GB2041165A

GB2041165A - Liquid flow control devices

Info

Publication number: GB2041165A
Application number: GB7903582A
Authority: GB
Original assignee: GARDOM AND LOCK Ltd
Current assignee: GARDOM AND LOCK Ltd
Priority date: 1979-02-01
Filing date: 1979-02-01
Publication date: 1980-09-03

Abstract

A liquid flow control device comprises a passage 12 connecting an inlet 11 and outlet 13, and, in said passage, a throttle 21 and a variable restrictor 24. The throttle comprises a fixed port 23 surrounded by a rigid abutment face 22 which confronts the variable restrictor 24. The variable restrictor 24 comprises a flexible resilient member having an aperture 25 therein, which aperture is aligned with the fixed port and interrupts a concave or recessed face 26 which confronts the abutment face 22 and in use, the pressure differential across the variable restrictor caused by a flow of liquid tends to distort the flexible resilient member towards the abutment 22 so that the effective size of the aperture is decreased. <IMAGE>

Description

SPECIFICATION Liquid flow control devices There are known a large variety of devices for controlling the flow of a liquid whereby to reduce the effects on the flow of variations in the pressure of the supply of the liquid, and such devices are generaliy complex, employ valves actuated by springs or diaphragms, and need to be adjusted or preset to give a selected or predetermined control effect.

An object of the present invention is to provide a flow control device which is relatively simple and therefore less expensive than the known devices.

According to the present invention there is provided a liquid flow control device compris ing an inlet, an outlet, a passage connecting the inlet and outlet, and, in said passage, a throttle and a variable restrictor; wherein said throttle comprises a fixed port surrounded by a rigid abutment face which confronts the variable restrictor; wherein said variable restrictor comprises a flexible resilient member having an aperture therein, which aperture is aligned with the fixed port and interrupts a concave or recessed face which confronts the abutment face; and wherein the resilient member is disposed between the throttle and the inlet.

In use, the pressure differential across the variable restrictor caused by a flow of liquid tends to distort the flexible resilient member so that the concave or recessed face is urged towards the abutment face, and, due to the concavity or recessing of the concave or recessed face, the resilient member tends to distort so as to decrease the effective size of the aperture therein, The shape of and material or materials used in the resilient member can be selected by experiments to give a required progressive decrease of the aperture size in response to a predetermined progressive increase in the pressure differential between predetermined limits, and tests have shown that limits covering a reasonably large range of pressure differentials whilst given a substantially constant or slightly increasing or decreasing flow can be achieved.

The invention further provides a water flow control assembly comprising said liquid flow control device and a manually operable tap disposed to interrupt the passage between the inlet and the variable restrictor.

The invention also provides water heating apparatus, e.g. for a shower, comprising the liquid flow control device or the control assembly and a water heater; wherein the outlet is connected to the water heater; and wherein the resistance to flow of water through the water heater is less than the resistance to flow of water through the liquid flow control device.

The aperture and port are preferably circu lar, and the diameter of the port is preferably slightly (i.e. up to 25%) larger than the nor mal diameter of the aperture.

The invention will be described further, by way of example, with reference to the accom panying drawings, wherein: Figures 1 and 2 show, respectively, vertical and horizontal cross sections of a body of a water flow control assembly incorporating a liquid flow control device according to the invention; and Figure 3 is a graph showing the relative performances of water heating apparatus with and without the liquid flow control device.

Referring to Figs. 1 and 2, the body of the water control assembly is a metal casting 10 which is provided with a water supply inlet 11, a heater supply passage 1 2 which extends from the inlet 11 to a heater supply outlet 1 3 via a heater supply tap 14, a heater return passage 1 5 which extends from a heater return inlet (not shown) to a shower supply outlet 1 6 via a chamber 1 7 of a cooling water tap 18, and a cooling water passage 1 9 which extends to the outlet 1 6 via said tap 18.

The heater supply outlet 1 3 is defined by a metal fitting 20 which incorporates a throttle 21 of the liquid flow control device. The throttle 21 has a planar abutment face 22, provided by an end of the fitting, which face surrounds a fixed circular port 23 which extends through the end of the fitting to the supply outlet 1 3. The liquid flow control device includes a variable restrictor member 24 which has recessed face 26 surrounding a circular aperture 25 which extends through the restrictor and is in axial alignment with the port 23. The peripheral portion of the face 26 is perpendicular to the axis of the aperture 25 and surrounds a part conical inner portion which is inclined to the axis so that the thickness of the restrictor member 24 adjacent the aperture is only about half of its peripheral thickness of about 4mm.The variable restrictor member 24 is moulded from a resilient flexible polymeric material which is resistant to the chemicals found in mains water supplies and is stable in cold and warm water.

