Ball valve

The present invention is a ball valve which may be attached to a fluid pipe for connection/disconnection between an entrance and an exit. More particularly, the present invention is a ball valve having a discharge orifice communicating with ambient air in addition to the entrance and the exit for connection/disconnection between the entrance and the discharge orifice and/or between the exit and the discharge orifice. The ball valve of the present invention may be attached to piping systems such as, for example, the secondary side of a steam trap, which blocks steam but automatically discharges condensed water, and is used for checking a discharging state of the primary side steam trap and/or releasing remaining pressure on the secondary side.

CROSS REFERENCE TO RELATED APPLICATIONS

The present invention claims priority to application Nos. 2003-169317, 2003-169318, and 2003-169319 filed in Japan on Jun. 13, 2003, and Application Nos. 2003-416269, 2003-416270, and 2003-416271 filed in Japan on Dec. 15, 2003 which are expressly incorporated herein in their entirety by reference thereto.

FIELD OF INVENTION

The present invention is an improved ball valve which, when placed in a piping system, is capable of discharging fluid outside of the piping system from upstream and/or downstream of the ball valve. A discharge orifice in the ball valve of the present invention communicates with ambient air and can be used to discharge liquid from the entrance or exit of the ball valve while the ball valve is closed and/or may be used to release remaining pressure at the ball valve's exit.

BACKGROUND OF THE INVENTION

A conventional ball valve is disclosed in, e.g., Japanese Published Unexamined Utility-Model Application No. Sho 59-188360. In the conventional ball valve, a valve chamber with entrance and exit communicating with each other in a casing is formed, a valve ball with a circulation hole is provided in the valve chamber, and an entrance-side ring valve seat is provided on the entrance side of the valve ball while an exit-side ring valve seat is provided on the exit side of the valve ball. The entrance and exit are connected or disconnected by rotating the valve ball with a valve shaft hermetically passing through the casing.

In the above-described conventional ball valve, the entrance and exit are connected/disconnected by rotate-operating the valve ball. However, the conventional ball valve lacks the capability of discharging fluid at its entrance from a discharge orifice communicating ambient air different from the entrance and exit, and/or releasing remaining pressure at its exit. For this reason, it is impossible to check the discharging state of a steam trap provided on the primary side and/or to release remaining pressure on the secondary side.

Accordingly, the purpose of the present invention is to provide a ball valve which enables the discharge of fluid in its entrance from a discharge orifice communicating ambient air different from the entrance and exit, and/or the release of remaining pressure in the exit side of the ball valve.

SUMMARY OF THE INVENTION

The present invention is a ball valve in which a valve chamber with an entrance and exit communicating with each other in a casing is formed, a valve ball with a circulation hole is provided in the valve chamber, an entrance-side ring valve seat is provided on the entrance side and an exit-side ring valve seat is provided on the exit side of the valve ball, the entrance and the exit are connected or disconnected by rotate-operating the valve ball with a valve shaft hermetically passing through the casing, wherein a through hole passing through from a valve ball contact surface to a casing contact surface is formed in the exit-side ring valve seat, and a discharge orifice with one end communicating the through hole of the exit-side ring valve seat and the other end communicating ambient air is formed, and wherein a first passage hole which connects the circulation hole with the entrance in a first disconnection state where the valve ball disconnects the entrance from the exit, and which connects the circulation hole with the exit in a second disconnection state where the valve ball is rotated by 180 degrees from the first disconnection state so as to disconnect the entrance from the exit, and a second passage hole which connects the circulation hole with the through hole in the first disconnection state and which is disconnected from the through hole in the exit-side ring valve seat in the second disconnection state, are formed in the valve ball.

