US3670760A

US3670760A - Backflow preventer

Info

Publication number: US3670760A
Authority: US
Inventors: James Butcher; Richard G Gyllstrom; William Doyle Lamb
Original assignee: A W Cash Valve Manufacturing Corp
Current assignee: A W Cash Valve Manufacturing Corp
Priority date: 1970-08-13
Filing date: 1970-08-13
Publication date: 1972-06-20
Anticipated expiration: 1989-06-20
Also published as: CA929821A

Abstract

A backflow preventer for preventing reverse water flow having as a part thereof a transverse wall between inlet and outlet water passages and with a valve disc in the form of an annular member mounted to be resiliently urged against said transverse wall and block a series of circularly disposed flow passages at all times except when normal water flow occurs through the backflow preventer. The valve disc is simply constructed of a resilient material in planar form and is mounted to be dished and urged against said transverse wall for seating engagement therewith.

Description

United States Patent Butcher et al.

[451 June 20, 1972 [54] BACKFLOW PREVENTER [72] Inventors: James Butcher, Oreana, 111.; Richard G. Gyllstrom, St. Cloud, Minn.; William Doyle Lamb, Decatur, Ill.

[73] Assignee: A; W. Cash Valve Manufacturing Corporation [22] Filed: Aug. 13, 1970 21 Appl. No.: 63,560

[52] 11.8. C1 ..l37/218, 137/5253 [51] Int. Cl ..Fl6k 45/00 [58] FieldofSearch ..137/217,218, 525.3

[5 6] References Cited UNITED STATES PATENTS 2,997,054 8/1961 Woodford 137/218 3,207,171 9/1965 Kryman ..l37/2l8 3,303,800 2/1967 Young ...l37/2l8 X 3,270,771 9/1966 Morgan et a1. ...l37/525.3 2,033,467 3/ 1936 Groeniger 137/21 8 X Primary Examiner-R0bert G. Nilson Attorney-Hofgren, Wegner, Allen, Stellman & McCord [57] ABSTRACT 8 Claims, 4 Drawing Figures BACKFLOW PREVENTER BACKGROUND OF THE INVENTION This invention pertains to a backflow preventer wherein normal water flow to a hose or the like can occur but reverse flow back to the supply main is prevented through the provision of a simply constructed valve disc associated with other structure which is inherently self-sealing against reverse flow.

This general type of device is known in the prior art and the general type of construction is shown in US. Pat. Nos. 2,322,631; 2,875,776; 2,898,835; 2,997,054; 3,023,767; and Re. 26,235. All of these known devices rely on a form of valve element wherein the element has a series of cross slits forming a plurality of independent valve elements which in normal water flow will tend to restrict the flow. These plural valve elements appear to be necessary to make certain that the discs returns to its seated position and such device can only be effective when all of the independent valve element sections return to seated position. Return to seated position would appear to require a fluid pressure on the elements urging them to seated position.

As distinct from this prior art, applicants have provided a construction wherein a simple annular disc is usable and which will not restrict normal flow and further which is mounted for self-sealing action in a simple manner and without reliance upon the return of a number of independent valve elements to seated position.

SUMMARY An object of this invention is to provide a new and improved backflow preventer of a simple economical construction and which provides more reliable operation than the devices known in the prior art.

Another object of the invention is to provide a backflow preventer utilizing a simple annular disc of rubber-like material which is mounted in association with the body parts of the backflow preventer whereby it is deflected against a transverse wall to seal off flow openings in said wall but which permits normal flow of water through the flow openings while at all other times being self-sealing against the wall to prevent backflow.

