GB2067716A - Throttling in valves - Google Patents

Abstract

A fluid flow control valve in which flow between an inlet port 3 and an outlet port 4 can be throttled by the inclusion of one of a series of interchangeable members 10 having an orifice whose size varies from member to member, the selection of a member of desired size thereby controlling the flow of fluid. <IMAGE>

Description

SPECIFICATION Valves This invention relates to valves and more particularly to fluid flow control valves for use in heating systems, chilled water systems and the like.

In general the system associated with heating and chilled water circuits employs two valves, one of which is on the inlet side of the circuit and the other is on the outlet side. Whereas the valve on the inlet side generally has an orifice of a fixed size for a given circuit, the valve on the outlet side can be adjusted to increase or decrease the fluid pressure drop across the valve and thereby increase or decrease the mass flow through the circuit. In the case of both valves it is essential that the fluid flow can be throttled if it is desired to isolate the circuit.

Although fixed for a given circuit, the inlet valve orifice size will differ from circuit to circuit and will be dependent on the pressure drop required across the valve. The present invention provides a valve in which the desired orifice size may be readiiy selected without recourse to an expensive mechanism or time-consuming adjustment.

In accordance with the invention, there is provided a fluid flow control valve in which means for throttling flow is provided between the inlet port and an outlet port, characterised in that at least one of the ports is provided with means for receiving and retaining interchangeable members having an orifice of desired size to control the flow of fluid through the valve.

The valves of the invention may be based on any conventional design, particularly ball valves and wedge valves.

The interchangeable members are preferably a series of plates providing a range of orifice sizes.

The valves must be adapted to receive one such plate and means must be provided to hold it firmly in a port so that its orifice is presented to the fluid flowing through the valve.

The plate is preferably forced against an abutment or abutments in the vale port and is advantageously held in that position by means of a hollow retaining nut screwed into the port. In such a preferred embodiment therefore at least a portion of the port receiving the disc carries female threads whereas the retaining nut carries corresponding male threads.

Alternatively and equally preferably, the plate may be formed integrally with the hollow retaining nut and simply screwing the nut into the port sufficiently far to force it against an abutment in the port allows a desired size orifice to be positioned in the port.

Provision of a number of plates having different orifice sizes allows the flow of fluid through the standard valve to be controlled as desired by selection of a plate having a correct sized orifice for a given use. Clearly the orifices for the different plates need not be of the same shape. Depending on the flow pattern required through the valve, the orifice may be, for example, rectangular, round, square or triangular. Generally it is preferred for the orifice plate to be inserted in the inlet port of the valve. In addition it is common for the orifice plate to be in the form of a disc.

It is convenient for pressure tappings to be provided in the valve at both sides of the orifice plate so that the pressure drop across the valve can be ascertained.

The valves of the invention will now be further described, by way of example only, by reference to the accompanying drawings in which: Figure 1 is a sectional view of a conventional "wedge gate" valve having an orifice disc contained in an inlet port thereof.

Figure 2 is a sectional view of a parallel facedsingle "wedge gate" valve having an orifice disc contained in an outlet port thereof.

With regard to Figure 1 the valve shown therein comprises a main body portion 1 to which is fixed by means of engaging screw threads an upper body portion 2. Laterally extending cylindricalshaped portions 3 and 4 of the main body portion 1 define an inlet port and an outlet port respectively.

A wedge-shaped gate 5 has female threads at 8 which engage with a non-rising spindle 6. The spindle is surmounted by a hand wheel 7 and is contained within the main body portion 1 and upper body portion 2. Rotation of the hand wheel 7 causes the gate 5 to be raised or lowered by means of the interaction between the threads at 8.

Figure 1 shows the valve in a closed position with the gate 5 engaging a recess 9 of the main body portion and thereby fully closing the passageway between the inlet port at 3 and the outlet port at 4. Rotation of the hand wheel causes the gate 5 to be gradually withdrawn from the passageway into the chamber defined between the main body portion and the upper body portion and thereby opens the valve.

An orifice disc 10 having an orifice of desired size and shape is positioned against an abutment 11 of the main body portion and is held rigidly in that position by means of a hollow retaining nut 12 having male threads which engage with female threads on the laterally extending portion 3.

In operation of the valve, therefore, the orifice of the disc 10 determines the mass flow of fluid through the valve when it is in the open position.

Different size orifices can be employed in a given valve therefore simply by interchanging the disc 10 with another disc. The pressure difference across the valve can be ascertained by means of pressure tappings at 13 and 14.

In certain cases, a more critical control of the mass flow of fluid through the valve gate can be achieved by use of an orifice disc in conjunction with means for limiting the degree to which the valve can be opened, for example by selecting a disc having an orifice of desired shape and size and additionally providing means whereby a valve gate 5 can be moved from the closed position by only a predetermined maximum amount.

Preferably, the orifice disc is positioned immediately adjacent the valve throttling means.

Thus, Figure 2 shows a somewhat similar valve to that of Figure 1 with the chief exceptions firstly that the orifice disc 1 is held by retaining nut 2 against an abutment in the outlet port rather than in the inlet port, secondly that the wedge gate 3 has one wedge shaped face 4 and one face 5 parallel to, and adjacent to, the face of the orifice disc 1, and thirdly that a valve positioning locknut arrangement is provided on the spindle 6 so that movement of the gate 3 from the closed position can be limited. If such movement is limited so that the orifice is never fully opened, this can in certain cases allow for more control of the fluid flow to be exercised.

Claims (9)

1. A fluid flow control valve in which means for throttling flow is provided between an inlet port and an outlet port, characterised in that at least one of the ports is provided with means for receiving and retaining interchangeable members having an orifice of desired size to control the flow of fluid through the valve.

2. A valve according to Claim 1 in which the interchangeable members are a series of plates.

3. A valve according to Claim 2 in which the plate having the orifice of desired size is forced against an abutment in the valve port.

4. A valve according to Claim 3 in which the plate is held against the abutment by means of a hollow retaining nut screwed into the port.

5. A valve according to Claim 4 in which the plate is formed integrally with the hollow retaining nut.

6. A valve according to any preceding Claim in which the orifice is rectangular, round, square or triangular.

7. A valve according to any preceding Claim in which the plate is in the form of a disc.

8. A valve according to any preceding Claim in which pressure tappings are provided at both sides of the plate.

9. A valve substantially as described herein with reference either to Figure 1 or Figure 2.