The present invention is also a ball valve in which a valve chamber with an entrance and exit communicating with each other in a casing is formed, a valve ball with a circulation hole is provided in the valve chamber, an entrance-side ring valve seat is provided on the entrance side and an exit-side ring valve seat is provided on the exit side of the valve ball, the entrance and the exit are connected or disconnected by rotate-operating the valve ball with a valve shaft hermetically passing through the casing, wherein a through hole passing through from a valve ball contact surface to a casing contact surface is formed in the entrance-side ring valve seat, and a discharge orifice with one end communicating the through hole of the entrance-side ring valve seat and the other end communicating ambient air is formed, and wherein a first passage hole which connects the circulation hole with the entrance in a first disconnection state where the valve ball disconnects the entrance from the exit, and which connects the circulation hole with the exit in a second disconnection state where the valve ball is rotated by 180 degrees from the first disconnection state so as to disconnect the entrance from the exit, and a second passage hole which connects the circulation hole with the through hole in the first disconnection state and which is disconnected from the through hole in the entrance-side ring valve seat in the second disconnection state, are formed in the valve ball.

In the ball valve according to these example embodiments of the invention, in the first disconnection state where the valve ball is rotate-operated to disconnect the entrance from the exit, the entrance and the discharge orifice communicate with each other through the first passage hole, the circulation hole, the second passage hole and the through hole. In the second disconnection state where the valve ball is rotate-operated by 180 degrees from the first disconnection state, the entrance, the exit and the discharge orifice are disconnected. In these arrangements, fluid at the entrance can be discharged from the discharge orifice communicating ambient air different from the entrance and exit.

The present invention is also a ball valve in which a valve chamber with an entrance and exit communicating with each other in a casing is formed, a valve ball with a circulation hole is provided in the valve chamber, an entrance-side ring valve seat is provided on the entrance side and an exit-side ring valve seat is provided on the exit side of the valve ball, the entrance and the exit are connected or disconnected by rotate-operating the valve ball with a valve shaft hermetically passing through the casing, wherein a through hole passing through from a valve ball contact surface to a casing contact surface is formed in the exit-side ring valve seat, and a discharge orifice with one end communicating the through hole of the exit-side ring valve seat and the other end communicating ambient air is formed, and wherein a first passage hole which connects the circulation hole with the entrance in a first disconnection state where the valve ball disconnects the entrance from the exit, and which connects the circulation hole with the exit in a second disconnection state where the valve ball is rotated by 180 degrees from the first disconnection state so as to disconnect the entrance from the exit, and a third passage hole which connects the circulation hole with the through hole in the second disconnection state and which is disconnected from the through hole in the exit-side ring valve seat in the first disconnection state, are formed in the valve ball.

The present invention is also a ball valve in which a valve chamber with an entrance and exit communicating with each other in a casing is formed, a valve ball with a circulation hole is provided in the valve chamber, an entrance-side ring valve seat is provided on the entrance side and an exit-side ring valve seat is provided on the exit side of the valve ball, the entrance and the exit are connected or disconnected by rotate-operating the valve ball with a valve shaft hermetically passing through the casing, wherein a through hole passing through from a valve ball contact surface to a casing contact surface is formed in the entrance-side ring valve seat, and a discharge orifice with one end communicating the through hole of the entrance-side ring valve seat and the other end communicating ambient air is formed, and wherein a first passage hole which connects the circulation hole with the entrance in a first disconnection state where the valve ball disconnects the entrance from the exit, and which connects the circulation hole with the exit in a second disconnection state where the valve ball is rotated by 180 degrees from the first disconnection state so as to disconnect the entrance from the exit, and a third passage hole which connects the circulation hole with the through hole in the second disconnection state and which is disconnected from the through hole in the entrance-side ring valve seat in the first disconnection state, are formed in the valve ball.

In the ball valve according to these example embodiments of the present invention, in the first disconnection state where the valve ball is rotate-operated to disconnect the entrance from the exit, the entrance, the exit and the discharge orifice are disconnected. In the second disconnection state where the valve ball is rotate-operated by 180 degrees from the first disconnection state, the exit and the discharge orifice communicate with each other through the first passage hole, the circulation hole, the third passage hole and the through hole. In these arrangements, remaining pressure at the exit can be released from the discharge orifice communicating ambient air different from the entrance and exit.