A further object of the invention is to provide a backflow preventer as defined in the preceding paragraph wherein the construction embodies a body and an adapter with the transverse wall formed on one of said parts and having the series of flow openings formed in said transverse wall in a circular disposition about a central solid section of the wall, and the annular valve disc is mounted at its periphery on a sloped flange which dishes the disc toward the transverse wall to impart forces urging the inner periphery of the valve disc against the transverse wall to seal off the flow openings and with normal flow deflecting the valve disc to a non-obstructing position and into position to close off a series of air relief holes which are normally open to atmosphere when the valve disc is seated against the transverse wall.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is an elevation of the backflow preventer shown in association with a water supply connection, such as a sill cock, and with a hose;

FIG. 2 is a vertical section of the backflow preventer taken generally along the line 22 in FIG. I and showing the valve disc in normal seated position;

FIG. 3 is a plan section taken generally along the line 3-3 in FIG. 2; and

FIG. 4 is a plan section taken generally along the line 4--4 in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT The backflow preventer is formed of two primary parts including a body and an adapter 11. The assembly in normal use is fitted to a water supply source, such as a sill cock l2, and flow is to a hose or the like having a coupling 16.

The body 10 has a tubular extension 20 defining a central passage 21 and is externally threaded at 22 to threadably receive the coupling 16 of the hose. The body 10 has a central recess communicating with the central passage 21 and sur' rounded by a raised annular rim 25. T A series of air relief holes 26 are formed in the body surrounding the tubular extension 20 and connect the central recess with atmosphere.

The adapter part 11 of the backflow preventer has a tubular section with an inlet 30 having internal threads, as indicated at 31, to thread onto the sill cock 12 or other connection and with a reduced portion of the adapter having a transverse wall 35 having a series of circularly disposed flow openings 36 disposed around a solid central section 37 of the transverse wall.

Nomial water flow to the inlet 30 passes through the flow openings 36 to the central recess of the body 10 and to the outlet defined by the central passage 21 of body 10.

A valve disc is associated with the transverse wall 35 to permit normal flow through the flow openings 36 while preventing backflow therethrough. This valve disc is in the form of an annular disc 40 having an inner periphery 41 and an outer periphery 42. The valve disc is formed of resilient rubber-like material and in one particular embodiment more specifically, is formed of neoprene 3376 as supplied by Minnesota Rubber wherein the material has a durometer hardness of 40 on Scale A. The planar valve disc is mounted between the body 10 and adapter 11 to be upwardly dished whereby the inner periphery 41 thereof, is in normal usage, urged against the transverse wall central part 37 and with the internal opening of the disc being less than the diameter of the circular disposition of the openings 36 whereby the flow openings are sealed as shown in FIG. 2.

This dished mounting is achieved by mounting the outer periphery 42 of the valve disc on an upwardly sloped annular flange 45 formed within the body 101 and with the opposite side of the outer periphery 42 of the disc engaged by a metal ring 46. With the reduced section of the adapter 11 including the transverse wall 35 press-fitted into the annular rim 25 of the body 10, the ring 46 is pressed against the outer periphery of the disc 42 which is seated against the upwardly sloped annular flange 45 whereby the disc is deflected from its planar condition to the upwardly dished configuration shown in FIG. 2. The air relief holes 26 in the body 10 underlie the valve disc whereby when the disc moves downwardly from the upwardly dished position, shown in FIG. 2, as caused by normal water flow conditions, the disc closes off the air relief holes 26.

With no water flowing through the backflow preventer, the annular disc 40 is seated against the transverse wall 35 closing off communication of the central passage 21 with the flow openings 36 and permitting free air passage through the air relief holes 26. With normal water flow through the backflow preventer, the valve disc 40 is deflected away from the flow openings 36, allowing water flow therethrough and through the central opening of the valve disc to the hose. As the valve disc 40 deflects away from the transverse wall 35, it deflects downwardly and covers the air relief holes 26. As the primary water supply is cut off, the valve disc 40 inherently returns to its normal position shown in FIG. 2 sealing the flow openings 36 from the outlet of the backflow preventer and opening the air relief holes 26 to atmosphere which allows entrapped water to drain through said holes.

