AU618862B2 - Reduced pressure zone valve - Google Patents

Description

618862 COMMONWEALTH OF AUSTRALIA Patents Act 1952 S Name of Applicant Address of Applica.nt Actual Inventor(s) Address for Service SAddress for Service i QUEENSLAND PLUMBING PTY LTD 22 Prospect Street, Fortitude Valley Queensland 4006 Australia DONALD HARDIE SMITH GRANT ADAMS COMPANY, Patent Trade Mark Attorneys, Level 9 NATIONAL MUTUAL CENTRE 144 Edward Street, BRISBANE. QUEENSLAND. 4000

AUSTRALIA.

.44 .4 COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED: "REDUCED PRESSURE ZONE VAIvE" The following statement is a full description of the invention including the best method of performing it known to the applicant.

I I THIS INVENTION relates to a reduced pressure zone valve.

In many water supply installations it is required to instal reduced pressure zone valve assemblies for the prevention of back-syphonage and back pressure flow such as may occur when a water main is fractured or disconnected, with the possibility that the consequent drop in pressure may draw contaminated water into the main.

The general object of the Inavention is to provide, for this purpose, a reduced pressure zone valve which is particularly efficient and positive in operation. Other objects achievable in preferred embodiments of the invention are to provide such a valve S 15 assembly which is particularly simple and economical in construction and durable and trouble-free in use.

With the foregoing and other objects in view, the invention resides broadly in a reduced pressure zone valve assembly for connection between a water supply line from a water main and a water delivery line including: ia non-return valve connected, in use, into the supply line; a hydraulic cylinder; a first water inlet to the hydraulic cylinder, connected to the supply line up-stream of the non-return valve; a second water inlet to the hydraulic cylinder, connected to the supply line down-stream of the non-return valve; a piston in the hydraulic cylinder bet.7.en the first and second water inlets thereto divlding the cylinder into first and second ernds; an outlet from the hydraulic cylinder to the water delivery line at the same second end of the I cylinder as is the second water inlet; a passage from the hydraulic cylinder at the second end to atmosphere; and a valve connected to the piston to close the said passage when the piston is acted on by water under pressure in the supply line, and for opening the said passage when the pressure of water in the supply line is reduced below that at ~he outlet.

Other features of the invention will become apparent from the following description.

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II I II In order that a preferred embodiment of the invention may be readily understood and carried into practical effect, reference is now made to the accompanying drawings wherein:- FIG. 1 is a partly broken-away side elevational view of a reduced pressure zune valve according to the invention, in its normal or inoperative position and FIG. 2 is a similar view of the valve in its S 10 operative arrangement preventing back-flow of water.

K The reduced pressure zone valve assembly shown in the drawings is connected between a water supply line from a water mains system and a water delivery pipe 11 conducted into premises required to have the reduced 15 pressure zone back-flow prevention device installed.

The valve assembly between the water supply line 10 and the delivery pipe 11 includes, connected in 000 series, a T-piece connector 12, a first non-return valve 0 13, a valve chamber 14 and a second non-return valve 000 20 The non-return valves are of well-known type permitting free flow of water under pressure in the direction g o 0 indicated by arrows but preventing back-flow of the 004000 0water.

Fo7 the purpose of testing the assembly, as may from time to time be required, test-valves 16 are connected to the first and second non-return valves 13 and 15. A third similar test-valve (not shown) may also be connected to the valre chamber 14.

The valve chamber 14 interposed between the first and second non-return valves has a cylindrical body 17 with its axis perpendicular to the axes of the inlet and outlet pipes 10 and 11, and sealed top and bottom end caps 18 and 19. The outlet of the first nonreturn valve 13 communicates with the valve chamber 14 by way of a chamber inlet 20 leading perpendicularly into the middle of the body 17 a chamber outlet 21 coaxial with the inlet 20 being connected to the second non-return valve The branch 22 of the T-piece connector 12 is j connected by a by-pass pipe 23 to an inlet 24 leading coaxially through the top end cap 18 of the chamber 14.

i A drain outlet passage 25 is formed through the bottom end cap 19 of the chamber and has a valve seating 26 about its upper end. A vermin-proof disc 27 is fixed in the outlet passage 25 below the valve seating 26.

i1 0 Within the upper part of the chamber 14 is a t piston 28 on a downwardly extending stem 29 having on iI its lower end a valve 30 which, when the piston is

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fi depressed or retracted as shown in FIG. 1, seats upon 1 the valve searing 26 to close the drain outlet passage 15 25; and when in raised or extended position, as shown in FIG. 2, unseats the valve 30 to open the drain outlet passage.

