Abstract:
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.

Description:
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&#39;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. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1 . is a transverse sectional view of the ball valve according to an example embodiment of the present invention; 
       FIG. 2 . is a central sectional view of  FIG. 1 ; 
       FIG. 3 . is a central sectional view of  FIG. 1  when the valve ball in  FIG. 1  is rotated by 90 degrees in the counterclockwise direction to set the first disconnection state; 
       FIG. 4 . is a central sectional view of  FIG. 1  when the valve ball in  FIG. 1  is rotated by 90 degrees in the clockwise direction to set the second disconnection state; 
       FIG. 5 . is a transverse sectional view of the ball valve according to another example embodiment of the present invention; 
       FIG. 6 . is a central sectional view of  FIG. 5 ; 
       FIG. 7 . is a central sectional view of  FIG. 5  when the valve ball in  FIG. 5  is rotated by 90 degrees in the counterclockwise direction to set the first disconnection state; 
       FIG. 8 . is a central sectional view of  FIG. 5  when the valve ball in  FIG. 5  is rotated by 90 degrees in the clockwise direction to set the second disconnection state; 
       FIG. 9 . is a transverse sectional view of the ball valve according to another example embodiment of the present invention; 
       FIG. 10 . is a central sectional view of  FIG. 9 ; 
       FIG. 11 . is a central sectional view of  FIG. 9  when the valve ball in  FIG. 9  is rotated by 90 degrees in the counterclockwise direction to set the first disconnection state; 
       FIG. 12 . is a central sectional view of  FIG. 9  when the valve ball in  FIG. 9  is rotated by 90 degrees in the clockwise direction to set the second disconnection state; 
       FIG. 13 . is a transverse sectional view of the ball valve according to another example embodiment of the present invention; 
       FIG. 14 . is a central sectional view of  FIG. 13 ; 
       FIG. 15 . is a central sectional view of  FIG. 13  when the valve ball in  FIG. 13  is rotated by 90 degrees in the counterclockwise direction to set the first disconnection state; 
       FIG. 16 . is a central sectional view of  FIG. 13  when the valve ball in  FIG. 13  is rotated by 90 degrees in the clockwise direction to set the second disconnection state; 
       FIG. 17 . is a transverse sectional view of the ball valve according to another example embodiment of the present invention; 
       FIG. 18 . is a central sectional view of  FIG. 17 ; 
       FIG. 19 . is a central sectional view of  FIG. 17  when the valve ball in  FIG. 17  is rotated by 90 degrees in the counterclockwise direction to set the first disconnection state; 
       FIG. 20 . is a central sectional view of  FIG. 17  when the valve ball in  FIG. 17  is rotated by 90 degrees in the clockwise direction to set the second disconnection state; 
       FIG. 21 . is a transverse sectional view of the ball valve according to another example embodiment of the present invention; 
       FIG. 22 . is a central sectional view of  FIG. 21 ; 
       FIG. 23 . is a central sectional view of  FIG. 21  when the valve ball in  FIG. 21  is rotated by 90 degrees in the counterclockwise direction to set the first disconnection state; and 
       FIG. 24 . is a central sectional view of  FIG. 21  when the valve ball in  FIG. 21  is rotated by 90 degrees in the clockwise direction to set the second disconnection state. 
   

   DETAILED DESCRIPTION 
   An example embodiment of the invention is shown in  FIGS. 1 to 4 . A casing is formed by fastening an entrance side member  3  having an entrance  2  and an exit side member  5  having an exit  4  to a main body  1  with bolts  6  and nuts  7 , and a valve chamber  8  where the entrance  2  and the exit  4  communicate with each other is formed in the casing. 
   A valve ball  10  where a circulation hole  9  is formed in a straight line in a horizontal direction is rotatably provided in the valve chamber  8 . An entrance-side ring valve seat  11  is provided on the entrance  2  side of the valve ball  10 , and an exit-side ring valve seat  12  is provided on the exit  4  side of the valve ball  10 . The valve ball  10  has a parallel key groove  13  in its upper part, and a key member at a lower end of a valve shaft  14  passing through the main body  1  is engaged with the key groove. The valve shaft  14  holds airtightness with the main body  1  with a packing  15  and is fixed to the main body  1  with nuts  16 . Reference numerals  17 ,  18 ,  19  and  20  denote washers; and  21 , a packing holder. A handle  22  for rotation operation is fixed to the valve shaft  14  with nuts  23 . 
