Dry pipe valve for fire protection sprinkler system

1. A fire protection system comprising:

a supply pipe having a first fluid pressurized to a first pressure;

a network of pipes having a plurality of sprinklers, the network of pipes having a second fluid being pressurized to a second pressure at approximately 5.5 times the first pressure; and

a dry pipe valve including:

a body defining a passage extending along a longitudinal axis between an inlet coupled to the supply pipe and an outlet coupled to the network of pipes, the inlet having an inlet diameter of approximately WD inches;

a seat disposed in the body, the seat having a seating surface with a diameter AD approximately less than two times WD inches; and

a clapper pivotable about an axis orthogonal to the longitudinal axis between a first position occluding the passage when the ratio of the second pressure to the first pressure is at least 5.5 and a second position permitting fluid flow through the passage when the ratio is less than 5.5, the seat disposed relative to the inlet such that the second pressure is sufficient to independently seal the clapper in the seat in the first position against the first pressure when the ratio of the second pressure to the first pressure is at least 5.5.

2. The system of claim 1 , wherein WD comprises a magnitude of about six inches.

3. The system of claim 1 , wherein the seating surface comprises first and second seating surfaces disposed on the body, the first seating surface disposed about the longitudinal axis, the second seating surface cincturing the first seating surface to define a seat axis offset to the longitudinal axis, the clapper having a first sealing surface disposed about the longitudinal axis and a second sealing surface cincturing the sealing surface to define a clapper axis offset to the longitudinal axis, the clapper cooperating with the seating surfaces in one position of the clapper to prevent fluid flow through the passage.

4. The system of claim 3 , wherein the clapper comprises a first distance between the pivot axis and the longitudinal axis, one of the clapper and seat axes being located at a second distance to the pivot axis of less than about 1.8 times the first distance.

5. A fire protection system comprising:

a supply pipe having a first fluid pressurized to a first pressure;

a network of pipes having a plurality of sprinklers, the network of pipes having a second fluid being pressurized to a second pressure at approximately 5.5 times the first pressure;

a housing defining a passage extending along a longitudinal axis between an inlet coupled to the supply pipe and an outlet coupled to a network of pipes, the inlet having an inlet diameter of approximately WD inches;

a seat body disposed in the housing, the seat body having a seating surface with a diameter AD approximately less than two times WD inches and including a first seating surface and a second seating surface cincturing the first seating surface, the first seating surface defining a first seat body axis and the second seating surface defining a second body axis offset to the first seat body axis, the first and second seating surfaces being generally disposed on a common plane, the first and second seating surfaces include metallic seating surfaces; and

a clapper being positioned to cooperate with the seat body and pivotable about an axis orthogonal to the longitudinal axis between a first position occluding the passage when a ratio of the second pressure to the first pressure is at least 5.5 and a second position permitting fluid flow through the passage when the ratio is less than 5.5, the clapper having first and second sealing surfaces, the first sealing surface defining a first axis, and the second sealing surface surrounding the first sealing surface to define a second axis offset to the first axis, the first and second sealing surfaces being respectively contiguous to the metallic first and second seating surfaces in one position of the clapper to prevent fluid flow through the seat body, the clapper having a solid surface extending between the first and second seating surfaces of the seat body.

6. The system of claim 5 , wherein at least one of the first and second sealing surface includes cantilevered lips extending oblique to one of the first and second axes.

7. The system of claim 5 , wherein the solid surface of the clapper and the seat body comprises a chamber.

8. The system of claim 7 , wherein the chamber comprises a recessed surface formed between the first and second seating surfaces.

9. The system of claim 7 , wherein the chamber comprises at least a recessed surface of the seat body that circumscribes the first seating surface of the seat body.

10. The system of claim 7 , wherein seat body comprises a drain port in communication with the chamber.

11. The system of claim 5 , wherein the first and second sealing surfaces are spaced apart from the first and second seating surfaces at another position of the clapper to permit fluid to flow through the seat body.