Butterfly valve

In a butterfly valve comprising a part in the form of a valve body and a part in the form of a butterfly valve member, means defining a fluid passageway extending throughout the body, the valve member being rotatable about an axis in said passageway between an extreme valve passageway closing position and an extreme valve passageway opening position, the passageway having an upstream inlet end for the inlet of the fluid and a downstream outlet end for the outlet of the fluid, one of said two parts having an annular cavity, an annular sealing element disposed in the cavity with an inner end of which cavity the sealing element defines an annular chamber, said one part and said sealing element constituting a unit and the other of said parts defining an annular surface for sealing contact with the sealing element in said extreme valve passageway closing position of the valve member, means for retaining the sealing element in the cavity, said unit defining a conduit which is capable of acting as an inlet and exists permanently irrespective of the position of the valve member and irrespective of the state of the sealing element and extends from the chamber to said passageway and is located longitudinally of said passageway on a side of the valve member adjacent said upstream inlet end of the passageway and is open to said passageway irrespective of the state of the sealing element when the valve member is in said extreme valve passageway closing position so as to enable the chamber to receive the fluid pressure which prevails on the side of the valve member adjacent said upstream inlet end of the passageway;

• the improvement comprising means defining a conduit in said unit and capable of acting as an outlet and permanently extending from said annular chamber to said passageway and positioned relative to said other part to be closed off from said passageway downstream outlet end by said other part when the valve member is in said extreme closing position and to be put by said other part in communication with said passageway downstream outlet end and thereby relieve the pressure in said chamber when and only when the valve member has been rotated away from said extreme closing position about said axis but before said annular surface has lost contact with said sealing element in a part of said valve member which is the most remote from said axis transversely of said passageway and located adjacent said downstream outlet end of the passageway in said extreme valve passageway opening position of the valve member, said conduit capable of acting as an outlet being located substantially at a point which is the most remote from the axis of rotation of the valve member transversely of said passageway and is located on the side of an immediately adjacent portion of the valve member which is adjacent said outlet end of said passageway when the valve member is in the vicinity of said extreme valve passageway closing position and slightly opens said passageway.

In a butterfly valve comprising a part in the form of a valve body and a part in the form of a butterfly valve member, means defining a fluid passageway extending throughout the body, the valve member being rotatable about an axis in said passageway between an extreme valve passageway closing position and an extreme valve passageway opening position, the passageway having an upstream inlet end for the inlet of the fluid and a downstream outlet end for the outlet of the fluid, one of said two parts having an annular cavity, an annular sealing element disposed in the cavity with an inner end of which cavity the sealing element defines an annular chamber and the other of said parts defining an annular surface for sealing contact with the sealing element in said extreme valve passageway closing position of the valve member, means for retaining the sealing element in the cavity, means defining a conduit which exists permanently irrespective of the position of the valve member and irrespective of the effect of fluid pressure on the sealing element and extends from the chamber to said passageway and is located longitudinally of said passageway on a side of the valve member adjacent said upstream inlet end of the passageway and is open to said passageway irrespective of the effect of fluid pressure on the sealing element when the valve member is in said extreme valve passageway closing position so as to enable the chamber to receive the fluid pressure which prevails on the side of the valve member adjacent said upstream inlet end of the passageway;

• the improvement comprising locating said pg,27 conduit in said sealing element in a position to be put by said other part in communication with said passageway downstream outlet end and thereby relieve the pressure in said chamber when and only when the valve member has been rotated away from said extreme closing position about said axis but before said annular surface has lost contact with said sealing element in a part of said valve member which is the most remote from said axis transversely of the passageway and located adjacent said downstream outlet end of the passageway in said extreme valve passageway opening position of the valve member, said conduit being located in a region of the periphery of said sealing element which is the most remote from said axis transversely of said passageway, said region being situated on a side of said valve member which is adjacent said downstream outlet end of the passageway when the valve member is in the vicinity of said extreme valve passageway closing position and slightly opens said passageway.