   The exit-side ring valve seat  12  has a through hole  24  passing through from a contact surface of the valve ball  10  to a contact surface of the exit side member  5 . The exit side member  5  has a discharge orifice  25  with one end communicating the through hole  24  of the exit-side ring valve seat  12  and the other end communicating ambient air. The through hole  24  is provided in a lower part of the exit-side ring valve seat  12  in parallel to a center line of the entrance  2  and the exit  4 . The valve ball  10  has a first passage hole  26  which connects the circulation hole  9  with the entrance  2  in a first disconnection state where the valve ball  10  disconnects the entrance  2  from the exit  4 , and which connects the circulation hole  9  with the exit  4  in a second disconnection state where the valve ball  10  is rotated by 180 degrees from the first disconnection state to disconnect the entrance  2  from the exit  4 , and a second passage hole  27  which connects the circulation hole  9  with the through hole  24  in the first disconnection state and which is disconnected by the entrance-side ring valve seat  11  in the second disconnection state. The first passage hole  26  is provided in the horizontal direction at a right angle to the circulation hole  9 , and its central axis passes through the center of the valve ball  10 . The second passage hole  27  is provided downwardly by 45 degrees from the horizontal direction, and its central axis passes through the center of the valve ball  10 . 
     FIGS. 1 and 2  show a state where the entrance  2  and the exit  4  communicate with each other through the circulation hole  9  of the valve ball  10 . When the valve shaft  14  is rotated by 90 degrees from this state in a counterclockwise direction with the handle  22 , to set the first disconnection state as shown in  FIG. 3  where the valve ball  10  disconnects the entrance  2  from the exit  4 , the entrance  2  and the discharge orifice  25  communicate with each other through the first passage hole  26 , the circulation hole  9 , the second passage hole  27  and the through hole  24 , and fluid at the entrance  2  can be discharged from the discharge orifice  25  communicating ambient air different from the entrance  2  and the exit  4 . When the valve shaft  14  is rotated by 180 degrees with the handle  22  from the first disconnection state, to set the second disconnection state as shown in  FIG. 4 , the entrance  2 , the exit  4  and the discharge orifice  25  are disconnected. 
   Another example embodiment of the invention is shown in  FIGS. 5 to 8 . A casing is formed by fastening an entrance side member  3  having an entrance  2  and an exit side member  5  having an exit  4  to a main body  1  with bolts  6  and nuts  7 , and a valve chamber  8  where the entrance  2  and the exit  4  communicate with each other is formed in the casing. 
   A valve ball  10  where a circulation hole  9  is formed in a straight line in a horizontal direction is rotatably provided in the valve chamber  8 . An entrance-side ring valve seat  11  is provided on the entrance  2  side of the valve ball  10 , and an exit-side ring valve seat  12  is provided on the exit  4  side of the valve ball  10 . The valve ball  10  has a parallel key groove  13  in its upper part, and a key member at a lower end of a valve shaft  14  passing through the main body  1  is engaged with the key groove. The valve shaft  14  holds airtightness with the main body  1  with a packing  15  and is fixed to the main body  1  with nuts  16 . Reference numerals  17 ,  18 ,  19  and  20  denote washers; and  21 , a packing holder. A handle  22  for rotation operation is fixed to the valve shaft  14  with nuts  23 . 
   The exit-side ring valve seat  12  has a through hole  24  passing through from a contact surface of the valve ball  10  to a contact surface of the exit side member  5 . The exit side member  5  has a discharge orifice  25  with one end communicating the through hole  24  of the exit-side ring valve seat  12  and the other end communicating ambient air. The through hole  24  is provided in a lower part of the exit-side ring valve seat  12  in parallel to a center line of the entrance  2  and the exit  4 . The valve ball  10  has a first passage hole  26  which connects the circulation hole  9  with the entrance  2  in a first disconnection state where the valve ball  10  disconnects the entrance  2  from the exit  4 , and which connects the circulation hole  9  with the exit  4  in a second disconnection state where the valve ball  10  is rotated by 180 degrees from the first disconnection state to disconnect the entrance  2  from the exit  4 , and a third passage hole  28  which connects the circulation hole  9  with the through hole  24  in the second disconnection state and which is disconnected by the entrance-side ring valve seat  11  in the first disconnection state. The first passage hole  26  is provided in the horizontal direction at a right angle to the circulation hole  9 , and its central axis passes through the center of the valve ball  10 . The third passage hole  28  is provided downwardly by 45 degrees from the horizontal direction, and its central axis passes through the center of the valve ball  10 . 