The present invention is also a ball valve in which a valve chamber with an entrance and exit communicating with each other in a casing is formed, a valve ball with a circulation hole is provided in the valve chamber, an entrance-side ring valve seat is provided on the entrance side and an exit-side ring valve seat is provided on the exit side of the valve ball, the entrance and the exit are connected or disconnected by rotate-operating the valve ball with a valve shaft hermetically passing through the casing, wherein a through hole passing through from a valve ball contact surface to a casing contact surface is formed in the exit-side ring valve seat, and a discharge orifice with one end communicating the through hole of the exit-side ring valve seat and the other end communicating ambient air is formed, and wherein a first passage hole which connects the circulation hole with the entrance in a first disconnection state where the valve ball disconnects the entrance from the exit, and which connects the circulation hole with the exit in a second disconnection state where the valve ball is rotated by 180 degrees from the first disconnection state so as to disconnect the entrance from the exit, a second passage hole which connects the circulation hole with the through hole in the first disconnection state and which is disconnected from the through hole in the exit-side ring valve seat in the second disconnection state, and a third passage hole which connects the circulation hole with the through hole in the second disconnection state and which is disconnected from the through hole in the exit-side ring valve seat in the first disconnection state, are formed in the valve ball.

The present invention is also a ball valve in which a valve chamber with an entrance and exit communicating with each other in a casing is formed, a valve ball with a circulation hole is provided in the valve chamber, an entrance-side ring valve seat is provided on the entrance side and an exit-side ring valve seat is provided on the exit side of the valve ball, the entrance and the exit are connected or disconnected by rotate-operating the valve ball with a valve shaft hermetically passing through the casing, wherein a through hole passing through from a valve ball contact surface to a casing contact surface is formed in the entrance-side ring valve seat, and a discharge orifice with one end communicating the through hole of the entrance-side ring valve seat and the other end communicating ambient air is formed, and wherein a first passage hole which connects the circulation hole with the entrance in a first disconnection state where the valve ball disconnects the entrance from the exit, and which connects the circulation hole with the exit in a second disconnection state where the valve ball is rotated by 180 degrees from the first disconnection state so as to disconnect the entrance from the exit, a second passage hole which connects the circulation hole with the through hole in the first disconnection state and which is disconnected from the through hole in the entrance-side ring valve seat in the second disconnection state, and a third passage hole which connects the circulation hole with the through hole in the second disconnection state and which is disconnected from the through hole in the entrance-side ring valve seat in the first disconnection state, are formed in the valve ball.

In the ball valve according to these example embodiments of the present invention, in the first disconnection state where the valve ball is rotate-operated to disconnect the entrance from the exit, the entrance and the discharge orifice communicate with each other through the first passage hole, the circulation hole, the second passage hole and the through hole. In the second disconnection state where the valve ball is rotate-operated by 180 degrees from the first disconnection state, the exit and the discharge orifice communicate with each other through the first passage hole, the circulation hole, the third passage hole and the through hole. In these arrangements, fluid at the entrance can be discharged from the discharge orifice communicating ambient air different from the entrance and exit, and remaining pressure at the exit can be released from the discharge orifice.

DETAILED DESCRIPTION

An example embodiment of the invention is shown inFIGS. 1 to 4. A casing is formed by fastening an entrance side member3having an entrance2and an exit side member5having an exit4to a main body1with bolts6and nuts7, and a valve chamber8where the entrance2and the exit4communicate with each other is formed in the casing.

A valve ball10where a circulation hole9is formed in a straight line in a horizontal direction is rotatably provided in the valve chamber8. An entrance-side ring valve seat11is provided on the entrance2side of the valve ball10, and an exit-side ring valve seat12is provided on the exit4side of the valve ball10. The valve ball10has a parallel key groove13in its upper part, and a key member at a lower end of a valve shaft14passing through the main body1is engaged with the key groove. The valve shaft14holds airtightness with the main body1with a packing15and is fixed to the main body1with nuts16. Reference numerals17,18,19and20denote washers; and21, a packing holder. A handle22for rotation operation is fixed to the valve shaft14with nuts23.

