Backflow preventer valve assembly

Claim 2

A backflow preventer valve assembly adapted to be mounted in a water line between the water main and a service pipe, which comprises: first and second check valves mounted in series relationship relative to each other and defining a zone therebetween, both of said check valves being oriented to permit flow of water from said main to said service pipe and to prevent flow of wAter from said service pipe to said main, wall means to define a diaphragm chamber, a diaphragm mounted sealingly across said diaphragm chamber and dividing the same into a first subchamber and a second subchamber, a bellofram, means to mount said bellofram and to cause one side thereof to be exposed to water pressure present in one of said subchambers, a valve seat through which water may drain from said zone at all times except when said seat is covered by a poppet, a poppet associated with said valve seat and movable between a closed position seated on said seat to block drainage of water therethrough, and an open position spaced from said seat and permitting drainage of water therethrough from said zone, means to connect said poppet to both said diaphragm and said bellofram whereby said poppet is actuated in response to pressures exerted on said diaphragm by water pressure present in said first and second subchambers, and in response to pressure exerted on said bellofram due to water pressure present in said one subchamber, resilient means to bias said poppet toward open position, means to transmit to said second subchamber the water pressure present in said zone, and means to transmit to said first subchamber the water pressure present on the upstream side of said first check valve.

Claim 3

The invention as claimed in claim 1, in which a piston is mounted in said bellofram, and in which said bellofram has an effective diameter substantially larger than the outer diameter of said piston.

Claim 4

The invention as claimed in claim 2, in which the effective diameter of said bellofram is different from that of said valve seat.

Claim 5

The invention as claimed in claim 3, in which the effective diameter of said bellofram is smaller than that of said valve seat, whereby to create a force tending to maintain said poppet seated firmly on said seat at all times except when there is an actual or incipient backflow condition.

Claim 6

The invention as claimed in claim 1, in which said valve seat has an apex edge at the outer portion thereof and adapted to sealingly engage said poppet, and in which said valve seat has a beveled surface extending inwardly from said apex edge and inclined away from said poppet.

Claim 7

The invention as claimed in claim 1, in which said poppet has an inclined surface provided thereon and which is located radially-inwardly from said seat when said poppet is seated thereon, the angle of incline of said surface being such that water passing between said seat and said poppet upon cracking of said poppet off said seat will strike said inclined surface and create a resultant force tending to move said poppet further away from said seat.

Claim 8

The invention as claimed in claim 1, in which said seat has a surface located adjacent said poppet and which is so shaped that flow of water between said surface and said poppet upon cracking of said poppet off said seat will not create any suction forces tending to draw said poppet back into engagement with said seat, and in which said poppet has an inclined surface provided thereon and which is located radially-inwardly from said seat when said poppet is seated thereon, the angle of incline of said surface being such that water passing between said seat and said poppet upon cracking of said poppet off said seat will strike inclined surface and create a resultant force tending to move said poppet further away from said seat.

Claim 9

The invention as claimed in claim 1, in which means are provided to vent to the ambient atmosphere the space on the other side of said bellofram.

Claim 10

A backflow preventer valve assembly adapted to be connected between a water main and a service pipe, which comprises: first and second check valves connected in series relationship relative to each other between said water main and said service pipe, both of said check valves being directed to permit flow of water from said main to said service pipe, and to prevent flow of water from said service pipe to said main, wall means to define a diaphragm chamber and a bellofram chamber, a diaphragm mounted sealingly across said diaphragm chamber, said diaphragm dividing said diaphragm chamber into a first subchamber which is relatively adjacent said bellofram chamber and a second subchamber which is relatively remote from said bellofram chamber, a bellofram mounted sealingly across said bellofram chamber, said bellofram dividing said bellofram chamber into a third subchamber which is relatively adjacent said diaphragm chamber and a fourth subchamber which is relatively remote from said diaphragm chamber, a piston mounted axially in said fourth subchamber and having a diameter substantially smaller than that of said bellofram chamber whereby a gap is defined around said piston between said piston and the wall of said bellofram chamber, said bellofram having a portion which extends into said gap in a direction away from said diaphragm chamber, and then reverse-bends back toward said diaphragm chamber, so that a reverse-bent portion is present in said gap, a valve seat provided in said second subchamber and communicating with a discharge opening to the ambient space, a poppet disposed in said second subchamber and seated on the side of said seat which is adjacent said bellofram chamber, resilient means to bias said poppet toward an open position spaced from said seat, means to connect said poppet to said diaphragm and to said bellofram and piston whereby said poppet is actuated in response to the forces acting on said diaphragm and said bellofram and also in response to the force exerted by said resilient means, means to cause the pressure present in said first subchamber to be present in said third subchamber, means to transmit to said first subchamber the water pressure present in said water main, and means to conduct water from said zone to said second subchamber whereby said water discharges through said seat to the ambient space when said poppet is spaced from said seat.

