GB2158616A

GB2158616A - Hydraulic operated pressure reducing valve

Info

Publication number: GB2158616A
Application number: GB08411991A
Authority: GB
Inventors: Anthony Charles Robert Johnson
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-05-10
Filing date: 1984-05-10
Publication date: 1985-11-13
Also published as: GB8411991D0

Abstract

A pressure reducing valve for use in a water distribution main 4 consists of a butterfly 2 or similar type of valve, having a rotating element 15 requiring actuator 12 to control it. The actuator is driven by means of the fluid pressure in the main 4 acting on pistons 12 or a moving vane, acting through a linkage or a rack and pinnion, to rotate the valve element. The actuator is controlled by means of a pilot regulator 10, which senses the pressure in the water main and applies fluid pressure to the actuator so that, in combination with the valve, it maintains the pressure in the main at a pre-determined valve. <IMAGE>

Description

SPECIFICATION Hydraulic operated pressure reducing valve This specification describes a valve for the control of pressure in water distribution mains. Such valves are generally manufactured to designs specifically for this purpose. The specification describes the adaption of a more generally available type of valve to perform the same task.

The particular type of valve described is of the form of a butterfly valve, plug valve or ball valve, in which the moving element is mounted on a spindle so that rotation of the spindle by a quarter turn moves the valve from open to closed or from closed to open. Such valves when installed in pipes may be used to regulate flow in the pipes by adjustment of the angular position of the spindle which rotates the moving element. The rotation of the valve spindle is generally achieved by means of a quarter turn electric or pneumatic actuator. For the purpose of this specification a water driven actuator is described and it is controlled by a pilot regulator so that the action of the valve, the actuator and the regulator is such that the assembly of these items in the manner described comprises a mechanism for the control of pressure in a water pipe.

The pressure control valve is described by reference to the drawing (Fig. 1) provided herewith, in which the water supply pipe (1) is fitted with a butterfly valve (2) or other suitable valve, in such a manner that under particular conditions of flow, the pressure of the water in the low pressure side (3), which is downstream of the valve, is regulated by the action of the valve such that it may be held at a desired value which is less than the pressure upstream of the valve referred to as the high pressure side (4).

The pressure in the low pressure side is applied by means of a capilliary tube or small bore pipe known as the signal line (5) to the pilot diaphragm (6) of the pilot regulator unit (7). This pressure is balanced by the action of the spring (8) which is adjusted by pilot adjusting spring (9) so that the pilot regulator piston (10) controls the action of the control ports in response to the difference between the force applied to the pilot shaft (11) due to the pilot spring and the force due to the pressure applied through the signal line to the pilot diaphragm.

The pilot regulator unit is arranged to provide motive water to operate the valve (2) by means of a piston (12) in a cylinder (13) driving the valve spindle (14) through a rack and pinnion mechanism (15). The piston is fitted with a return spring (16) so that it will travel towards the cylinder head (17) when the fluid between the piston and the cylinder head is free to escape and in so doing the valve (2) will open. When water pressure is applied through the control line (18), which is a small bore pipe connected to the regulator unit (7) at one end and the cylinder (13) at the other, the force on the piston is arranged to be such that the pressure exerted by the return spring is overcome and the piston travels away from the cylinder head so that the valve closes.

The pilot regulator unit (7) is connected at its supply port (19) through the supply line (20) to the high pressure side of the water supply pipe to provide motive water for driving the piston under the control of the action of the ports in the pilot regulator. When the pressure in the low pressure side of the water supply pipe is less than that which is determined by the pressure of the spring (8) on the diaphragm (6), the pilot regulator piston (10) causes the control port (21) to open into the vent port (22) so that fluid is expelled from the cylinder (13) under the action of the return spring and the piston travels so as to cause the valve (2) to open.

When the pressure in the low pressure side of the water supply pipe is greater than that determined by the action of the spring (8) on the diaphragm (6), the pilot regulator piston causes the control port (21) to open into the supply port (19) so that motive water flows into the cylinder so that the piston moves away from the cylinder head and causes the valve (2) to close.

The action of opening and closing the valve (2) by means of the piston and cylinder connected to the valve spindle under the control of the pilot regulator unit (7) is such that the pressure in the low pressure side (3) of the water supply pipe (1) is controlled to a value which is determined by the adjustment of the pilot regulator unit (7).

Figure 1 shows the necessary elements in the design so that the principle of operation can be described. Additional features are now described which improve the design.

A single cylinder is shown driving the valve spindle by means of a rack and pinnion mechanism. A design, incorporating two pistons, one situated to each side of the valve spindle, and arranged to work in opposite directions, provides more operating force and more accurate control.

Complete shut-off of the valve (2) is not desirable in some applications and the design would then incorporate means to prevent the valve from closing onto a seat. In such an arrangement, the butterfly element would be undersized in relation to the pipe diameter or would be perforated with one or more holes so that the changes of pressure resulting from small movements of the valve close to its closed position are not too great and so that the pressure surges which might otherwise be caused, are avoided.

The valve is shown driven by means of a rack and pinnion mechanism, for the purposes of clearly demonstrating the principle of operation.

Alternative designs may be constructed, having the same effect. Such designs include those employing linkages and levers used in conjunction with cylinders and those employing a moving vane or diaphragm otherwise arranged to impart rotary motion to the valve spindle.