The exit-side ring valve seat12has a through hole24passing through from a contact surface of the valve ball10to a contact surface of the exit side member5. The exit side member5has a discharge orifice25with one end communicating the through hole24of the exit-side ring valve seat12and the other end communicating ambient air. The through hole24is provided in a lower part of the exit-side ring valve seat12in parallel to a center line of the entrance2and the exit4. The valve ball10has a first passage hole26which connects the circulation hole9with the entrance2in a first disconnection state where the valve ball10disconnects the entrance2from the exit4, and which connects the circulation hole9with the exit4in a second disconnection state where the valve ball10is rotated by 180 degrees from the first disconnection state to disconnect the entrance2from the exit4, and a second passage hole27which connects the circulation hole9with the through hole24in the first disconnection state and which is disconnected by the entrance-side ring valve seat11in the second disconnection state. The first passage hole26is provided in the horizontal direction at a right angle to the circulation hole9, and its central axis passes through the center of the valve ball10. The second passage hole27is provided downwardly by 45 degrees from the horizontal direction, and its central axis passes through the center of the valve ball10.

FIGS. 1 and 2show a state where the entrance2and the exit4communicate with each other through the circulation hole9of the valve ball10. When the valve shaft14is rotated by 90 degrees from this state in a counterclockwise direction with the handle22, to set the first disconnection state as shown inFIG. 3where the valve ball10disconnects the entrance2from the exit4, the entrance2and the discharge orifice25communicate with each other through the first passage hole26, the circulation hole9, the second passage hole27and the through hole24, and fluid at the entrance2can be discharged from the discharge orifice25communicating ambient air different from the entrance2and the exit4. When the valve shaft14is rotated by 180 degrees with the handle22from the first disconnection state, to set the second disconnection state as shown inFIG. 4, the entrance2, the exit4and the discharge orifice25are disconnected.

Another example embodiment of the invention is shown inFIGS. 5 to 8. A casing is formed by fastening an entrance side member3having an entrance2and an exit side member5having an exit4to a main body1with bolts6and nuts7, and a valve chamber8where the entrance2and the exit4communicate with each other is formed in the casing.

A valve ball10where a circulation hole9is formed in a straight line in a horizontal direction is rotatably provided in the valve chamber8. An entrance-side ring valve seat11is provided on the entrance2side of the valve ball10, and an exit-side ring valve seat12is provided on the exit4side of the valve ball10. The valve ball10has a parallel key groove13in its upper part, and a key member at a lower end of a valve shaft14passing through the main body1is engaged with the key groove. The valve shaft14holds airtightness with the main body1with a packing15and is fixed to the main body1with nuts16. Reference numerals17,18,19and20denote washers; and21, a packing holder. A handle22for rotation operation is fixed to the valve shaft14with nuts23.

The exit-side ring valve seat12has a through hole24passing through from a contact surface of the valve ball10to a contact surface of the exit side member5. The exit side member5has a discharge orifice25with one end communicating the through hole24of the exit-side ring valve seat12and the other end communicating ambient air. The through hole24is provided in a lower part of the exit-side ring valve seat12in parallel to a center line of the entrance2and the exit4. The valve ball10has a first passage hole26which connects the circulation hole9with the entrance2in a first disconnection state where the valve ball10disconnects the entrance2from the exit4, and which connects the circulation hole9with the exit4in a second disconnection state where the valve ball10is rotated by 180 degrees from the first disconnection state to disconnect the entrance2from the exit4, and a third passage hole28which connects the circulation hole9with the through hole24in the second disconnection state and which is disconnected by the entrance-side ring valve seat11in the first disconnection state. The first passage hole26is provided in the horizontal direction at a right angle to the circulation hole9, and its central axis passes through the center of the valve ball10. The third passage hole28is provided downwardly by 45 degrees from the horizontal direction, and its central axis passes through the center of the valve ball10.

FIGS. 5 and 6show a state where the entrance2and the exit4communicate with each other through the circulation hole9of the valve ball10. When the valve shaft14is rotated by 90 degrees from this state in a counterclockwise direction with the handle22, to set the first disconnection state as shown inFIG. 7where the valve ball10disconnects the entrance2from the exit4, the entrance2, the exit4and the discharge orifice25are disconnected. When the valve shaft14is rotated by 180 degrees with the handle22from the first disconnection state, to set the second disconnection state as shown inFIG. 8, the exit4and the discharge orifice25communicate with each other through the first passage hole26, the circulation hole9, the third passage hole28and the through hole24, and remaining pressure at the exit4can be released from the discharge orifice25.

