Patent Application
20100071787
The present invention generally relates to automatic valves, such as those employed on municipal water utility systems. More particularly, the present invention relates to a system for hydraulically adjusting and managing pressure between set points so as to control pressure downstream of a main valve in such a fluid distribution system.
There is a general understanding throughout the worldwide water supply industry that instances of water loss are common in many water distribution networks and in many instances the level of water loss can be relatively high. The amount of water loss in the system is due to a variety of leak sources, such as improperly tightened pipe flange connections, leaking flange gaskets, leaking valve seals, failed seals, old pipes (with pinhole bursts), loose fittings, leaky faucets, etc. The sum of these sources of leakage can add up to a substantial amount of water loss. Maintaining the entry point pressure at all times at the level necessary to provide adequate pressure at the distant points for periods of high demand can result, during periods of low demand, in excessive pressure at the consumer's premises, and thus increased waste of water by unnecessary consumption and leakage. The volume of water lost through leakage is directly related to pressure in the system.
Automatic pressure reducing valves are used in water distribution systems to reduce pressure to a pre-determined value or sub-point that is adequate, but does not expose normal components, such as household hot water tanks, to overpressure. The sub-point is typically determined to provide minimum pressure that meets criteria of the water utility, particularly under maximum or “peak” demand conditions which can occur when a fire is being fought. The pressure required for peak demand is usually significantly higher than that required for “off-peak”, such as typical nighttime conditions. Under low demand conditions, not only does leakage form a higher proportion of the total demand, but investigation has implied that some leak orifices can actually increase in area with pressure, aggravating the problem if excessive pressures are maintained at all times.
Various attempts have been previously made to reduce such losses by introducing a degree of control over the supply pressure in response to demand. One known system uses electrical circuit means with pressure and flow-rate sensors from monitoring pressure and flow-rate and then processing the information obtained and using it in turn to control suitable electrically operated valve means. Such systems are, however, relatively complex and expensive and require a continuous external power supply giving rise to additional capital and running costs and reliability problems.
There also exist flow-driven valves which use fluid pressures to control actuation of the main valve, and thus are independent of external power sources and can be used in essentially any location. One such flow-driven valve system is disclosed in U.S. Pat. No. 5,967,176 to Blann, et al. The system controls high and low pressures by utilizing the pressure drop across an orifice plate that is installed in the main line, usually attached directly to the inlet or outlet flange of the main valve. The pressure control is independent of the main valve position, and is a direct function of system flow. The pressure control device monitors the pressure drop or flow across the orifice plate. Control pressure is varied based upon the movement of a pilot valve member with respect to a fixed pilot valve member, which in turn controls the main control valve.
However, this system has many shortcomings. The diameter of the orifice plate may need to be customized for different high/low flow applications. For example, a smaller orifice diameter may be required if flows are not sufficient to develop the required pressure drop across the system orifice. Likewise, the system orifice may need to be increased if pressure drops are too large because a smaller orifice can limit the flow capacity of the system. The orifice plate also decreases the capacity of the main valve. This is particularly a concern when high flow is necessary, such as a high flow of water to fight a fire or the like. The added orifice plate limits the capacity of the main valve for fire flow situations. Moreover, it is difficult to retrofit existing valves with this system as the flange spacing must be modified to accommodate the orifice plate, typically requiring removal of the main valve from the line.
Accordingly, there is a continuing need for an improved flow-driven valve system for automatically controlling downstream pressure between selected set points. The present invention fulfills these needs and provides other related advantages.
The present invention resides in a system and method for hydraulically managing fluid pressure downstream of a main valve. As will be more fully described herein, the system is flow-driven and responds to changing flow demand downstream from a main valve, so as to manage and control the fluid pressure downstream from the main valve between predetermined set points. The system is designed to hydraulically open the main valve assembly during high demand conditions, and close the main valve during low demand conditions, resulting in a reduction of the amount of water loss in a waterworks system downstream of the main valve assembly.
The system embodying the present invention for hydraulically managing fluid pressure in a fluid distribution system between pressure set points generally comprises a main valve having a main valve body defining a fluid inlet and a fluid outlet. A main valve seat is disposed between the fluid inlet and the fluid outlet. A main valve member is movable between an open position away from the main valve seat and a closed position towards the main valve seat. A main valve diaphragm is coupled to the main valve member, the main valve diaphragm and the main valve body, or a cover thereof, defining a pressure control chamber. The main valve is configured to open to increase fluid flow therethrough, and to close to reduce fluid flow therethrough.
A variable orifice assembly is coupled to the main valve. The variable orifice assembly comprises a housing attachable to the main valve and defining an inner chamber. A plurality of fluid apertures, typically at least three apertures, are formed through the housing for coupling the inner chamber to a source of fluid. A valve stem is disposed within the inner chamber of the housing and movable generally along a length of the inner chamber in response to the main valve opening and closing. The valve stem has a non-uniform outer configuration, creating a fluid pathway thereover. In a particularly preferred embodiment, the valve stem outer configuration forms multiple variable area fluid flow passageways or slots. Fluid flow between the fluid apertures is dependent, in part, on the position of the valve stem within the inner chamber.
