AU702623B2

AU702623B2 - Tap with backflow restriction device

Info

Publication number: AU702623B2
Application number: AU71893/96A
Authority: AU
Inventors: James Leslie Raymond Oyston
Original assignee: QUEENSLAND PLUMBING Pty Ltd
Current assignee: QUEENSLAND PLUMBING Pty Ltd
Priority date: 1995-11-22
Filing date: 1996-11-21
Publication date: 1999-02-25
Anticipated expiration: 2016-11-21
Also published as: AU7189396A

Description

THIS INVENTION relates to a tap with a backflow re striction device.

The term "tap" shall be used throughout the specification to also include faucet, cock, stopcock and the like.

To prevent the contamination of reticulated water, a backflow restriction device must be either provided between, or incorporated into, the tap and any equipment to which it is connected.

For example, a restriction device must be provided to prevent the flow i* of chemicals from a garden sprayer to the reticulated water supply when the tap is turned off. The Standards require that any liquid under pressure downstream of the tap must be bled to atmosphere (and possibly collected in a sump).

There have been a number of proposals for taps incorporating backflow restriction devices and/or backflow restriction I:itt: 15 devices to be fitted to existing taps, but these have generally proved complex and expensive to manufacture. A further disadvantage with e many of these known units is that a volume of the liquid is bled to atmosphere every time the tap is turned on and this is clearly a waste.

It is an object of the present invention to provide a tap with a restriction device which provides effective protection against backflow.

It is a preferred object to provide such a tap where the restriction device does not bleed liquid to the atmosphere when the tap is turned on.

It is a further preferred object of the present invention to provide a tap where the restriction device may be removed for the ease of manufacture and assembly, and for any maintenance, if required.

Other preferred objects of the present invention will become apparent from the following description.

In a broad aspect, the present invention resides in a tap (as hereinbefore defined) having a backflow restriction device, including: a body having a fluid flow chamber connected to an inlet passage; 15 a flow valve operable to control the flow of liquid from the inlet passage to the fluid flow chamber; a first valve seat interconnecting the flow chamber to a first chamber; a second valve seat interconnecting the first chamber to a second chamber; pressure bleed vent(s) interconnecting the second chamber to atmosphere; the flow port(s) interconnecting the first chamber to an outlet passage; and restriction valve means having a first piston means to selectively connect the first chamber to the flow chamber to allow liquid to flow from the inlet passage to the outlet passage, and a second piston means to selectively connect the first chamber to the second chamber to enable liquid under pressure in the outlet passage to be bled to atmosphere.

:Preferably the inlet passage is connected to a reticulated 10 water supply or other liquid supply source.

Preferably the flow valve is a jumper valve, rotary valve or other like valve operable by a handle to control the flow rate through the tap. Where the flow valve is a jumper valve, a flow valve seat is provided intermediate the inlet passage and the flow chamber, coaxial with the bib.

Preferably the restriction valve means is provided S"perpendicularly to the inlet passage and is preferably coaxial with the outlet passage.

Preferably the first piston means is of a larger diameter than the second piston means, and the valve means incorporates a stem or shank slidably mounted in a bore in a removable body of the backflow restriction device.

Preferably spring means urge the first piston means into engagement with the first valve seat.

Preferably a plurality of flow ports are provided in the restriction device body, parallel to, but spaced around, the axis of the outlet passage.

Preferably the bleed ports extend radially through the restriction device body from the second chamber.

Preferably a peripheral flange on the body of the tap extends around, but is spaced from, the outer ends of the bleed ports i10 to provide a shroud therefor.

To enable the invention to be fully understood, a eool preferred embodiment will now be described with reference to the accompanying drawings in which: FIG 1 is a part-sectional side view where the restriction oe oI 15 device is arranged to vent pressurised liquid in the outlet passage to atmosphere; FIG 2 is a sectional view taken on LINE 2-2 on FIG 1; and FIG 3 is a part-sectional view, corresponding to FIG 1, where the restriction means is arranged to allow flow of liquid from the inlet passage to the outlet passage.

The tap 10 has a body 11 with an inlet passage 12 connectable to a liquid supply (eg. a reticulated water mains) by a screw-threaded fitting (not shown). A flow chamber 13 in the body

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11 is selectively connected to the inlet passage 12 by a jumper valve 14 adapted to engage a flow seat 15. The jumper valve 14 is mounted on the spindle 16 of a bib 17 and is controlled by a T-shaped handle 18.

A first chamber 19 is formed in part by a lateral extension 19A on the tap body 11, and the first chamber 19 is interconnected to the flow chamber 13 by a first valve seat The flow restriction device 21 has a body 22 screwthreadably engaged, and sealed to, the lateral extension 19A of the 10 tap body 11 and its inner end co-operates to form the first chamber 19.

A plurality of flow ports 23 extend through the restriction device body 22 to interconnect the first chamber 19 with the outlet passage 24. The outlet passage 24 may be connected, eg. to a 15 garden sprayer, via a hose with a screw-threaded fitting (not shown).

A second chamber 25, of reduced diameter relative to the first chamber 19, is connected to the first chamber 19 via a second valve seat 26.

A plurality of bleed ports 27 extend radially from the second chamber 25 and are open to the atmosphere, the outer ends of the bleed ports 27 being enclosed by a shroud 28 on the lateral extension 19A of the tap body 11.

A restriction valve assembly 29 has a shank 30 slidably received in a bore 31 coaxial with the restriction device body 22, and a coil compression spring 32 urges the restriction valve assembly 29 towards the first seat The restriction valve assembly 29 has a first piston 33 spaced from a second piston 34, of reduced diameter, by a peripheral flange 35. The pistons 33, 34 are provided with respective seals 36, 37 to sealably engage the first and second seats 20, 26 respectively.

i The operation of the tap 11 and the backflow restriction device 21 will now be described.

