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System and method for hydraulically managing fluid pressure downstream from a main valve

System and method for hydraulically managing fluid pressure downstream from a main valve description/claims

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 hydraulically adjustable pressure management control valve designed to control pressure downstream of a main valve.

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” or 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 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 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 engaging the main valve seat. The main valve is configured to hydraulically open to increase fluid flow therethrough, and hydraulically close to reduce fluid flow therethrough. A main valve diaphragm is coupled to the main valve member. The main valve diaphragm and the main valve body, or a cover thereof, define a control chamber having a control port in fluid communication with a pilot control device.

A variable orifice assembly is coupled to the main valve so as to open a variable orifice thereof as the main valve is opened, and close the variable orifice as the main valve is closed. A fixed orifice is in fluid communication with an outlet of the variable orifice. A control device is operably associated with the main valve, an inlet of the fixed orifice and an outlet of the fixed orifice, and configured to detect pressure differentials between the inlet and the outlet of the fixed orifice and open and close the main valve in response to the detected pressure differentials. The control device is fluidly coupled to the control chamber of the main valve, so as to hydraulically open and close the main valve member.

The variable orifice assembly comprises a housing having a fluid inlet in fluid communication with the main valve inlet. A fluid outlet of the variable orifice assembly is in fluid communication with the fixed orifice and a control device. A stem is slidably disposed within the housing and coupled, or engagable with, the main valve member. The stem and housing cooperatively define the variable orifice between the inlet and outlet of the housing of the variable orifice assembly. A sleeve may be disposed between the stem and the housing, having an aperture therethrough, the sleeve, stem and housing cooperatively forming the variable orifice. The sleeve may be adjustably positioned within the housing to vary the fluid flow from the housing inlet to the housing outlet.

The control device typically comprises a control pilot valve apparatus having a high pressure regulating chamber in fluid communication with the inlet of the main valve as well as the main valve control chamber. The control pilot valve apparatus also has low pressure regulating chambers in fluid communication with the outlet of the variable orifice and the outlet of the fixed orifice. The low pressure regulating chambers are separated by a flexible diaphragm supporting an elongated stem. The high pressure regulating chamber is at least partially defined by a second flexible diaphragm, and includes a fluid flow passageway therethrough. A moveable poppet extends from the second flexible diaphragm and into the fluid flow passageway of the high pressure regulating chamber. The poppet extends into a first end of the atmospheric chamber, and the stem extends into a generally opposite end of the atmospheric chamber.

Depending upon the pressures within the chambers of the control pilot valve apparatus, the stem is moved into engagement with the poppet, or the second flexible diaphragm moves the poppet, to alter the flow through the passageway of the high pressure regulating chamber. This results in an alteration of hydraulic pressure in the control chamber of the main valve so as to open or close the main valve. In a particularly preferred embodiment, an atmospheric chamber is disposed between the high and low pressure regulating chambers.

In a particularly preferred embodiment, the control pilot valve apparatus comprises a housing having a fluid low pressure regulating chamber disposed therein. The fluid low pressure regulating chamber is divided into first and second sub-chambers by a first flexible diaphragm. Each sub-chamber has a fluid inlet. A fluid high pressure regulating chamber is disposed within the housing, and includes a fluid passageway intermediate an inlet and an outlet thereof. The fluid high pressure regulating chamber is at least partially defined by a second flexible diaphragm. An atmospheric chamber is disposed between the fluid low pressure regulating chamber and the fluid high pressure regulating chamber. A poppet is slidably disposed within the atmospheric chamber. A stem extends from the first flexible diaphragm into the atmospheric chamber and is movable into contact with the poppet. Movement of the poppet by either the stem, or the second flexible diaphragm, due to fluid pressure variations in the high fluid pressure regulating chamber or the low pressure regulating chamber varies fluid flow between the inlet and outlet of the fluid high pressure regulating chamber. This alters the fluid pressure in the control chamber of the main valve, so as to hydraulically open or close the main valve member.

The first flexible diaphragm is selectively biased with a first spring. The first spring is selectively adjustable to limit the movement of the stem to a selected range defining a lower pressure set point. Similarly, the second flexible diaphragm is selectively biased with the second spring. The second spring is selectively adjustable to limit the movement of the poppet to a selected range defining an upper pressure set point.

A pressure regulator apparatus may be disposed between the fluid conduit inlet and the fluid inlet of the variable orifice assembly to customize and regulate the pressure entering into the variable orifice assembly. The pressure regulator comprises a housing having a fluid inlet and a fluid outlet. A selectively adjustable fluid passageway is disposed between the fluid inlet and fluid outlet.

In accordance with the present invention, a method for controlling fluid pressure downstream a main valve comprises the steps of providing a main valve having a fluid inlet and a fluid outlet. The main valve is configured to open to increase fluid flow therethrough, and close to reduce fluid flow therethrough. A variable orifice is associated with the main valve such that the variable orifice opens as the main valve is opened and closes as the main valve is closed. A fluid stream, having a pressure substantially matching a fluid inlet pressure of the main valve, is passed to an inlet of the variable orifice. An inlet of a fixed orifice is placed in fluid communication with an outlet of the variable orifice. A pressure differential between the inlet and outlet of the fixed orifice is detected, and the main valve is opened or closed in response to the detected fixed orifice pressure differential.

In a particularly preferred embodiment, the main valve is opened or closed hydraulically. This is done by means of a control pilot valve apparatus in fluid communication with the variable orifice, the fixed orifice, and the main valve. The control pilot valve apparatus detects the pressure differential between the inlet and outlet of the fixed orifice, and hydraulically opens or closes the main valve.

In one embodiment, a first portion of the fluid stream exiting the outlet of the variable orifice is passed to a first chamber of a low pressure control chamber of the pilot valve apparatus. A second portion of the fluid stream exiting from the outlet of the fixed orifice is passed to a second chamber of the low pressure control chamber of the pilot valve apparatus. The first and second chambers have a first flexible diaphragm therebetween.

A second fluid stream is generated which has a pressure substantially equal to the fluid inlet pressure of the main valve. A first portion of the second stream is passed through a first chamber of a high pressure chamber of the control pilot valve apparatus, which is at least partially defined by a second flexible diaphragm. The first portion of the second stream is passed through a variable valve, into a second chamber and subsequently an outlet of the high pressure chamber. A second portion of the second stream is passed through a hydraulic control chamber of the main valve.

The variable valve of the high pressure chamber is opened or closed in response to detected pressures within the high pressure chamber and low pressure chamber. The main valve is hydraulically opened by lessening the second portion of the second stream as the variable valve of the high pressure chamber is opened. The main valve is hydraulically closed by increasing the second portion of the second stream as the variable valve of the high pressure chamber is closed.

• Provisional Patent
• Utility Patent

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