GB2427015A

GB2427015A - Ball valve

Info

Publication number: GB2427015A
Application number: GB0511918A
Authority: GB
Inventors: Christopher J Parsloe
Original assignee: PARSLOE CONSULTING Ltd
Current assignee: PARSLOE CONSULTING Ltd
Priority date: 2005-06-11
Filing date: 2005-06-11
Publication date: 2006-12-13
Also published as: GB0511918D0

Abstract

A valve comprises a valve body 10 having a valve chamber, inlet 11 and outlet 12 ports communicating with the valve chamber, a rotatable valve element 18 located within the valve chamber and movable between a valve open position and a valve closed position. The valve element 18 has a passage 19 therethrough defining an inlet 20 and outlet 21 in the valve element that are in alignment with the inlet and outlet ports when the valve is in the open position. An inspection port 13 communicates with the valve chamber and has an opening that is in alignment with the passage 19 through the valve element when the valve is in the closed position. The passage 19 through the valve element is provided with a removable flow restrictor 22.

Description

I

Valves

Field of the Invention

The invention relates to valves, more particularly to ball valves for the regulation of fluid flow.

Background of the Invention

A variety of valve designs have been used for regulating the flow of fluids through pipelines. Such valves are employed, for example, in heating, ventilating and air conditioning systems to isolate and to balance the rate of flow of water between circuits. Some valves permit the measurement of available circuit differential pressure when the valve is in the closed position. In a valve with a fixed memory, the valve's resistance when regulated is constant and remains unchanged when the valve is closed and then re-opened.

An example of a commercially available valve providing these functions is a variable orifice double regulating valve in which an oblique pattern globe valve has a pressure tapping on each side of the valve orifice.

The size of the orifice is controlled by advancing or retracting an elliptical plug into or out of a tapered valve seat designed to accommodate the plug and allow the passage of liquid through an annular orifice in the seat around the plug. For a given degree of opening, the pressure drop across the valve can be measured and equated to flow rate. A locking mechanism is built into the valve handle so that once the flow has been regulated, the valve can be locked, then closed and re-opened to its regulated position.

Alternatively, ball valves are known in which liquid flow through a passage in the ball element is regulated by passing the liquid through an orifice at the inlet to the passage. The size of the orifice can be varied by rotation of the ball. More particularly, on rotation of the ball the area of the orifice through which liquid passes is reduced as the opening provided by the orifice becomes concealed by the ball housing.

Another type of ball valve is known for isolating but not regulating liquid flow in which a removable basket strainer is held in the passage through the ball element. The basket strainer acts as a coarse filter that removes particulates from the liquid. When the valve is in the closed position, an inspection port situated between the inlet and outlet ports of the valve allows access to the basket strainer thereby permitting its removal and replacement. The strainer is designed not to restrict the flow of liquid through the valve.

As flow regulating valves are required for devices that are increasingly sensitive to flow such as fan coil units and chilled beams, improvements over the known types of fluid flow regulating valves are required. In particular, there is a need for retaining high accuracy flow measurement. In this regard, the flow measurement accuracy of a variable orifice valve decreases significantly as the valve is closed and the opening becomes smaller. There is also a need for a valve which is less prone to blockage due to the nature of the orifice opening. For example, in the variable orifice double regulating valve described above, the variable orifice valve opening is in the form of an annulus which is more prone to blockage than a simple circular orifice. Further, it is desirable to reduce the pressure loss that occurs with existing valves in order to achieve less energy consumption. Additionally, in view of the complexity of the known valves, a simpler and therefore less expensive valve to produce is required.

The present invention aims to overcome one or more of these deficiencies.

Brief summary of the Invention

The invention provides a valve comprising a valve body having a valve chamber, inlet and outlet ports communicating with the valve chamber, a rotatable valve element located within the valve chamber and movable between a valve open position and a valve closed position, the valve element having a passage therethrough defining an inlet and outlet in the valve element that are in alignment with the inlet and outlet ports when the valve is in the open position, an inspection port communicating with the valve chamber having an opening that is in alignment with the passage through the valve element when the valve is in the closed position characterised in that the passage through the valve element is provided with a removable flow restrictor.

The flow restrictor should, preferably, be capable of consistently and repeatedly generating sufficient pressure drop to enable the volumetric flow rate of fluid through the flow restrictor to be calculated from measurements of the pressure drop.

Desirably, the flow restrictor has been calibrated before use, and may be marked with its resistance value. The conventional resistance value, k, for a given fluid, may be measured in a test rig under controlled conditions, and after measurement may be marked on to the flow restrictor itself, by stamping, engraving, printing or the like. The conventional resistance value k is that flow rate, expressed in cubic meters per second, through a flow restrictor, which generates a pressure drop across the restrictor of one bar. It is specific for every fluid.

Brief Description of the Drawings

A schematic representation of a ball valve in accordance with the invention is shown in the accompanying drawings wherein: Figure 1 is a plan view of the valve.

Figure 2 is a section view of the valve shown in Figure 1 in a plane containing the axes of the three ports, showing the valve in the open position.