As shown in FIG 1, when the jumper valve 14 is seated on seat 15 to prevent the flow of liquid through the tap 10, the compression spring 32 urges the first valve 33 into sealing engagement with the first seat 9 15 As the first and second chambers 19, 25 are interconnected, any pressurised liquid in the outlet passage 24 may 9* 9 flow through the flow ports 23 into the first chamber 19, then through the second chamber 26, and out the bleed ports 27 to atmosphere.

None of the pressurised fluid can enter the flow chamber 13, and thereby the inlet passage 12, to the liquid source.

When the flow valve jumper 14 is lifted from the seat the fluid pressure on the top of the first piston 20 will exceed any pressure in the first chamber 19 and the restriction flow valve 8 assembly 29 will move against the compression spring 32, so that the second piston means 34 engages the second seat 26 before the first piston 33 is disengaged from the first valve seat 20. At this intermediate point, there is no fluid flow through the tap 10 as both the flow ports 23 and the bleed ports 27 are isolated from the flow chamber 13.

As the restriction valve assembly 29 continues to move, the first piston 33 is disengaged from the first valve seat 20 and liquid 9. 9e flows from the flow chamber 13 to the first chamber 19, and then out through the flow ports 23 to the outlet passage 24.

When the liquid flow is shut off by reseating flow jumper valve 14 on seat 15, the compression spring 32 will move the first piston 33 into engagement with the first valve seat 20 before the second piston 34 is disengaged from the second valve seat 26, to 99*9*9 9 15 prevent any backflow of liquid under pressure from the outlet passage 24 to the flow chamber 13. As the restriction flow valve assembly 29 *9 moves to the position shown in FIG 1, the first chamber 19 and second chamber 25 will again be in communication to allow the pressurised fluid to be vented to atmosphere via the vent ports 27.

For ease of manufacture, assembly and maintenance, it is preferable that the flow restriction device 21 has a body 22 releasably detachable from the tap body 11.

9 It will be readily apparent to the skilled addressee that the first valve seat 20 may be incorporated in the backflow restriction device 21 and the device 21 be screw threadably, or otherwise engaged, in a suitable lateral passage or port in the tap body 11.

With the embodiment as herein described and illustrated, it will be readily apparent to the skilled addressee that when the tap is operated to allow the flow of liquid from the inlet passage 12 to the outlet passage 24, no liquid is lost or wasted to the atmosphere; i* and the only liquid which is vented to the atmosphere is any liquid which is under pressure in the outlet passage when the flow jumper valve 14 is closed.

Various changes and modifications may be made to the ;a embodiment described and illustrated without departing from the scope of the present invention.

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The claims defining the invention are as follows: 1. A tap (as hereinbefore defined) having a backflow restriction device, including: a body having a fluid flow chamber connected to an inlet passage; a flow valve operable to control the flow of liquid from the inlet passage to the fluid flow chamber; a first valve seat interconnecting the flow chamber to a first chamber; a second valve seat interconnecting the first chamber to a second chamber; pressure bleed vent(s) interconnecting the second chamber to atmosphere; the flow port(s) interconnecting the first chamber to an 15 outlet passage; and restriction valve means having a first piston means to 9 selectively connect the first chamber to the flow chamber and allow liquid to flow from the inlet passage to the outlet passage, and a second piston means to selectively connect the first chamber to the second chamber to enable liquid under pressure in the outlet passage to be led to atmosphere.

2. A tap as claimed in Claim 1 wherein:

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Claims

3. A tap as claimed in Claim 1 or Claim 2 wherein: the flow valve is a jumper valve, rotary valve or other like valve operable by a handle to control the flow rate through the tap.
4. A tap as claimed in Claim 3 wherein: when the flow valve is a jumper valve, the flow valve set is provided intermediate the inlet passage and the flow chamber, coaxial with the bib.
5. A tap as claimed in any one of Claims 1 to 4 wherein: the restriction valve means is provided perpendicularly to the inlet passage and is preferably coaxial with the outlet passage. o 6. A tap as claimed in any one of Claims 1 to 5 wherein: the first piston means is of a larger diameter than the 15 second piston means, and the valve means incorporates a stem or shank slidably mounted in a bore in a removable body of the backflow S restriction device.
7. A tap as claimed in Claim 6 wherein: spring means urge the first piston means into engagement with the first valve seat.
8. A tap as claimed in any one of Claims 1 to 7 wherein: 9 *9 .9 .9 *9*9
9. 9 V .9 V 12 a plurality of flow ports are provided in the restriction device body, parallel to, but spaced around, the axis of the outlet passage. 9. A tap as claimed in any one of Claims 1 to 8 wherein: the bleed ports extend radially through the restriction device body from the second chamber. A tap as claimed in Claim 9 wherein: a peripheral flange on the body of the tap extends around, but is spaced from, the outer ends of the bleed ports to provide a shroud therefor.
11. A tap (as hereinbefore defined) substantially as hereinbefore described with reference to the accompanying drawings. DATED this twenty-first day of November 1996. QUEENSLAND PLUMBING PTY LTD By its Patent Attorneys FISHER ADAMS KELLY I 13 ABSTRACT A tap (10) has a backflow restriction device, where a first piston (33) selectively opens a passage (20) between a flow chamber (13) and a first chamber and a smaller second piston (34) selectively opens the first chamber (19) and second chamber When the tap (10) is turned off, water in the outlet passage (24) is precluded from flowing back through the first chamber (1 9) to the flow chamber (13) by the first piston (33) but can enter 0: the second chamber (25) and flow out through bleed ports (27). 9* S 9. g