Valves

Abstract

The invention relates to valves and particularly, though not exclusively, to gate valves. There is provided a valve comprising a housing ( 1 ) and a valve member ( 2 ) moveable within the housing ( 1 ) to open and close the valve. In a first aspect the valve is provided with means to reduce friction between the housing ( 1 ) and valve member ( 2 ). In a second aspect the valve is provided with an operating member ( 20 ) which is associated with the valve member ( 2 ) and passes through an aperture ( 21 ) in the housing ( 1 ) which is sealed when the valve is in the open position. Such a valve addresses difficulties relating to the operation of prior art valves, particularly gate valves, and specifically the difficulties created by frictional drag upon movement of the valve member, and difficulties in maintaining the valve.

1 - 22 . (canceled)  
   
   
       23 . A valve comprising a valve housing, a valve member slidable in the valve housing between open and closed positions, and means to reduce friction between the valve member and the valve housing.  
   
   
       24 . A valve according to  claim 23  wherein the valve comprises a gate valve and the slidable member comprises an obturator with low friction slide surfaces.  
   
   
       25 . A valve according to  claim 24  wherein the obturator is encapsulated in or made from elastomeric material to provide resistance to corrosion, the low friction sliding surfaces being provided externally of the elastomeric material.  
   
   
       26 . A valve according to  claim 24  wherein the low friction sliding surfaces are provided by at least one guide shoe made of low friction material, and attachable to the obturator.  
   
   
       27 . A valve according to  claim 26  wherein there are two guide shoes, provided at opposite edges of the obturator.  
   
   
       28 . A valve according to  claim 26  wherein the or each guide shoe is attachable to the obturator by inserting the shoes into a slot in the obturator.  
   
   
       29 . A valve according to  claim 28  wherein the or each guide shoe is arranged to cooperate with the slot in the obturator so that it cannot be extracted from the obturator in the direction of obturator motion.  
   
   
       30 . A valve according to  claim 28  wherein the or each guide shoe is provided with ridges arranged to contact the elastomeric material of the obturator to help retain the guide shoe in the associated slot.  
   
   
       31 . A valve according to  claim 30  wherein the ridges on the or each guide shoe are shaped to make it relatively easy to insert the guide shoe into the associated slot, but relatively hard for the shoe subsequently to move out of the slot again.  
   
   
       32 . A valve according to  claim 27  wherein the housing is provided with parallel guide ribs extending down each side of the housing, these ribs cooperating with parallel guide channels in the guide shoes, so that the obturator is guided by cooperation of the ribs and channels, as the obturator moves between the open and closed positions.  
   
   
       33 . A valve according to  claim 32  wherein the ribs on the valve housing comprise metal or metal provided with a corrosion protected coating.  
   
   
       34 . A valve according to  claim 32  wherein the inner surfaces of each guide shoe fit around the associated guide rib of the housing, with a sufficient clearance to allow sliding motion to take place.  
   
   
       35 . A valve according to  claim 28  wherein the back of the or each guide shoe may be shaped to fit into a recess within the associated guide slot of the obturator.  
   
   
       36 . A valve according to  claim 23  wherein the valve comprises a valve operating member associated with the valve member and passing out of the valve housing through an aperture, the valve having means to seal the aperture when the valve member is in the open position.  
   
   
       37 . A valve comprising: 
 a valve housing having an interior surface on an underside of the house;    a valve member slidable in the valve housing between open and closed positions:    a valve operating member associated with the valve member and passing out of the valve housing through an aperture;    seal means for sealing the aperture when the valve member is in the open position, and    low friction sliding surfaces provided by at least one guide shoe made of low friction material and attachable to the slidable valve member.