Claim 11

A backflow preventer valve assembly adapted to be connected between a water main and a service pipe, which comprises: first and second check valves connected in series relationship relative to each other between said water main and said service pipe, both of said check valves being directed to permit flow of water from said main to said service pipe, and to prevent flow of water from said service pipe to said main, wall means to define a diaphragm chamber and a bellofram chamber, a diaphragm mounted sealingly across said diaphragm chamber, said diaphragm dividing said diaphragm chamber into a first subchamber which is relatively adjacent said bellofram chamber and a second subchamber which is relatively remote from said bellofram chamber, a bellofram mounted sealingly across said bellofram chamber, said bellofram dividing said bellofram chamber into a third subchamber which is relatively adjacent said diaphragm chamber and a fourth subchamber which is relatively remote from said diaphragm chamber, a piston mounted axially in said fourth subchamber and having a diameter substantially smaller than that of said bellofram chamber whereby a gap is defined around said piston between said piston and the wall of said bellofram chamber, said bellofram having a portion which extends into said gap in a direction away from said diaphragm chamber, and then reverse-bends back toward said diaphragm chamber, so that a reverse-bent portion is present in said gap, a valve seat provided in said second subchamber and communicating with a discharge opening to the ambient space, a poppet disposed in said second subchamber and seated on the side of said seat which is adjacent said bellofram chamber, resilient means to bias said poppet toward an open position spaced from said seat, means to connect said poppet to said diaphragm and to said bellofram and piston whereby said poppet is actuated in response to the forces acting on said diaphragm and said bellofram and also in response to the force exerted by said resilient means, means to cause the pressure present in said first subchamber to be present in said third subchamber, means to transmit to said first subchamber the water pressure present in said water main, and means to conduct water from said zone to said second subchamber whereby said water discharges through said seat to the ambient space when said poppet is spaced from said seat.

Claim 12

The invention as claimed in claim 9, in which means are provided to vent said fourth subchamber to the ambient atmosphere.

Claim 13

The invention as claimed in claim 9, in which said resilient means is a spring which is mounted on the side of said bellofram chamber remote from said diaphragm chamber, said spring being associated with said means to connect said poppet to said diaphragm and to said bellofram and piston.

Claim 14

The invention as claimed in claim 9, in which said means to connect said poppet to said diaphragm and to said bellofram and piston is an elongated stem, and in which said resilient means is a helical compression spring mounted around said stem on the side of said bellofram chamber which is remote from said diaphragm chamber, said spring having its end adjacent said bellofram chamber seated on a fixed support, and its end remote from said bellofram chamber seated on a spring seat on said stem.

Claim 15

The invention as claimed in claim 9, in which said diaphragm chamber, said bellofram chamber and said valve seat are coaxial to each other, in which each of said diaphragm and said bellofram is disposed perpendicularly to and coaxial to the common axis of said chambers and valve seat, and in which said means to connect said poppet to said diaphragm and to said bellofram and piston is an elongated stem coaxial to said chambers and coaxial to said diaphragm and said bellofram.

Claim 16

The invention as claimed in claim 13, in which said wall means has the interior wall portion between said diaphragm chamber and said bellofram chamber, in which said stem is slidably mounted through an opening in said interior wall portion, and in which said means which causes the pressure in said first subchamber to be present in said third subchamber comprises port means extending through said interior wall portion between said first and third subchambers.

Claim 17

The invention as claimed in claim 9, in which means are provided to Vent said fourth subchamber to the ambient atmosphere, and in which the effective diameter of said valve seat is slightly larger than the diameter of said reverse-bent portion of said bellofram at a location midway between the outer wall of said piston and the wall of said bellofram chamber, whereby to maintain seating pressure of said poppet on said seat except during actual or incipient backflow conditions.

Claim 18

The invention as claimed in claim 15, in which the force exerted by said resilient means is only a few pounds.

Claim 19

The invention as claimed in claim 9, in which said seat has a substantially frustoconical upper surface which diverges upwardly and terminates in an apex edge having a diameter large in comparison to that of the remainder of the portion of said seat nearest said poppet, and in which said poppet has an elastomeric portion adapted to seat sealingly on said apex edge.

Claim 20

The invention as claimed in claim 17, in which said apex edge is defined by said frustoconical surface and also by a cylindrical surface, said cylindrical surface being coaxial with said seat.

Claim 21

The invention as claimed in claim 9, in which said poppet incorporates an elastomeric disc adapted to seat sealingly on said valve seat, in which a clamping ring is mounted coaxially against said disc on the side thereof remote from said diaphragm, said clamping ring having an upwardly divergent peripheral edge against which water impinges upon cracking of said poppet off said seat, said impingement of said water creating a reaction force tending to shift said poppet away from said seat.

Claim 22

The invention as claimed in claim 9, in which each of said check valves is a poppet valve which is spring biased toward closed position and is adapted to open in response to the presence of sufficient water pressure on the upstream side thereof.

Claim 23

The invention as claimed in claim 20, in which said poppet valves are mounted in a common housing, and in which each of said poppet valves includes a poppet which is movably mounted for movement in a direction oblique to the axis of said common housing.

Claim 24

The invention as claimed in claim 21, in which said wall means to define said diaphragm and bellofram chambers is removably secured to said common housing, in which the interior of said common housing communicates with said second subchamber through a large-area passage, and in which said means to transmit to said first subchamber the water pressure present in said water main comprises communicating internal passages which extend through said common housing and through said wall means.

Claim 25

The invention as claimed in claim 22, in which restrictor means are provided in at least one of said communicating internal passages.