In use, the inlet 11 is connected to a mains water supply, the outlet 1 3 is connected to the inlet of an instantaneous water heater, such as an "Alflow" 7000 water heater ("A Iflow" is a Registered Trade Mark of the Applicants), and the heater outlet is connected to the passage 1 5 by the return inlet. When the tap 1 4 is turned on water flows from the mains to the outlet 1 6 via the liquid flow control device and the heater, and cold water can be mixed with the flow from the heater by turning on the tape 18.

In this embodiment, the nominal normal diameter of the aperture 25 is about 3mm and the diameter of the port 23 is about 4mm, whereby to give a resistance to the flow of water which is slightly greater than the resistance to flow presented by the heater at the minimum rate of flow necessary for operation of the heater.

The liquid flow control device functions to keep the flow of water substantially constant irrespective of mains supply pressure variations within a range of about 20 pounds per square inch up to at least 80 p.s.i., the member 24 deforming progressively with increase in the pressure differential applied thereto so as to reduce the effective diameter of the aperture up to the limit wherein the inner portion of the face 26 abuts the abutment face 22.

The effectiveness of the liquid flow control device is illustrated in Fig. 2, which is a graph of water temperature at the outlet 1 6 against time and mains supply pressure. Line 30 shows the performance of the embodiment described, and line 31 shows the performance of the apparatus with the member 24 removed, under otherwise identical conditions.

From line 30 it can be seen that the temperature is substantially constant, and more specifically decreases slightly as the mains pressure is reduced in the increments at the intervals shown from 80 p.s.i. to 20 p.s.i., whereas line 31 shows that the temperature increases sharply to the point 32 at which the heater safety cut out operates, and if the controls are reset at point 33 to re-establish the original temperature at point 34, the temperature again increases with each pressure reduction.

Some of the advantages of the embodiment described are readily recognisable, for example: (1) In domestic dwellings the mains pressure to the shower can fall suddenly by 30 or 40 p.s.i., e.g. if a further demand is made upon the supply, and in the absence of the member 24 the temperature would rise to painful levels.

(2) The member 24 can be mass produced at very low costs, and can be incorporated into a tap, heater or shower apparatus without significantly affecting the total cost of the apparatus.

(3) Where flow rates, and installation flow resistances are known for existing apparatus, a simple union or like fitting, incorporating the throttle and variable restrictor, can usually be fitted into the installation at minimum cost due to the fact that the fitting can be extremely small in comparison with the aforementioned known devices.

The invention is not confined to the precise details of the foregoing example and many variations are possible within the scope of the invention. For example, the abutment face need not be planar, and may be slightly conical, convex, concave, or recessed. The face 26 may be wholly or partially recessed, or may be concavely shaped. The face of the member 24 remote from the face 26 need not be planar as shown and may be convex, concave or recessed, or have shaped portions such as radial or annular ribs to give particular characteristics to the member.

The member may be located in a peripheral seating provided by an extension of the throttle, so as together to serve as an insert for fixing in a passage, and said insert may be externally threaded.

Claims

1. A liquid flow control device comprising an inlet, an outlet, a passage connected the inlet and outlet, and, in said passage, a throttle and a variable restrictor; wherein said throttle comprieses a fixed port surrounded by a rigid abutment face which confronts the variable restrictor; wherein said variable restrictor comprises a flexible resilient member having an aperture therein, which aperture is aligned with the fixed port and interrupts a concave or recessed face which confronts the abutment face; and wherein the resilient member is disposed between the throttle and the inlet.

2. A device as claimed in claim 1, wherein the port is larger than the aperture.

3. A device as claimed in claim 2, wherein the port and aperture are circular.

4. A device as claimed in claim 3, wherein the diameter of the port is up to 25% larger than the diameter of the aperture.

5. A liquid flow control device substantially as hereinbefore described with reference to Fig. 1 of the accompanying drawings.

6. A water flow control assembly comprising a device as claimed in any preceding claim and a manually operable tap disposed to interrupt the passage between the inlet and the variable restrictor.

7. A water flow control assembly substantially as hereinbefore described with reference to Figs. 1 and 2 of the accompanying drawings.

8. Water heating apparatus comprising a water heater in combination with the liquid flow control device as claimed in any one of claims 1 to 5, or in combination with the water flow control assembly as claimed in claim 6 or 7, wherein the outlet is connected to the water heater; and wherein the resistance to flow of water through the water heater is less than the resistance to flow of water through the liquid flow control device.

9. Water heating apparatus substantially as hereinbefore described with reference to the accompanying drawings.