1. A pressure reducing valve comprising a valve mounted in the pipe in which pressure is to

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Hydraulic operated pressure reducing valve This specification describes a valve for the control of pressure in water distribution mains. Such valves are generally manufactured to designs specifically for this purpose. The specification describes the adaption of a more generally available type of valve to perform the same task. The particular type of valve described is of the form of a butterfly valve, plug valve or ball valve, in which the moving element is mounted on a spindle so that rotation of the spindle by a quarter turn moves the valve from open to closed or from closed to open. Such valves when installed in pipes may be used to regulate flow in the pipes by adjustment of the angular position of the spindle which rotates the moving element. The rotation of the valve spindle is generally achieved by means of a quarter turn electric or pneumatic actuator. For the purpose of this specification a water driven actuator is described and it is controlled by a pilot regulator so that the action of the valve, the actuator and the regulator is such that the assembly of these items in the manner described comprises a mechanism for the control of pressure in a water pipe. The pressure control valve is described by reference to the drawing (Fig. 1) provided herewith, in which the water supply pipe (1) is fitted with a butterfly valve (2) or other suitable valve, in such a manner that under particular conditions of flow, the pressure of the water in the low pressure side (3), which is downstream of the valve, is regulated by the action of the valve such that it may be held at a desired value which is less than the pressure upstream of the valve referred to as the high pressure side (4). The pressure in the low pressure side is applied by means of a capilliary tube or small bore pipe known as the signal line (5) to the pilot diaphragm (6) of the pilot regulator unit (7). This pressure is balanced by the action of the spring (8) which is adjusted by pilot adjusting spring (9) so that the pilot regulator piston (10) controls the action of the control ports in response to the difference between the force applied to the pilot shaft (11) due to the pilot spring and the force due to the pressure applied through the signal line to the pilot diaphragm. The pilot regulator unit is arranged to provide motive water to operate the valve (2) by means of a piston (12) in a cylinder (13) driving the valve spindle (14) through a rack and pinnion mechanism (15). The piston is fitted with a return spring (16) so that it will travel towards the cylinder head (17) when the fluid between the piston and the cylinder head is free to escape and in so doing the valve (2) will open. When water pressure is applied through the control line (18), which is a small bore pipe connected to the regulator unit (7) at one end and the cylinder (13) at the other, the force on the piston is arranged to be such that the pressure exerted by the return spring is overcome and the piston travels away from the cylinder head so that the valve closes. The pilot regulator unit (7) is connected at its supply port (19) through the supply line (20) to the high pressure side of the water supply pipe to provide motive water for driving the piston under the control of the action of the ports in the pilot regulator. When the pressure in the low pressure side of the water supply pipe is less than that which is determined by the pressure of the spring (8) on the diaphragm (6), the pilot regulator piston (10) causes the control port (21) to open into the vent port (22) so that fluid is expelled from the cylinder (13) under the action of the return spring and the piston travels so as to cause the valve (2) to open. When the pressure in the low pressure side of the water supply pipe is greater than that determined by the action of the spring (8) on the diaphragm (6), the pilot regulator piston causes the control port (21) to open into the supply port (19) so that motive water flows into the cylinder so that the piston moves away from the cylinder head and causes the valve (2) to close. The action of opening and closing the valve (2) by means of the piston and cylinder connected to the valve spindle under the control of the pilot regulator unit (7) is such that the pressure in the low pressure side (3) of the water supply pipe (1) is controlled to a value which is determined by the adjustment of the pilot regulator unit (7). Figure 1 shows the necessary elements in the design so that the principle of operation can be described. Additional features are now described which improve the design. A single cylinder is shown driving the valve spindle by means of a rack and pinnion mechanism. A design, incorporating two pistons, one situated to each side of the valve spindle, and arranged to work in opposite directions, provides more operating force and more accurate control. Complete shut-off of the valve (2) is not desirable in some applications and the design would then incorporate means to prevent the valve from closing onto a seat. In such an arrangement, the butterfly element would be undersized in relation to the pipe diameter or would be perforated with one or more holes so that the changes of pressure resulting from small movements of the valve close to its closed position are not too great and so that the pressure surges which might otherwise be caused, are avoided. The valve is shown driven by means of a rack and pinnion mechanism, for the purposes of clearly demonstrating the principle of operation. Alternative designs may be constructed, having the same effect. Such designs include those employing linkages and levers used in conjunction with cylinders and those employing a moving vane or diaphragm otherwise arranged to impart rotary motion to the valve spindle. CLAIMS

1. A pressure reducing valve comprising a valve mounted in the pipe in which pressure is to be controlled, an actuator to operate the valve and a pilot regulator to control the actuator.

2. A pressure reducing valve as claimed in claim 1 wherein the valve employs a butterfly disk a ball or a plug attached to a spindle for the control of the flow of a fluid.

3. A pressure reducing valve as claimed in claim 1 where the valve is controlled by a quarter turn actuator, which rotates the spindle claimed in claim 2.

4. A pressure reducing valve as claimed in claim 1 where the actuator comprises one or more pistons mounted in cylinders and a mechanism to translate the movement of the pistons into rotation of the valve spindle as claimed in claim 2.

5. A pressure reducing valve as claimed in claim 1 in which water taken from the pipe in which pressure is controlled is passed through a pilot regulator to the actuator as claimed in claim 3 and employed as motive water for moving the pistons.

6. A pressure reducing valve as claimed in claim 1 wherein the pilot regulator senses the pressure which is being controlled and regulates the supply of motive water to the pistons as claimed in claim 4 to effect motion of the valve spindle as claimed in claim 2 in such a way as to maintain the desired pressure.

7. A pressure reducing valve substantially described herein with reference to the accompanying drawing.