Figure 3 is a section view according to Figure 2 showing the valve in the closed position.

Detailed Description of the Invention

The valve is of the type having a rotatable valve element such as a ball valve element or valve element that is cylindrical, a ball valve element being preferred.

A removable flow restrictor is positioned in the passage through the valve element in order to regulate the flow of fluid when the valve is in the open position. Unlike known valves used for flow regulation in which the orifice size and configuration of the valve is variable, the size and configuration of the orifice in the valve of the invention is not variable.

Using known valves, the valve orifice requires adjustment to meet the flow regulation requirement of the specific task for which it is being employed.

The valve orifice then needs to be maintained at the correct adjustment.

Disadvantages associated with the use of known valves are referred to above.

In contrast, using a valve of the present invention, accurate flow regulation is achieved by inserting a dedicated flow restrictor in the valve.

With knowledge of the required flow for a given application and by measuring the available fluid pressure, it is possible to determine the size of the flow restrictor required.

While the flow restrictor may be located at any position from the inlet to the outlet of the passage through the valve element, it is most conveniently positioned at the mouth of the passage that is adjacent the opening of the inspection port when the valve is in the closed position.

In a preferred embodiment of the invention the passage through the valve element has a circular cross section.

The flow restrictor may be a plate having an orifice communicating with the passage through the valve element. Preferably, the plate is circular and has a circular orifice concentric with the passage through the valve element.

Fluid flow is regulated by the configuration of the orifice and the passage through the flow restrictor. For example, the flow through a circular orifice in a thin plate will be largely determined by the diameter of the orifice. Alternatively, a flow restrictor having a longer tubular passage therethrough may be employed in which the length of the passage will also influence the flow rate. In this respect, a flow restrictor having a streamlined passage of the venturi type may be employed.

The flow restrictor is removably connected to the valve element. The flow restrictor may be releasably mounted in a recess in the valve element surrounding the mouth of the passage through the valve element. For example, the rim of a circular plate flow restrictor may be seated in an annular recess formed around the mouth of the passage through the valve element. A suitable retainer clip ring may also be releasably mounted in a groove in the recess in order to retain the flow restrictor in its operative position in the valve element. Alternative ways of connecting the flow restrictor to the valve element include providing the flow restrictor and the mouth of the passage through the valve element with threaded portions such that the flow restrictor can be screwed into the valve element.

In a preferred embodiment the valve is provided with a pressure measurement port having access to the fluid flow space on the upstream side of the flow restrictor and a pressure measurement port having access to the fluid space on the downstream side of the flow restrictor. The location of the pressure measurement ports may vary. For example, the ports may be either side of the valve element. Alternatively, when the flow restrictor is positioned at the mouth of the passage through the valve element, one of the pressure measurement ports may be provided by a hole through the valve body such that, when the valve is in the open position, the hole is in alignment with a hole through the valve element communicating with the passage through the valve element.

Preferably, each pressure measurement port comprises a seal for preventing the escape of fluid through the port. As a practical matter, the particular design adopted for the pressure measurement ports will be one that is adapted to receive a proprietary pressure measurement tapping.

Any suitable pressure measuring system may be employed including a commercially available needle probe e.g. a Binder probe or a manometer.

The end of the inspection port of the valve remote from the valve chamber is preferably provided with a removable closure. For example, the end may be a threaded male end or a threaded female end to which a screw cap may be attached.

The ends of the inlet and outlet ports of the valve used to connect the valve to the pipework may take any desired form. For example, the ends may be threaded male ends or threaded female ends, union ends or ends to serve joints to copper or plastic pipes.

The valve may be manufactured using conventional materials.

Metals and metal alloys are preferred including steel, brass or other copper zinc alloys.

The valve may be supplied with a number of different calibrated flow restrictors so that the appropriate flow restrictor can be selected on site for any given application. As mentioned above, it is possible to calculate the size of the flow restrictor required, and more specifically the resistance value k, from a knowledge of the flow needed for a given application and by measuring the available fluid pressure. With the inlet and outlet ports of the valve connected to the pipework and with the valve in the closed position, it is possible to measure the available circuit differential pressure through the pressure measurement ports. Having calculated the size or resistance value of the flow restrictor required it may be inserted and attached through the inspection port when the valve is in the closed position. By opening the valve with the flow restrictor in place it is possible to measure the pressure differential across the valve to confirm that the desired flow rate has been achieved. If necessary, the flow rate can be adjusted by replacing the flow restrictor with one that is more appropriate.

An example of a valve in accordance with the invention is illustrated in the accompanying drawings.

Figure 1 shows the exterior of the ball valve in plan view. The valve has a valve body 10 enclosing a valve chamber and is provided with an inlet port 11 in alignment with an outlet port 12. An inspection port 13 has an axis perpendicular to and in the same plane as the axis of the inlet and outlet ports. The inspection port is provided with a removable cap 14.

Pressure measurement ports 15 and 16 are shown protruding from the valve body on either side of the valve chamber. The stem of a handle 17 is connected to the valve element inside the valve chamber. The valve can be opened and closed by rotation of the handle and consequently the valve element through a quarter turn.