A fairly light helical spring 31, its lower end on the bottom end cap 19 about the seating 26, its upper end engaging a flange 32 about the stem 29, biases I the piston 28 to its raised position. This spring is such that it does no more than counterbalance the piston and its associated parts.

In use, water under pressure will flow freely ii 25 through the valve assembly, from the water supply line i 10 to the delivery pipe 11 whenever water Is drawn from any of the tap outlets of the premises supplied from the water main. The piston 28 is in a state of equilibrium J: within the valve chamber 14 with water under mains 30 pressure above and below it, and the valve 30 remains in i its closed position on the seating 26.

These conditions apply unless or until there is a drop in the mains pressure so that water can return from the top of the valve chamber 14 through the by-pass 23 by-passing the first non-return valve 13 which prevents return of water under pressure from below the piston. The pressure differential causes the piston to rise, as shown in FIG. 2, unseating the valve 30 so that the water contained in the cylinder below the piston can escape to waste through the outlet passage 25. The device, then maintains a reduced pressure zone between the incoming mains pressure on one side of the valve chamber 14 and the mains pressure on the opposed side of the valve chamber. In the event of any leakage from the second non-return valve 15, any returning water passes to waste. When normal mains pressure is resumed the piston 28 is driven immediately to its normal position shown in FIG. 1, bringing the valve 30 to closed Sposition or it seating 26.

Reduced pressure zone valves according to the 15 invention will be found to be very effective in achieving the objects for which they have been devised.

It will, of course, be understood that the particular embodiment of the invention herein described and Sillustrated may be subject to many modifications of 20 constructional detail and design, which will be readily apparent to persons skilled in the art, without

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departing from the spirit and scope of the invention hereinafter claimed.

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Claims (5)

1. A reduced pressure zone valve assembly for connection between a water supply line from a water main and a water delivery line including: a non-return valve connected, in use, into the supply line; a hydraulic cylinder; a first water inlet to the hydraulic :jcylinder, connected to the supply line up-stream of the non-return valve; a second water inlet to the hydraulic I. cylinder, connected to the supply line down-stream of the non-return valve; a piston in the hydraulic cylinder between e 15 the first and second water inlets thereto dividing the i cylinder into first and second ends; an outlet from the hydraulic cylinder to the 'I water delivery line at the same second end of the cylinder as is the second water inlet; S: 20 a passage from the hydraulic cylinder at the second end to atmosphere; and ii' a valve connected to the piston to close the said passage when the piston is acted on by water Sunder pressure in the supply line, and for opening the said passage when the pressure of water in the supply line is reduced below that at the outlet.

2. A reduced pressure zone valve assembly according to Claim 1 wherein: the outlet from the hydraulic cylinder is connected to the water delivery line by way of a second non-return valve.

3. A reduced pressure zone valve assembly according to either of the preceding claims wherein: the hydraulic cylinder is substantially vertical; J- -I 0 4 I .c <3 Ii A. the first water inlet leads into an upper part of the hydraulic cylinder above the piston; the second water inlet leaes radially from a middle part of the hydraulic cylinder below the piston; and the piston is movable in the hydraulic cylinder above the second water inlet and the water outlet thereof.

4. A reduced pressure zone valve assembly according to Claim 3 wherein: the passage from the hydraulic cylinder to atmosphere is at a position below the piston and it is normally closed by the piston mounted valve which is on a stem depending from the piston; the piston being biassed upwardly by a counterbalancing spring.

5. A reduced pressure zone valve assembly substantially as herein described with reference to the accompanying drawings. DATED this fifteenth day of October 1991. QUEENSLAND PLUMBING PTY. LTD., By its Patent Attorneys, GRANT ADAMS COMPANY. L