GB2204669A

GB2204669A - Water connection device

Info

Publication number: GB2204669A
Application number: GB8709901A
Authority: GB
Inventors: Lawrence Travers Hiscox
Original assignee: MYCO ENGINEERING Ltd
Current assignee: MYCO ENGINEERING Ltd
Priority date: 1987-04-27
Filing date: 1987-04-27
Publication date: 1988-11-16
Also published as: GB8709901D0

Abstract

A fluid source e.g. mains water supply is connected to a fluid user system e.g. a combination boiler by means including a non-return valve unit 1, a flow regulator 22 and pipework 21 for connecting the valve unit and flow regulator. The valve unit allows fluid flow to the fluid user system but prevents reverse fluid flow from the user system to the fluid source. The check valve unit 1 may have an outlet portion 3 permanently connected to the boiler and a conical inlet passage (16, Fig 2, not shown) in which a flexible pipe 21 may be held manually during top-up of the boiler. The unit 1 may include two identical valve stems 4, 5, 11. <IMAGE>

Description

CONNECTION DEVICE Some closed fluid systems, such as certain domestic heating systems having so-called combination boilers, are operated with the fluid under pressure. The seals between the various components of the system are not perfect, and from time to time the pressure falls below a value required for correct operation. Re-pressurising the system is then necessary. This may be done by connecting the system temporarily to the mains water supply, but care must be taken to ensure that no water flows back into the mains since this could cause pollution of the mains supply, due to the growth of micro-organisms in the warm water of the system, for example.

Thus when, for instance, a domestic heating system having a combination boiler is re-pressurised directly from the mains and the pressure in the mains falls below that in the heating system, the water from the heating system must be prevented from flowing into the mains and possibly polluting the mains water.

There is therefore the need for a reliable and safe method of pressurising a combination boiler in a domestic heating system.

According to one aspect of the present invention a fluid source is connected to a fluid user system by means including a non-return valve unit, a flow regulator and pipework for connecting the valve unit and flow regulator, the valve unit allowing fluid flow to the fluid user system but preventing reverse fluid flow from the user system to the fluid source.

The fluid source is preferably a mains water supply, and the fluid user system is preferably a closed water system, particularly a heating system.

The pipework preferably comprises tubing, particularly flexible tubing which is also resilient and preferably translucent or transparent.

The pipework is preferably attached to the non-return valve unit with a non-permanent push fit connection. If necessary the pipework is then manually retained in its attached position when fluid at the pressure of the fluid source is flowing into the unit.

According to another aspect of the present invention there is provided a non-return valve unit for use when pressurising or re-pressurising a closed fluid system from a pressurised fluid source, the unit comprising an inlet section adapted for connection to a filling pipe, an outlet section adapted for connection to the fluid user system, a central section having a through bore communicating with corresponding bores in the inlet and outlet sections to provide a common fluid passageway, and at least one non-return valve disposed along the common passageway, the valve or valves permitting flow from the inlet to the outlet but preventing flow in the reverse direction.

The inlet section preferably comprises a housing having a through bore with a tapered first section providing a push fit for the filling pipe, the first section opening into a second section of uniform cross-section communicating with the through bore in the central section of the unit. The filling pipe is preferably a flexible tube which, if necessary, is manually retained in the first tapered section of the inlet bore when fluid at the pressure of the fluid source is flowing through the unit.

In a preferred system having two non-return valves disposed in series with one another along the common passageway, each non-return valve preferably comprises a valve stem extending axially along the passageway with a flared head cooperating with a respective valve seat such that the passageway is blocked when at least one of the valves is seated.

Each valve stem is preferably fitted with a sealing member at the valve head. The sealing member is then resiliently urged against the valve seat to close the valve and seal the passageway. The sealing member preferably comprises an O-ring fitted in a recessed portion of the valve stem.

Each valve stem is preferably oriented with its flared head downstream relative to the direction of flow from the inlet to the outlet. The upstream end of the valve stem is then enlarged to present substantial resistance to the flow of fluid along the passageway such that the stem is axially displaced against a resilient bias to open the valve when fluid at the pressure of the fluid source is introduced through the inlet.

Access to the passageway between the two valves is preferably provided through a removable plug to permit inspection and/or drain-off of fluid.

One example of the invention will now be described with reference to the accompanying drawings in which: Fig. 1 is a perspective sketch of a connecting device for connecting a mains water supply to a combination boiler in a domestic heating system.

Fig. 2 is a cross-sectional view through the check valve unit in the device of Fig. 1.

Referring to these drawings, the check valve unit 20 comprises an inlet nozzle 2 and an outlet connector 3 in threaded engagement with opposite ends of a central section 1. The nozzle 2, central section 1 and outlet connector 3 each have a through bore, the respective bores being aligned with one another to form a common passageway.

The assembly consists of two identical check valves in series with one another along the passageway. Each check valve includes a valve stem 4 having an outwardly flared head 11. At the base of the head 11 the stem 4 is recessed and fitted with an O-ring 8. The O-ring 8 of the left hand valve (as viewed in Fig. 2) is resiliently urged against a flared valve seat 12 by a spring 10 acting between a constricted portion 13 of the central section bore 14 and a nut 5 in threaded engagement with the end of the valve stem 4.

The right hand valve is identical to the left hand valve except that a constriction 18 is formed in the bore 17 of the outlet connector 3 instead of in the bore 14 of the central section 1.