The variable orifice assembly also includes a sleeve which is disposed between the valve stem and an inner wall of the housing defining the inner chamber. The sleeve is selectively movable along a length of the inner chamber to vary the fluid flow between the fluid apertures of the housing. An actuator, such as a manually rotatable nut, is coupled to the housing and the sleeve for selectively moving the sleeve.
A stop plate is also disposed within the housing, between an end of the valve stem and the main valve for limiting travel of the valve stem within the housing. A second actuator, such as a second manually rotatable nut, is coupled to the housing and the stop plate for selectively moving the stop plate.
A rod is extendable through an aperture of the stop plate so as to engage the valve stem at one end thereof, and is engageable or coupled to a valve member of the main valve at a generally opposite end thereof. The valve stem is biased towards the stop plate, and moved away from the stop plate by the rod. The valve stem is variably positioned within the housing to alter the fluid flow between the fluid apertures. The valve position and the fluid flow are variable as the main valve opens and closes.
A first control pilot device is in fluid communication with the main valve and a first fluid aperture of the variable orifice assembly. A second control pilot is in fluid communication with the main valve and a second fluid aperture of the variable orifice assembly. The first control pilot device is used to set the upper pressure set point of the system, while the second control pilot device is used to set the lower pressure set point of the system. The first and second control pilot devices each include a diaphragm disposed between fluid chambers thereof. The position of the diaphragm is variable depending on the pressure differential between the chambers and a bias applied to the diaphragm. The position of the diaphragm varies the fluid flow between an inlet and outlet thereof.
The first control pilot device is fluidly coupled to the main valve pressure control chamber and directs fluid into the pressure control chamber of the main valve to close the main valve as fluid flow between fluid apertures of the variable orifice assembly coupled to the first and second control pilot devices is restricted. Fluid is allowed to flow out of the pressure control chamber of the main valve and open the main valve as fluid flow between the fluid apertures of the variable orifice assembly is less restricted. The position of the stop plate and sleeve of the variable orifice assembly, and the degree of bias of the valve stem of the variable orifice assembly can all be altered to adjust pressure gradients for the system.
Other features and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.
The accompanying drawings illustrate the invention. In such drawings:
As shown in the accompanying drawings, for purposes of illustration, the present invention is directed to adjustable hydraulically operated pressure management control valve systems. As will be more fully described herein, the present invention is directed to a system for hydraulically managing fluid pressure in a fluid distribution system between pressure set points so as to manage fluid pressure downstream of a main valve of the fluid distribution system. The systems of the present invention are particularly adapted for use in the waterworks industry where there is a desire to reduce the amount of water loss in the system due to leaks. The invention can reduce the amount of water loss in a system by reducing the system pressure as the flow or system demand decreases. A common example would be a residential water system where water demand is high during the day and low at night. If the pressure is lower during low usage, then a lower pressure will result in lower water losses throughout the system.
With reference now to
With reference now to
As illustrated in
With continuing reference to
As can be seen in
The valve stem 212 of the variable orifice assembly 200 is biased downwardly and towards a stop plate 220 by means of a spring 218. The stop plate 220 has an aperture 222 formed therein which is typically of a smaller diameter than the diameter of the valve stem 212. One or more other apertures 224 are also formed therein so as to provide a fluid flow pathway between fluid apertures 208 and 210. The stop plate 220 can be variably positioned within the housing 202, particularly in the lower chamber area of inner chamber 204 between apertures 208 and 210. Such is done in order to limit the travel of valve stem 212. The stop plate 220 can be selectively moved by means of an actuator, typically in the form of a manually rotatable nut 226, which is rotatably coupled to the housing 202 and the stop plate 220 for selectively moving the stop plate 220 upwards or downwards depending upon the direction of rotation of the nut 226.
The variable orifice assembly 200 is typically connected to the main valve 100, by means of a threaded connection 228 to the cover 118 of the main valve 100, such that a rod 230 of the variable orifice assembly 200 is coupled to the main valve stem 112, so as to be moved as the main valve 100 is opened and closed. The aperture 222 of the stop plate 220 is of a sufficient diameter to permit the rod 230 to extend therethrough and engage the variable orifice valve stem 212 and move it upwardly or away from the stop plate 220. Although the housing 202 of the variable orifice assembly 200 is coupled to the main valve member 100, and the rod 230 allowed to move into the main valve 100 and extend into the inner chamber 204 of the variable orifice assembly 200, the fluid pressures within the inner chamber 204 of the variable orifice assembly 200 and the main valve 100 are isolated from one another. This is done, for example, by means of an O-ring 232 through which the rod 230 extends.