If during normal operation the primary water supply is cut off allowing water to drain back into the main line, a vacuum could be created in the system and with the hose having its end in a pool of stagnant or contaminated water, this water could be drawn into the water system by the vacuum. This cannot occur with the backflow preventer because the disc 40 inherently returns to its seated position shown in FIG. 2 which is further caused by the vacuum tightly sealing the disc against the transverse wall 35 and opening the air relief holes 26 to at' mosphere to thus break the vacuum.

The valve disc 40 has an integral tab 50 extending downwardly therefrom, as shown in FIG. 2, and accessible through the central passage 21 whereby the valve disc 40 can be deflected from its closed position in order to drain the sill cock 12 or other flow connection for the backflow preventer.

Additional parts shown are a conventional hose washer 51 fitted in the adapter 11 and a set screw 52 threaded through the adapter 11 for locking the backflow preventer onto a sill cock or faucet.

With the construction disclosed herein, a simple annular valve disc of rubber-like material can be utilized to fit into the backflow preventer with a particular mounting for deflection thereof to an upwardly dished configuration for urging the disc to a sealing relation with associated structure and wherein the valve disc moves to a flow-permitting position and permits flow without restriction through the central opening thereof. Any time that the normal flow conditions terminate, the valve disc inherently returns to sealing position.

We claim:

1. A backflow preventer comprising a body having a central passage with an externally threaded section for connection to a hose and an annular raised rim surrounding a recess, a series of air relief holes connecting said recess with the exterior of the body, an adapter having an internally threaded section to fit onto a water supply line, a reduced portion of said adapter including a transverse wall fitted into said recess, a series of circularly disposed flow openings in said transverse wall arranged to leave a solid central portion of said wall, an annular disc between the adapter and body, and means on said body engaging the underside of said disc at the outer periphery thereof to urge the disc upwardly to be pressed against said transverse wall and close off communication between said flow openings and said central passage whereby normal flow of water will press the disc away from the flow openings to permit flow to said central passage and cause the disc to block the air relief holes.

2. A backflow preventer as defined in claim 1 wherein said means engaging the underside of the annular disc includes an upwardly inclined seating flange on said body and a ring on the opposite side of the disc with said ring pressed against the disc by assembly of the adapter and body with the reduced portion of the adapter fitted into the annular raised rim of the body.

3. A backflow preventer as defined in claim 2 wherein said annular disc is of rubber-like resilient material.

4. A backflow preventer as defined in claim 3 wherein said disc is of neoprene or the like.

5. A backflow preventer as defined in claim 2 including means integral with said disc and extending into said central passage for manual engagement to flex said disc and uncover said flow openings for drainage of water from said adapter.

6. A backflow preventer having inlet and outlet water passages in line and separated from each other by a transverse wall, said transverse wall having a series of circularly disposed flow openings surrounding a central solid portion of said wall, an annular valve disc of resilient material coacting with said flow openings to permit water flow from the inlet water passage to the water outlet passage but preventing reverse flow, said valve disc being formed as a planar member, and means on said body engaging the underside of said disc at the outer periphery thereof to urge the disc upwardly to press against said transverse wall with the inner periphery of the disc engaging the wall internally of the circularly disposed flow openings to seal off said flow openings, whereby normal water flow will move the disc away from the transverse wall and the water can flow through the central opening of the disc to the outlet water passage with the disc returning to its seat upon termination of flow.

7. A backflow preventer as defined in claim 6 wherein a series of air relief holes are provided at the opposite side of the valve disc with the disc closing off said holes during normal water flow conditions, said holes being open to atmosphere when the disc is pressed against the transverse wall.

8. A backflow preventer as defined in claim 6 wherein said disc is ofa resilient rubber-like material and said means on the body includes a sloped annular surface at a distance from said transverse wall which causes the dlShlflg of the disc toward the transverse wall.

Claims

8. A backflow preventer as defined in claim 6 wherein said disc is of a resilient rubber-like material and said means on the body includes a sloped annular surface at a distance from said transverse wall which causes the dishing of the disc toward the transverse wall.