In a butterfly valve comprising a part in the form of a valve body and a part in the form of a butterfly valve member, means defining a fluid passageway extending throughout the body, the valve member being rotatable about an axis in said passageway between an extreme valve passageway closing position and an extreme valve passageway opening position, the passageway having an upstream inlet end for the inlet of the fluid and a downstream outlet end for the outlet of the fluid, one of said two parts having an annular cavity, an annular sealing element disposed in the cavity with an inner end of which cavity the sealing element defines an annular chamber, said one part and said sealing element constituting a unit and the other of said parts defining an annular surface for sealing contact with the sealing element in said extreme valve passageway closing position of the valve member, means for retaining the sealing element in the cavity, said unit defining a conduit which is capable of acting as an inlet and exists permanently irrespective of the position of the valve member and irrespective of the state of the sealing element and extends from the chamber to said passageway and is located longitudinally of said passageway on a side of the valve member adjacent said upstream inlet end of the passageway and is open to said passageway irrespective of the state of the sealing element when the valve member is in said extreme valve passageway closing position so as to enable the chamber to receive the fluid pressure which prevails on the side of the valve member adjacent said upstream inlet end of the passageway;

• the improved comprising means defining a conduit in said unit and capable of acting as an outlet and permanently extending from said annular chamber to said passageway and positioned relative to said other part to be closed off from said passageway downstream outlet end by said other part when the valve member is in said extreme closing position and to be put by said other part in communication with said passageway downstream outlet end and thereby relieve the pressure in said chamber when and only when the valve member has been rotated away from said extreme closing position about said axis but before said annular surface has lost contact with said sealing element in a part of said valve member which is the most remote from said axis transversely of said passageway and located adjacent said downstream outlet end of the passageway in said extreme valve passageway opening position of the valve member, said cavity being formed in the valve body and said conduit capable of acting as an inlet being formed in said body, the conduit capable of acting as an outlet extending through the sealing element and being so disposed as to be closed by said surface of contact when the valve member is in said extreme valve passageway closing position, said conduit capable of acting as an outlet being in a region of said unit which is the most remote from the axis of rotation of the valve member transversely of said passageway and is located on the side of an immediately adjacent portion of the valve member shich is adjacent said outlet end of said passageway when the valve member is in the vicinity of said extreme valve passageway closing position and slightly opens said passageway.

In a butterfly valve comprising a part in the form of a valve body and a part in the form of a butterfly valve member, means defining a fluid passageway extending throughout the body, the valve member being rotatable about an axis in said passageway between an extreme valve passageway closing position and an extreme valve passageway opening position, the passageway having an upstream inlet end for the inlet of the fluid and a downstream outlet end for the outlet of the fluid, one of said two parts having an annular cavity, an anular sealing element disposed in the cavity with an inner end of which cavity the sealing element defines an annular chamber, said one part and said sealing element constituting a unit and the other of said parts defining an annular surface for sealing contact with the sealing element in said extreme valve passageway closing position of the valve member, means for retaining the sealing element in the cavity, said unit defining a conduit which is capable of acting as an inlet and exists permanently irrespective of the position of the valve member and irrespective of the state of the sealing element and extends from the chamber to said passageway and is located longitudinally of said passageway on a side of the valve member adjacent said upstream inlet end of the passageway and is open to said passageway irrespective of the state of the sealing element when the valve member is in said extreme valve passageway closing position so as to enable the chamber to receive the fluid pressure which prevails on the side of the valve member adjacent said upstream inlet end of the passageway;

• the improvement comprising means defining a conduit in said unit and capable of acting as an outlet and permanently extending from said annular chamber to said passageway and positioned relative to said other part to be closed off from said passageway downstream outlet end by said other part when the valve member is in said extreme closing position and to be put by said other part in communication with said passageway downstream outlet end and thereby relieve the pressure in said chamber when and only when the valve member has been rotated away from said extreme closing position about said axis but before said annular surface has lost contact with said sealing element in a part of said valve member which is the most remote from said axis transversely of said passageway and located adjacent said downstream outlet end of the passageway in said extreme valve passageway opening position of the valve member, said cavity being formed in the valve member and the conduit capable of acting as an inlet being formed in the valve member and the conduit capable of acting as an outlet being disposed in such manner as to be closed when the valve member is in said extreme valve passageway closing position and said conduit capable of acting as an outlet being located in a region of said valve member which is the most remote from said axis of rotation and is the nearest to said downstream outlet end when said valve member is in said extreme opening position.