A drain screw 6 with a fibre washer 7 provides access to the bore 14 of the central section between the two valves.

Copper washers 9 are located between the inlet nozzle 2 and the central section 1, and also between the central section 1 and the outlet connector 3. The outlet connector 3 has an external thread 15 for screwing the assembly into a supply pipe of a combination boiler for a domestic heating system.

In use, a flexible nylon filling tube 21 has one end connected to the mains supply through a conventional tap 22 and a T-junction (not shown) in the mains pipe. Its other end is inserted in the tapered bore 16 of the inlet nozzle 2 whenever it is desired to fill or replenish a combination boiler to which the outlet connector 3 is connected via a T-junction in the boiler supply pipe.

The angle of the taper and the length of the bore 16 are designed to provide a satisfactory connection between the filling tube 21 and the nozzle 2 when the tube is pushed into the bore. Even so, the filling tube 21 is only retained by frictional contact with the walls of the bore 16. Accordingly in some cases it may be necessary to manually retain the tube in the bore against the pressure of water in the valve. Although it is intended that the tube 21 should be removed from the valve assembly after the boiler has been filled or replenished, should the tube be left mistakenly in the bore 16, this nonpermanent push fit connection assists in preventing any possibility of water flow, in either direction, at times other than when it is required.

For a standard 8mm filling tube, it has been determined that the angle of the taper in the tapered section of bore 16 preferably lies between 30 and 50 relative to the longitudinal axis of the bore, the diameter of the bore progressively narrowing from an initial value of about 8 mm. The length of the tapered section is preferably in the range of 1.8 to 2.0 cm.

If the pressure in the mains is greater than the pressure in the boiler, the resulting pressure difference acting on the end face of nut 5 of each valve will urge the respective valve stems to positions in which the O-rings 8 are lifted away from the valve seats 12. The resulting flow of water from the inlet to the outlet maintains each valve in an open position by acting on the respective valve heads 11 against the bias of the springs 10. As soon as the pressure in the boiler reaches mains pressure, the O-rings 8 are urged back against the valve seats 12 and form a seal preventing flow of water in the reverse direction. In this way any contamination of mains water by water from the heating system is avoided.

Claims

1. Apparatus for connecting a fluid source to a fluid user system, the apparatus comprising a nonreturn valve unit, a flow regulator, and pipework for connecting the valve unit and the regulator, the valve unit allowing fluid flow to the fluid user system but preventing reverse fluid flow from the user system to the fluid source.

2. Apparatus according to claim 1 in which the fluid source is a mains water supply, and the fluid user system is a closed water system.

3. Apparatus according to claim 1 or claim 2 in which the pipework comprises flexible tubing.

4. Apparatus according to claim 1, 2 or 3 in which the connection between the pipework and the non-return valve unit is a non-permanent push-fit connection.

5. A non-return valve unit for use when pressurising or re-pressurising a closed fluid system from a pressurised fluid source, the unit comprising an inlet section adapted for connection to a filling pipe, an outlet section adapted for connection to the fluid user system, a central section having a through bore communicating with corresponding bores in the inlet and outlet sections to provide a common fluid passageway, and at least one non-return valve disposed along the common passageway, the valve or valves permitting flow from the inlet to the outlet but preventing flow in the reverse direction.

6. A valve unit according to claim 5 in which the inlet section comprises a housing having a through bore with a tapered first section providing a push-fit for the filling pipe.

7. A valve unit according to claim 6 in which the angle of the taper lies between 30 and 50 relative to the longitudinal axis of the bore, the diameter of the bore progressively narrowing from an initial value approximately equal to the diameter of the filling pipe.

8. A valve unit according to claim 7 in which the length of the tapered section is in the range of 1.8 to 2.0 cm.

9. A valve unit according to any one of the claims 6-8 in which the tapered first section opens into a second section of uniform cross-section communicating with the through bore in the central section.

10. A valve unit according to any one of the claims 5-9 in which two of the non-return valves are disposed in series with one another along the common passageway, each non-return valve comprising a valve stem extending axially along the passageway with respective flared heads cooperating with respective valve seats such that the passageway is blocked when at least one of the valves is seated.

11. A valve unit according to claim 10 in which each valve stem is fitted with a sealing ring at the base of the flared head, the sealing ring being resiliently urged against the respective valve seat to close the valve and seal the passageway.

12. A valve unit according to claim 11 in which each valve stem is oriented with its flared head downstream relative to the direction of flow from the inlet to the outlet, the upstream end of the respective stems each being enlarged to present substantial resistance to the flow of fluid along the passageway whereby each stem is axially displaced against its resilient bias to open the valve when fluid at the pressure of the fluid source is introduced through the inlet.

13. A valve unit according to any one of the claims 5-12 in which the outlet section includes an external screw thread for connection with a mating thread at the inlet of the fluid user system.

14. A valve unit according to any onetof the claims 5-13 in which the inlet section and the outlet section are each releasably coupled to the central section.

15. A valve unit according to claim 14 in which each of the said couplings is a screw threaded coupling.

16. Apparatus according to claim 1 in which the nonreturn valve unit comprises a valve unit according to any one of the claims 5-15.

17. Apparatus for connecting a fluid source to a fluid user system, the apparatus being substantially as herein described with reference to the accompanying drawings.