Another example embodiment of the invention is shown inFIGS. 9 to 12. A casing is formed by fastening an entrance side member3having an entrance2and an exit side member5having an exit4to a main body1with bolts6and nuts7, and a valve chamber8where the entrance2and the exit4communicate with each other is formed in the casing.

A valve ball10where a circulation hole9is formed in a straight line in a horizontal direction is rotatably provided in the valve chamber8. An entrance-side ring valve seat11is provided on the entrance2side of the valve ball10, and an exit-side ring valve seat12is provided on the exit4side of the valve ball10. The valve ball10has a parallel key groove13in its upper part, and a key member at a lower end of a valve shaft14passing through the main body1is engaged with the key groove. The valve shaft14holds airtightness with the main body1with a packing15and is fixed to the main body1with nuts16. Reference numerals17,18,19and20denote washers; and21, a packing holder. A handle22for rotation operation is fixed to the valve shaft14with nuts23.

The exit-side ring valve seat12has a through hole24passing through from a contact surface of the valve ball10to a contact surface of the exit side member5. The exit side member5has a discharge orifice25with one end communicating the through hole24of the exit-side ring valve seat12and the other end communicating ambient air. The through hole24is provided in a lower part of the exit-side ring valve seat12in parallel to a center line of the entrance2and the exit4. The valve ball10has a first passage hole26which connects the circulation hole9with the entrance2in a first disconnection state where the valve ball10disconnects the entrance2from the exit4, and which connects the circulation hole9with the exit4in a second disconnection state where the valve ball10is rotated by 180 degrees from the first disconnection state to disconnect the entrance2from the exit4, a second passage hole27which connects the circulation hole9with the through hole24in the first disconnection state and which is disconnected by the entrance-side ring valve seat11in the second disconnection state, and a third passage hole28which connects the circulation hole9with the through hole24in the second disconnection state and which is disconnected by the entrance-side ring valve seat11in the first disconnection state. The first passage hole26is provided in the horizontal direction at a right angle to the circulation hole9, and its central axis passes through the center of the valve ball10. The second passage hole27and the third passage hole28are respectively provided downwardly by 45 degrees from the horizontal direction, and their respective central axes pass through the center of the valve ball10.

FIGS. 9 and 10show a state where the entrance2and the exit4communicate with each other through the circulation hole9of the valve ball10. When the valve shaft14is rotated by 90 degrees from this state in a counterclockwise direction with the handle22, to set the first disconnection state as shown inFIG. 11where the valve ball10disconnects the entrance2from the exit4, the entrance2and the discharge orifice25communicate with each other through the first passage hole26, the circulation hole9, the second passage hole27and the through hole24, and fluid at the entrance2can be discharged from the discharge orifice25communicating ambient air different from the entrance2and the exit4. When the valve shaft14is rotated by 180 degrees with the handle22from the first disconnection state, to set the second disconnection state as shown inFIG. 12, the exit4and the discharge orifice25communicate with each other through the first passage hole26, the circulation hole9, the third passage hole28and the through hole24, and remaining pressure at the exit4can be released from the discharge orifice25.

Another example embodiment of the invention is shown inFIGS. 13 to 16. A casing is formed by fastening an entrance side member53having an entrance52and an exit side member55having an exit54to a main body51with bolts56and nuts57, and a valve chamber58where the entrance52and the exit54communicate with each other is formed in the casing.

A valve ball60where a circulation hole59is formed in a straight line in a horizontal direction is rotatably provided in the valve chamber58. An entrance-side ring valve seat61is provided on the entrance52side of the valve ball60, and an exit-side ring valve seat62is provided on the exit54side of the valve ball60. The valve ball60has a parallel key groove63in its upper part, and a key member at a lower end of a valve shaft54passing through the main body51is engaged with the key groove. The valve shaft64holds airtightness with the main body51with a packing65and is fixed to the main body51with nuts66. Reference numerals67,68,69and70denote washers; and71, a packing holder. A handle72for rotation operation is fixed to the valve shaft64with nuts73.

