US2675823A - Backflow preventer - Google Patents

Description

April 20, 1954 J. LANGDON BACKFLOW PREVENTER Filed Sept. 7, 1949 Inventor fia a Patented Apr. 20, 1954 UNITED STATES PATENT OFFICE BACKFLOW PREVENTER Jesse D. Langdon, Long Beach, Calif.

Application September 7, 1949, Serial No. 114,418

9 Claims.

This application is a continuation in part of Ser. No. 735,733, March 28, 1949, now abandoned.

The invention relates to check valves particularly for use with devices to prevent a backfiow of contaminated fluid into the outlet of a device having its inlet end connected to a source of fluid supply.

The primary purpose of the invention is to provide a double acting check valve mechanism for closing air vents in a casing having inlet and outlet ends, and to prevent backflow thru the double valve when a greater pressure exists at the outlet end.

Another object is to provide a check valve having more than one check valved opening cooperably combined in a single unit.

Another object is to provide a check valve unit having multiple chamber means found within a flexible wall surrounding the chamber means whereby a greater initial pressure can be held in one chamber than in another chambered portion of the device.

Another object is to devise means for changing the differential of pressure between the multiple chambers of the instant type of device.

A'further object is to maintain a greater pres" sure in that portion of a flexible tubular check valve member that overlies the inside of an adjacent perforated casing wall area to thereby minimize aspiratory noise therethru caused by the entrainment of air by a stream of water passing thru the check valve and the casing.

Other and further objects and purposes will appear during the progress of the specification.

Only one form of reduction to practice is illustrated by the drawing and it is specifically understood that reduction to practice shown may be changed within that anticipated by the specification and Within the scope of the claims.

The figure of the drawing illustrates in vertical median section, a valve organization as embodied in the invention.

The drawing shows a valve member I made of distortable material capable of returning to normal shape and having an inlet end 2 and an outlet end 3 with a preferably bell shaped valve member i; attached to a cage intervening between the inlet 2 and outlet 3 and formed by barred spider washer 5, secured in a groove G, provided circumierentially internally of the flange IF which is extended radially outward of the inlet end 2 of the member I, the latter inserted into the casing I and resting on the internal annular shoulder portion 6 of easing I which is provided with thread means IT for pressure sealing and coupling the device to a'source of pressure fluid supply.

The casing I is provided with vents V, thru the wall thereof. The casing I being coupled to a source of pressure fluid supply and liquid under pressure flowing thru the valve member i, the bell washer l inserted into and encased by the flexible sleeve portion of member I, surrounding bell 4 forms a chamber 4C which causes the member I to be bulged radially outward under the influence of internal pressure as shown by dotted lines B, closing the vents V. The flowing liquid forms a circumferential slit opening BS between the lower peripheral extremity of bell 4. The inside wall of member I permits the passage of pressure fluid thru slit BS into another chamber lC defined by the member I which has the transverse diaphragm like outlet end 3 normally closed provided with a forwardly projecting lipped portion L which is slit at AS; the lipped portion L forming the opposite sides bordering the slit AS and normally touching one another to close the slit AS.

It will be noted that a comparatively large annular clearance space is provided between the wall of member I and wall of casing I which is closed by bulge B of sleeve I due to internal pres sure. The large clearance space is made practical without danger of leakage of internal pressure fluid thru the vents, due to internal pressure within member I being enhanced by the double bafile effect of bell 4 and closed end 3 of member I causing the same to expand against wall of casing 1 as at B.

The member I when in operation will normally retain liquid in the chambers both above and below the bell 4 as atmospheric pressure or other pressure exerted against the external closed portion of member I will close slit AS and compress Itahe Zvall of member I against the periphery of ell The drawing shows bell 3 as forming a baflle with an imperforate wall portion presenting a seating face interceding intermediate of the cage 5 and outlet end 3, of sleeve member I. The bell 4 is held in juxtaposition with the barred spider forming cage 5 and concentric to the flange IF and the wall of member I. The lower edge of bell 4 is concomitant with the surrounding wall of sleeve member I made of deformable material. When external pressure is exerted against the exterior of member I the wall thereof is collapsed around bafiie 4 and the lip bordered slit end 3-L-AS is urged shut until such time as external pressure becomes great enough to overcome the resistance or" the lipped end L-AS of member I reversing the same thru the slit end 3 and into the chamber IC of member I. The forward face of bell d intercedes between the openings of cage and slit AS. The wall of member I will deform under external pressure, collapse and cause slit AS to be opened in a reverse direction. It is obvious that without bafile 4 the openings of cage 5 between the bars thereof would permit the lips of member i to be urged therethru by excessive external pressure and thereby permit backflow of pressure fluid thru sleeve member I.

Unless atmospheric or other pressure enters above inlet end 2 liquid in the chambers of member i can not be expelled. Further, if the assembly as shown were disconnected, being full of liquid, the normal tension of wall of member I against the periphery of the bell would hold a body of liquid in the chamber above bell 4 while the tension of lipped portion 3 of member I closing the slit AS would retain liquid in the lower chamber IC.

A bell-shaped washer '9 made of metal or other suitable rigid material retains the bell 4 in as sembled relationshipwith spider 5 by means of a rivet R or other suitable means.

When a'subatmospheric pressure exists at the inlet endi in the chamber 20 the member 5 is collapsed by atmospheric pressure against the periphery of bell li forming a check valve by the contact or bell member l with the wall of member 2 While slit AS is likewise closed by a subatrnos pheric pressure existing in chamber 30.