With continuing reference to
With continuing reference to
With reference again to
A diaphragm 312 is attached to the stem 310 and forms a variable control pressure chamber 314. This pressure chamber 314 is fluidly connected to the intermediate or second fluid aperture 208 of the variable orifice assembly, such as by means of conduit 28. A spring 316 applies a bias to the diaphragm 312 and stem 310. The amount of bias can be controlled by means of turning screw 318 so as to compress or decompress spring 316.
It will be readily understood that when pressurized fluid is directed into the pressure chamber 314, the diaphragm 312, and thus the stem 310 will move upwardly, causing poppet 308 to move into a closed or restricted position, thus closing off the pathway between the inlet 304 and the outlet 306 of the control pilot device 300. However, when the fluid pressure in pressure chamber 314 is lowered, the bias of spring 316 causes the diaphragm 312 to move downwardly, and thus poppet 308 to move downwardly, and out of engagement with seat 320 and open the fluid passageway between the inlet 304 and the outlet 306. Adjustment of spring 316, by means of screw or actuator 318 directly impacts the upper pressure set point, or high flow set point of the system 10.
With continuing reference to
Once again, a spring 420 is used to bias the position of the diaphragm 412, which can be adjustably controlled by means of a set screw 422. The set screw 422 can be turned to compress or decompress spring 420, which will impact the bias of diaphragm 412. Turning the set screw 422 adjusts the low pressure set point.
Thus, control pilot device 300 adjusts the maximum high pressure during high flow conditions, such as illustrated in
With reference now to
When pressure at P1 and P2 are substantially equal, pressure reducing control pilot device 300 is regulating downstream pressure P3 at the low pressure set point. During this condition, the main valve 100 is operating at or near the closed position, as illustrated in
During main valve 100 normal to high flow situations, as illustrated in
As the pressure downstream of main valve 100 decreases, the pressure in chamber 416 decreases, and diaphragm 412 is moved upwardly by spring 420. This closes the passageway between the inlet 404 and outlet 406 of the control pilot device 400, and the fluid pressure through conduit 30 is reduced. As the main valve 100 starts to open, the flow area through the variable area passageways or slots 214 and 216 changes. The relative change in slot flow area is such that flow area through the upper slot 216 gradually decreases while flow area through the lower slot gradually increases, as illustrated in
As pressure P1 becomes greater than P2, pressure reducing control pilot device 300 responds by regulating downstream pressure P3 towards the higher pressure set point, as illustrated in
As the main valve 100 opens, the stem 212 of the variable orifice assembly 200 likewise travels, causing the flow area through the variable area passageways 214 and 216 to change, as described above, as the main valve 100 continues to open.
The shape of each slot, or variable area fluid flow passageways 214 and 216 can be customized to achieve a desired pressure regulation profile between low and high pressure set points. The transition between low and high pressure is a function of the slot 214 and 216 profiles and the adjusted position of the sleeve or stem guide 234 and the stop plate 220.
With reference now to
With reference now to
With reference now to
With reference now to
When installing or before doing any adjustment, the manual nuts 238 and 226 of the variable orifice assembly 200 are turned fully anti-clockwise. The air from the variable orifice assembly 200 is drained, such as using screw 244.
The isolation ball valve 42 is closed, and the outlet high pressure PH is adjusted with pressure reducing control pilot device 300 using adjusting screw 318 until the setting is increased to the desired high pressure set point, as illustrated in
The system flow should be equal to the high flow QH. The isolation valve 42 is reopened. The control pilot device 400 is adjusted using set screw 422 so that pressure gauge P1 is higher than the valve outlet pressure. The upper nut for the sleeve 238 of the variable orifice assembly 200 adjusts the starting position of the high modulation point MH. The upper nut 230 of the variable orifice assembly is turned clockwise until downstream pressure starts to fall, and then back counterclockwise until high pressure PH adjustment is again reached, as illustrated in
System flow should be equal to flow QL. The minimum downstream pressure PL is adjusted using the control pilot device 400. An increase in differential pressure control lowers minimum downstream pressure PL, and in reverse a decrease in differential pressure control pilot device 400 increases minimum downstream pressure PL, as illustrated in
The lower nut actuator 226 for the stop plate 220 adjusts the starting position of the low modulation point MH. The lower nut 236 is turned clockwise until downstream pressure starts to increase, and then turned back counterclockwise until low pressure PL is again reached, as illustrated in
Although several embodiments have been described in detail for purposes of illustration, various modifications may be made without departing from the scope and spirit of the invention. Accordingly, the invention is not to be limited, except as by the appended claims.
| Number | Date | Country | |
|---|---|---|---|
| 61118376 | Nov 2008 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12062946 | Apr 2008 | US |
| Child | 12625011 | US | |
| Parent | 11927474 | Oct 2007 | US |
| Child | 12062946 | US |