The entrance-side ring valve seat61has a through hole74passing through from a contact surface of the valve ball60to a contact surface of the entrance side member53. The entrance side member53has a discharge orifice75with one end communicating the through hole74of the entrance-side ring valve seat61and the other end communicating ambient air. The through hole74is provided in a lower part of the entrance-side ring valve seat61in parallel to a center line of the entrance52and the exit54. The valve ball60has a first passage hole76which connects the circulation hole59with the entrance52in a first disconnection state where the valve ball60disconnects the entrance52from the exit54, and which connects the circulation hole59with the exit54in a second disconnection state where the valve ball60is rotated by 180 degrees from the first disconnection state to disconnect the entrance52from the exit54, and a second passage hole77which connects the circulation hole59with the through hole74in the first disconnection state and which is disconnected by the exit-side ring valve seat62in the second disconnection state. The first passage hole76is provided in the horizontal direction at a right angle to the circulation hole59, and its central axis passes through the center of the valve ball60. The second passage hole77is provided downwardly by 45 degrees from the horizontal direction, and its central axis passes through the center of the valve ball60.

FIGS. 13 and 14show a state where the entrance52and the exit54communicate with each other through the circulation hole59of the valve ball60. When the valve shaft64is rotated by 90 degrees from this state in a counterclockwise direction with the handle72, to set the first disconnection state as shown inFIG. 15where the valve ball60disconnects the entrance52from the exit54, the entrance52and the discharge orifice75communicate with each other through the first passage hole76, the circulation hole59, the second passage hole77and the through hole74, and fluid at the entrance52can be discharged from the discharge orifice75communicating ambient air different from the entrance52and the exit54. When the valve shaft64is rotated by 180 degrees with the handle72from the first disconnection state, to set the second disconnection state as shown inFIG. 16, the entrance52, the exit54and the discharge orifice75are disconnected.

Another example embodiment of the invention is shown inFIGS. 17 to 20. A casing is formed by fastening an entrance side member53having an entrance52and an exit side member55having an exit54to a main body51with bolts56and nuts57, and a valve chamber58where the entrance52and the exit54communicate with each other is formed in the casing.

A valve ball60where a circulation hole59is formed in a straight line in a horizontal direction is rotatably provided in the valve chamber58. An entrance-side ring valve seat61is provided on the entrance52side of the valve ball60, and an exit-side ring valve seat62is provided on the exit54side of the valve ball60. The valve ball60has a parallel key groove63in its upper part, and a key member at a lower end of a valve shaft54passing through the main body51is engaged with the key groove. The valve shaft64holds airtightness with the main body51with a packing65and is fixed to the main body51with nuts66. Reference numerals67,68,69and70denote washers; and71, a packing holder. A handle72for rotation operation is fixed to the valve shaft64with nuts73.

The entrance-side ring valve seat61has a through hole74passing through from a contact surface of the valve ball60to a contact surface of the entrance side member53. The entrance side member53has a discharge orifice75with one end communicating the through hole74of the entrance-side ring valve seat61and the other end communicating ambient air. The through hole74is provided in a lower part of the entrance-side ring valve seat61in parallel to a center line of the entrance52and the exit54. The valve ball60has a first passage hole76which connects the circulation hole59with the entrance52in a first disconnection state where the valve ball60disconnects the entrance52from the exit54, and which connects the circulation hole59with the exit54in a second disconnection state where the valve ball60is rotated by 180 degrees from the first disconnection state to disconnect the entrance52from the exit54, and a third passage hole78which connects the circulation hole59with the through hole74in the second disconnection state and which is disconnected by the exit-side ring valve seat62in the first disconnection state. The first passage hole76is provided in the horizontal direction at a right angle to the circulation hole59, and its central axis passes through the center of the valve ball60. The third passage hole78is provided downwardly by 45 degrees from the horizontal direction, and its central axis passes through the center of the valve ball60.