Having described the invention and the operation thereof, the-following claims are made:

1. A backflow preventer comprising a tubular sleeveinember having inlet and outlet ends and being made of deformable material capable resuming shape afterbeing deformed, the sleeve being providedwith-pressure sealing means for making a connection with a source of pressure fluid supply at the inlet end and having an imperforate sidewall portion between the two ends, a normally closed lip bordered slit outlet end forming a check valve, a flexible bell shaped member secured in concentric relationship to the inlet end and within the sleeve, the periphery of the bell projecting toward the sleeve wall and constituting a second check valve in combination with the surrounding wall of said sleeve whereby subatmospheric pressure within the inlet end above the bell will permit atmospheric'pressure to urge the sleeve wall inwardly against the periphery of the bell preventing ingress of pressure fluid toward the inlet end past the periphery of the bell, the normally closed lip bordered slit end of the sleeve being further compressed together by external pressure against the lipped end and providing addtional check valve means at the outlet end of said sleeve, resisting backflow of pressure thru the sleeve.

2. A deformable sleeve as defined by claim 1 inserted into a tubular casing having an inlet end and an outlet end, with vent means thru the casing wall between two ends, the pressure sealing means including juxtapositioned concomitant inlet ends of the casing and sleeve, the imperforate side wall of said sleeve overlying said vent means, internal pressure expanding said imperforate side wall against the casing wall closing said vents against egress'of pressure fluid, said bell washer forming a baflie to impede flow of pressure fluid thruthe sleeve and expand same against the casing wall, the normally closed lip bordered slit end forming a restricted outlet adapted to resist flow of pressure fluid thru said sleeve to further enhance the effects of internal pressure causing the expansion of said sleeve above said baffle against the casing wall to close said vents.

3. An article of manufacture comprising a sleeve member made of deformable material having a flanged inlet end, a normally closed slit restricted outlet end and an imperforate tubular wall between the ends, a caged support juxtapositioned across the inlet end and attached to a bafiie disposed concentrically within the imperiorate wall of the member surrounding said bafile, same dividing the inside of said sleeve member into two chambers and preventing the slit outlet end of the deformable member from being reversed thru said caged support by external pressure.

i. A device as defined by claim 3 wherein the concentrically disposed baiile is bell shaped and the peripheral edge of the bell juxtapositioned, extended toward, and concentric with the wall of the deformable sleeve member.

5. An article of manufacture as defined by claim 3 wherein the flange of the sleeve valve member forms a gasket extended radially outwardly of the inlet and adapted to form pressure sealing means for insertion between opposing faces of coupling means adapted to retain said sleeve member in a pressure sealed position interrupting between a source of fluid supply and the outlet end of a fluid conduit.

6. A backfiow preventer check valve unit, in cluding a tubular casing having inlet and outlet ends and being vented between the two ends, combined with a sleeve member having a flanged end concomitant with the inlet and being made of shape resuming deformable material, the inlet end of said casing-extended radially outwardly forming an annular shoulder supporting the flanged end of the sleeve the opposite end of the sleeve member provided with'a normally closed lip-bordered slit outlet passageway for pressure fluid, a cage having a rim juxtapositioned concomitant with the flange, a bafile depending from said rim and extending transversely of said sleeve intermediate of the two ends, said baille presenting a seating face toward the closed end of said sleeve member, said sleeve member being urge, toward said seating face by external pressure at such times as pressure internally or" said'sleeve is less than externalpressure thereagainst, the slit end of said sleeve member forming one check valve subject to being urged shut under one condition of external; pressure, a second check valve formed by the conjunction of the sleeve wall with said bafilewhereby in'the event of the slit end of the sleeve being inverted by excessive external pressure, the wall and the slit end of said sleeve urged against said baifie will'prevent reversal of the outlet end of said sleeve thrusaid and baokflow ofpressurefiuid thru the inlet end.

7. An article of' manufacture including in combination a casinghaving inlet and outlet ends, ports communicating withtatmosphere thru the casing wall between the two ends, the inlet end forming pressure scaled connecting means for a source of pressure fluid supply, together with a tubular sleeve valve member made or shape resumingdeformable material, one end extended into the inlet end of said casing, andtoward the outlet and overlying said ports, one end of the sleeve provided with'angannular shoulder concomitant with said inletiend of said casing, .21

cage of relatively rigid material juxtapositioned with said annular shoulder and means forming a baflle extended across the inside and intermediate of the ends of the sleeve, check valve means formed by the juxtaposition of said sleeve wall, and said baffle, a second check valve formed by that end of said sleeve that is toward the outlet end, same being inturned and bordering a slitted passage for pressure fluid, whereby abnormal internal pressure will be efiective to open both check valves and expand said sleeve to close the casing ports, abnormal external pressure acting to collapse said sleeve and urge the slitted end toward said bailie closing said outlet passage, under the efiects of further excessive external pressure.

8. A device as of claim 7 wherein the slitted end of the sleeve is lipped, same being urged against said baflle thereby preventing the slitted end from being opened by excessive external pressure and being completely reversed thru the cage openings.

9. A device as defined by claim 7 wherein the sleeve valve member is divided into two chambers located on oppoiste sides of the bafile, one chamber located on the inlet side with a second chamber located between the slitted end and said baffie, whereby in event of excess internal pressure reversing the lipped end of the sleeve member into the second chamber, said baffle interceding will prevent the lipped end from being urged thru the openings of the cage.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 127,038 Field May 21, 1872 155,668 Painter Oct. 6, 1874 280,212 Miles June 26, 1883 2,098,886 Safiord Nov. 9, 1937 2,113,615 Farmer Apr. 12, 1938 2,270,737 Langdon Jan. 20, 1942 2,322,631 v Groeniger June 22, 1943 2,371,449 Langdon Mar. 13, 1943 2,382,427 Langdon Aug. 14, 1945

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