure port and said high pressure inlet port to said pressure sense unit outlet port.

14. The apparatus according to claim.12 wherein:

said biasing device has resistant coefficients commensurate with said predetermined pressure differential condition,

whereby said pressure sense unit switches from said high pressure entrance port to said ambient pressure exit port when pressure force applied to said piston of the pressure sense unit is greater than said opposing force of said biasing device causing said piston to traverse within said pressure sense unit.

15. The apparatus according to claim 5 wherein the isolation valve is a diaphragm valve.

16. The apparatus according to claim 5 wherein the isolation valve is a non-diaphragm valve and said apparatus further comprises a pneumatic actuator operably connected to said non- diaphragm isolation valve to actuate said non-diaphragm valve to either an open or closed position.

17. The apparatus according to claim 5 further comprising a speed control valve operably connected to Pi and P2 input ports to induce time delays to convey fluids of pressures Pi ' , P2 ' to said flow sense unit and said pressure sense unit.

18. The apparatus according to claim 5 further comprising a time delay mechanism operably connected to said pressure sense unit to vary the time to close the isolation valve.

19. The apparatus according to claim 18 wherein said time delay mechanism is a flow restrictor.

20. A method of detecting and isolating ruptures within a multi- path fluid conveying system having a plurality of isolation valves, said method comprising:

(a) independently sensing pressure upstream (PI) and downstream (P2) at or near each isolation valve;

(b) independently determining at each isolation valve whether a rupture has occurred in its fluid conveying path based on Step (a) pressure measurements;

(c) initiating a time delayed closing of each isolation valve that detects a rupture in its fluid conveying path, wherein time delays vary for each isolation valve; and

(d) reopening each isolation valve when conditions indicate that the rupture condition has passed.