FIGS. 17 and 18show a state where the entrance52and the exit54communicate with each other through the circulation hole59of the valve ball60. When the valve shaft64is rotated by 90 degrees from this state in a counterclockwise direction with the handle72, to set the first disconnection state as shown inFIG. 19where the valve ball60disconnects the entrance52from the exit54, the entrance52, the exit54and the discharge orifice75are disconnected. When the valve shaft64is rotated by 180 degrees with the handle72from the first disconnection state, to set the second disconnection state as shown inFIG. 20, the exit54and the discharge orifice75communicate with each other through the first passage hole76, the circulation hole59, the third passage hole78and the through hole74, and remaining pressure at the exit54can be released from the discharge orifice75.

Another example embodiment of the invention is shown inFIGS. 21 to 24. A casing is formed by fastening an entrance side member53having an entrance52and an exit side member55having an exit54to a main body51with bolts56and nuts57, and a valve chamber58where the entrance52and the exit54communicate with each other is formed in the casing.

A valve ball60where a circulation hole59is formed in a straight line in a horizontal direction is rotatably provided in the valve chamber58. An entrance-side ring valve seat61is provided on the entrance52side of the valve ball60, and an exit-side ring valve seat62is provided on the exit54side of the valve ball60. The valve ball60has a parallel key groove63in its upper part, and a key member at a lower end of a valve shaft54passing through the main body51is engaged with the key groove. The valve shaft64holds airtightness with the main body51with a packing65and is fixed to the main body51with nuts66. Reference numerals67,68,69and70denote washers; and71, a packing holder. A handle72for rotation operation is fixed to the valve shaft64with nuts73.

The entrance-side ring valve seat61has a through hole74passing through from a contact surface of the valve ball60to a contact surface of the entrance side member53. The entrance side member53has a discharge orifice75with one end communicating the through hole74of the entrance-side ring valve seat61and the other end communicating ambient air. The through hole74is provided in a lower part of the entrance-side ring valve seat61in parallel to a center line of the entrance52and the exit54. The valve ball60has a first passage hole76which connects the circulation hole59with the entrance52in a first disconnection state where the valve ball60disconnects the entrance52from the exit54and which connects the circulation hole59with the exit54in a second disconnection state where the valve ball60is rotated by 180 degrees from the first disconnection state to disconnect the entrance52from the exit54, a second passage hole77which connects the circulation hole59with the through hole74in the first disconnection state and which is disconnected by the exit-side ring valve seat62in the second disconnection state, and a third passage hole78which connects the circulation hole59with the through hole74in the second disconnection state and which is disconnected by the exit-side ring valve seat62in the first disconnection state. The first passage hole76is provided in the horizontal direction at a right angle to the circulation hole59, and its central axis passes through the center of the valve ball60. The second passage hole77and the third passage hole78are respectively provided downwardly by 45 degrees from the horizontal direction, and their respective central axes pass through the center of the valve ball60.

FIGS. 21 and 22show a state where the entrance52and the exit54communicate with each other through the circulation hole59of the valve ball60. When the valve shaft64is rotated by 90 degrees from this state in a counterclockwise direction with the handle72, to set the first disconnection state as shown inFIG. 23where the valve ball60disconnects the entrance52from the exit54, the entrance52and the discharge orifice75communicate with each other through the first passage hole76, the circulation hole59, the second passage hole77and the through hole74, and fluid at the entrance52can be discharged from the discharge orifice75communicating ambient air different from the entrance52and the exit54. When the valve shaft64is rotated by 180 degrees with the handle72from the first disconnection state, to set the second disconnection state as shown inFIG. 24, the exit54and the discharge orifice75communicate with each other through the first passage hole76, the circulation hole59, the third passage hole78and the through hole74, and remaining pressure at the exit54can be released from the discharge orifice75.

In the present invention, as set forth above, fluid at the entrance can be discharged from the discharge orifice communicating ambient air different from the entrance and exit and/or remaining pressure at the exit can be released from the discharge orifice.