Figure 2 shows the valve in cross section in the plane containing the axis of the inlet port 11 and the outlet port 12, and the axis of the inspection port 13. The valve is shown in the open position. The valve chamber enclosed by valve body 10 contains a ball valve element 18. The ball valve element 18 is in sealed contact with the valve chamber by a conventional rubber or plastics seal 32 between element 18 and body 10. The ball valve element 18 has a passage 19 therethrough having an inlet 20 and an outlet 21. In the valve open position shown, the inlet 20 and outlet 21 are in alignment with the inlet port 11 and outlet port 12 of the valve body.

A removable calibrated flow restrictor 22 in the form of a circular plate having a central circular orifice 23 is positioned at the inlet 20 of the passage 19 through the ball valve element 18. The flow restrictor is positioned in an annular recess 24 in the valve element 18 at the inlet 20. It is held in place by means of a circlip 25 inserted into a retaining groove in the recess 24.

When in use, fluid flows through the inlet port 11 and the flow restrictor 22 before leaving the valve through exit port 12. The size of the orifice in the flow restrictor accurately regulates the flow of fluid through the valve. The ball valve element 18 seals the opening to the inspection port 13 when the valve is in the open position. An 0-ring seal 34 between the cap 14 and the mouth of inspection port 13 prevents fluid leakage from the inspection port even when the valve is in the closed position (Fig. 3) .

The pressure measurement ports 15 and 16 are shown in greater detail in Figure 2. Each port comprises an internally threaded tubular aperture 26, 27 having an axis perpendicular to the surface of the valve body in which a means for sealing the aperture may be held. The means for sealing may be a blanking plug, or a self-sealing proprietary pressure tapping of a kind well known in the art. In either case, conventional jointing material may be used to seal the threaded joints thus formed in the apertures 26, 27.

In one suitable commercially available design, a port seal permits the insertion of a pressure measuring needle probe through the seal into the fluid space. Such a seal may take the form of one or more resilient 0rings or grommets under compression so that the apertures therein are closed.

Insertion of the probe forces open the apertures in the resilient material which then forms a seal around the probe.

Each aperture communicates with the valve chamber by means of a bore 28, 29. A needle probe for measuring pressure may be inserted through a pressure tapping retained in the sealed aperture 26 and bore 28 in order to measure the pressure upstream of the flow restrictor 22.

Similarly, a needle probe for measuring pressure may be inserted through a pressure tapping retained in the sealed aperture 27 and bore 29 in order to measure the pressure downstream of the flow restrictor 22 when the valve is in use.

Figure 3 shows the valve in the closed position when the ball valve element 18 has been rotated a quarter turn. Fluid flow from the inlet port 11 to the outlet port 12 is blocked by the ball valve element 18. The passage 19 through the ball valve element 18 is now in alignment with the passage in the inspection port 13. The flow restrictor 22 is adjacent the opening of the inspection port 13 into the valve chamber and is easily accessible through the exterior opening of the inspection port when the inspection port cap 14 is unscrewed and removed.

Just as a flow restrictor can be initially inserted through the inspection port 13, positioned and secured in position by the circlip 25, the flow restrictor can be removed by reversing the steps taken for its placement and replaced with a different flow restrictor if required.

In the embodiment shown, the inlet, outlet and inspection ports of the valve are of conventional design having internal bores that are substantially circular in cross section. The bores of the inlet and outlet ports 30,31 are threaded to receive externally threaded pipes, not shown.

Claims

1. A valve comprising a valve body having a valve chamber, inlet and outlet ports communicating with the valve chamber, a rotatable valve element located within the valve chamber and movable between a valve open position and a valve closed position, the valve element having a passage therethrough defining an inlet and outlet in the valve element that are in alignment with the inlet and outlet ports when the valve is in the open position, an inspection port communicating with the valve chamber having an opening that is in alignment with the passage through the valve element when the valve is in the closed position characterised in that the passage through the valve element is provided with a removable flow restrictor.

2. A valve according to claim I wherein the rotatable valve element is a ball valve element.

3. A valve according to claim 1 or claim 2 wherein the flow restrictor is positioned at the mouth of the passage through the valve element that is adjacent the opening of the inspection port when the valve is in the closed position.

4. A valve according to any one of the preceding claims wherein the flow restrictor is a plate having an orifice communicating with the passage through the valve element.

5. A valve according to claim 4 wherein the plate is circular and has a circular orifice concentric with the passage through the valve element.

6. A valve according to any one of the preceding claims comprising a pressure measurement port having access to the fluid flow space on the upstream side of the flow restrictor and a pressure measurement port having access to the fluid space on the downstream side of the flow restrictor.

7. A valve according to claim 6 wherein each pressure measurement port comprises a seal for preventing escape of fluid through the port.

8. A valve according to claim 6 wherein each seal permits the insertion of a pressure measuring needle probe.

9. A valve substantially as hereinbefore described with reference to and as illustrated in the accompanying Figures.