Fire hydrant check valve

Abstract

A check valve for a fire hydrant system is configured to allow fluid to flow in a direction from a pressurized water supply to a fire hydrant and to restrict fluid from flowing from the fire hydrant to the pressurized water supply. The check valve includes an internal cavity and a flapper capable of moving between an open position wherein the flapper is positioned against a side of the internal cavity so as to substantially not impede flow of fluid therethrough and a closed position wherein the flapper creates a seal to restrict flow of fluid therethrough.

1 . A check valve for restricting backflow of fluid in a fire hydrant system, comprising:
 a body defining an internal cavity having a generally hollow and generally cylindrical shape with an inlet end and an outlet end wherein the inlet end and the outlet end have respective openings;   a seat ring disposed on the inlet end;   a flapper configured when in a closed position to create a seal with the seat ring and inlet end to restrict the flow of fluid from the outlet end to the inlet end;   wherein the flapper and the body are configured such that the flapper pivots against a side of the internal cavity in an open position during fluid flow from the inlet end to the outlet end leaving an internal cavity opening of the internal cavity and the flapper at least approximately as wide as the respective openings of the inlet end and the outlet end.   
   
   
       2 . The check valve of  claim 1  wherein the flapper and body are configured so that the flapper in the open position pivots against a top side of the internal cavity such that gravity force biases the flapper toward the closed position. 
   
   
       3 . The check valve of  claim 1  further comprising sealing elements positioned between a rear surface of the seat ring and the flapper in the closed position and a front surface of the seat ring and the check valve body to create water-tight seals therebetween. 
   
   
       4 . The check valve of  claim 3  wherein the sealing element comprises O-rings disposed in channels defined by a rear surface of the seat ring and an inlet inner surface of the check valve body configured to create a water-tight seal between the rear surface of the seat ring and the flapper in the closed position and the front surface of the seat ring and the inlet inner surface of the check valve body. 
   
   
       5 . The check valve of  claim 1  further comprising a torsion spring disposed in the body to provide a spring force against the flapper to hasten movement of the flapper toward the closed position to restrict a water hammer effect. 
   
   
       6 . The check valve of  claim 5  wherein the torsion spring biases the flapper to the closed position. 
   
   
       7 . The check valve of  claim 1  wherein the respective openings of the inlet end and the outlet end have approximately equal diameters and the internal cavity opening of the internal cavity and the flapper when in the open position has an internal diameter at least as wide as the respective openings of the inlet end and the outlet end. 
   
   
       8 . The check valve of  claim 1  further comprising a swiveling mechanical joint flange disposed on at least one of the inlet end and the outlet end to rigidly couple the check valve to a pipe extending therefrom. 
   
   
       9 . The check valve of  claim 8 , wherein the swiveling mechanical joint flange is integral with the body. 
   
   
       10 . A fire hydrant system for restricting the backflow of water, the fire hydrant system comprising:
 a barrel extending generally vertically upward above ground level;   a pipe in communication with the barrel and extending generally vertically downward therefrom below ground level;   an elbow in communication with the pipe and extending generally horizontally therefrom;   an underground water pipe in communication with a pressurized water supply configured to facilitate flow of water from the pressurized water supply to the barrel;   a check valve separate from and in communication with the elbow on a first side and in communication with the underground water pipe on a second side to allow flow of water from the underground water pipe to the barrel and to restrict the flow of water from the barrel to the underground water pipe;   a flapper disposed in the check valve and configured to come in contact with a seat ring thereby creating a seal to restrict the flow of water from the barrel to the underground water pipe;   the flapper and check valve further configured to substantially not impede fluid flow from the underground water pipe to the barrel.   
   
   
       11 . The fire hydrant system of  claim 10  wherein the flapper is rotatably attached to a pivot point in the check valve such that the flapper can move between an open position wherein the flapper is positioned against an inner portion of the check valve and a closed position wherein a sealing face of the flapper is in contact with the seat ring for creating a seal between the flapper and the seat ring to restrict the flow of water from the barrel to the underground water pipe. 
   
   
       12 . The fire hydrant system of  claim 11  further comprising sealing elements positioned between a rear surface of the seat ring and the flapper in the closed position and a front surface of the seat ring and the check valve body to create water-tight seals therebetween. 
   
   
       13 . The check valve of  claim 12  wherein the sealing elements comprise O-rings disposed in channels defined by a rear surface of the seat ring and an inlet inner surface of the check valve body configured to create a water-tight seal between the rear surface of the seat ring and the flapper in the closed position and the front surface of the seat ring and the inlet inner surface of the check valve body. 
   
   
       14 . The fire hydrant system of  claim 10  wherein the check valve and the flapper are configured such that when the flapper is in the open position it is positioned against a top portion of the check valve closer to the ground surface so that gravity biases the flapper away from the open position and toward the closed position. 
   
   
       15 . The fire hydrant system of  claim 10  further comprising:
 a torsion spring to provide a spring force against the flapper to hasten movement of the flapper and restrict a water hammer effect of the flapper.   
   
   
       16 . The fire hydrant system of  claim 15  wherein the torsion spring biases the flapper to the closed position. 
   
   
       17 . The fire hydrant system of  claim 10  further comprising a swiveling mechanical joint flange disposed on at least one end of the check valve for rigidly coupling the check valve to the underground water pipe or the elbow. 
   
   
       18 . The check valve of  claim 17 , wherein the swiveling mechanical joint flange is integral with the check valve. 
   
   
       19 . A check valve for restricting backflow of water in a fire hydrant system comprising:
 a body defining a hollow internal cavity and having an inlet and an outlet, wherein water can enter from a pressurized system at the inlet and exit from the outlet;   a seat ring;   a flapper of generally disk shape pivotably connected in the hollow internal cavity such that the flapper can move between an open position wherein the flapper is positioned against an inner portion of the hollow internal cavity and a closed position wherein a sealing face of the flapper is in contact with the seat ring for creating a seal between the flapper and the seat ring to restrict flow of water from the outlet to the inlet;   a torsion spring attached to the pivot point with an extension for contacting an outer surface of the flapper to bias the flapper to the closed position.   
   
   
       20 . The check valve of  claim 19  further comprising sealing elements positioned between a rear surface of the seat ring and the flapper in the closed position and the front surface of the seat ring and the check valve body to create water-tight seals therebetween. 
   
   
       21 . The check valve of  claim 20  wherein the sealing elements comprise O-rings disposed in channels defined by a rear surface of the seat ring and an inlet inner surface of the check valve body configured to create a water-tight seal between the rear surface of the seat ring and the flapper in the closed position and the front surface of the seat ring and the inlet inner surface of the check valve body. 
   
   
       22 . The check valve of  claim 19  further comprising a swiveling mechanical joint flange disposed on at least one of the inlet and the outlet for rigidly coupling the check valve to pipes extending therefrom. 
   
   
       23 . The check valve of  claim 22 , wherein the swiveling mechanical joint flange is made integral with the body. 
   
   
       24 . The check valve of  claim 19  wherein the inner portion is shaped to receive the flapper when in the open position such that an internal cavity opening for the body with the flapper in the open position is at least as large as an inlet opening and an outlet opening. 
   
   
       25 . The check valve of  claim 24  wherein the inlet opening and the outlet opening have approximately equal diameters.