     FIGS. 5 and 6  show a state where the entrance  2  and the exit  4  communicate with each other through the circulation hole  9  of the valve ball  10 . When the valve shaft  14  is rotated by 90 degrees from this state in a counterclockwise direction with the handle  22 , to set the first disconnection state as shown in  FIG. 7  where the valve ball  10  disconnects the entrance  2  from the exit  4 , the entrance  2 , the exit  4  and the discharge orifice  25  are disconnected. When the valve shaft  14  is rotated by 180 degrees with the handle  22  from the first disconnection state, to set the second disconnection state as shown in  FIG. 8 , the exit  4  and the discharge orifice  25  communicate with each other through the first passage hole  26 , the circulation hole  9 , the third passage hole  28  and the through hole  24 , and remaining pressure at the exit  4  can be released from the discharge orifice  25 . 
   Another example embodiment of the invention is shown in  FIGS. 9 to 12 . A casing is formed by fastening an entrance side member  3  having an entrance  2  and an exit side member  5  having an exit  4  to a main body  1  with bolts  6  and nuts  7 , and a valve chamber  8  where the entrance  2  and the exit  4  communicate with each other is formed in the casing. 
   A valve ball  10  where a circulation hole  9  is formed in a straight line in a horizontal direction is rotatably provided in the valve chamber  8 . An entrance-side ring valve seat  11  is provided on the entrance  2  side of the valve ball  10 , and an exit-side ring valve seat  12  is provided on the exit  4  side of the valve ball  10 . The valve ball  10  has a parallel key groove  13  in its upper part, and a key member at a lower end of a valve shaft  14  passing through the main body  1  is engaged with the key groove. The valve shaft  14  holds airtightness with the main body  1  with a packing  15  and is fixed to the main body  1  with nuts  16 . Reference numerals  17 ,  18 ,  19  and  20  denote washers; and  21 , a packing holder. A handle  22  for rotation operation is fixed to the valve shaft  14  with nuts  23 . 
   The exit-side ring valve seat  12  has a through hole  24  passing through from a contact surface of the valve ball  10  to a contact surface of the exit side member  5 . The exit side member  5  has a discharge orifice  25  with one end communicating the through hole  24  of the exit-side ring valve seat  12  and the other end communicating ambient air. The through hole  24  is provided in a lower part of the exit-side ring valve seat  12  in parallel to a center line of the entrance  2  and the exit  4 . The valve ball  10  has a first passage hole  26  which connects the circulation hole  9  with the entrance  2  in a first disconnection state where the valve ball  10  disconnects the entrance  2  from the exit  4 , and which connects the circulation hole  9  with the exit  4  in a second disconnection state where the valve ball  10  is rotated by 180 degrees from the first disconnection state to disconnect the entrance  2  from the exit  4 , a second passage hole  27  which connects the circulation hole  9  with the through hole  24  in the first disconnection state and which is disconnected by the entrance-side ring valve seat  11  in the second disconnection state, and a third passage hole  28  which connects the circulation hole  9  with the through hole  24  in the second disconnection state and which is disconnected by the entrance-side ring valve seat  11  in the first disconnection state. The first passage hole  26  is provided in the horizontal direction at a right angle to the circulation hole  9 , and its central axis passes through the center of the valve ball  10 . The second passage hole  27  and the third passage hole  28  are respectively provided downwardly by 45 degrees from the horizontal direction, and their respective central axes pass through the center of the valve ball  10 . 
     FIGS. 9 and 10  show a state where the entrance  2  and the exit  4  communicate with each other through the circulation hole  9  of the valve ball  10 . When the valve shaft  14  is rotated by 90 degrees from this state in a counterclockwise direction with the handle  22 , to set the first disconnection state as shown in  FIG. 11  where the valve ball  10  disconnects the entrance  2  from the exit  4 , the entrance  2  and the discharge orifice  25  communicate with each other through the first passage hole  26 , the circulation hole  9 , the second passage hole  27  and the through hole  24 , and fluid at the entrance  2  can be discharged from the discharge orifice  25  communicating ambient air different from the entrance  2  and the exit  4 . When the valve shaft  14  is rotated by 180 degrees with the handle  22  from the first disconnection state, to set the second disconnection state as shown in  FIG. 12 , the exit  4  and the discharge orifice  25  communicate with each other through the first passage hole  26 , the circulation hole  9 , the third passage hole  28  and the through hole  24 , and remaining pressure at the exit  4  can be released from the discharge orifice  25 . 
   Another example embodiment of the invention is shown in  FIGS. 13 to 16 . A casing is formed by fastening an entrance side member  53  having an entrance  52  and an exit side member  55  having an exit  54  to a main body  51  with bolts  56  and nuts  57 , and a valve chamber  58  where the entrance  52  and the exit  54  communicate with each other is formed in the casing. 
   A valve ball  60  where a circulation hole  59  is formed in a straight line in a horizontal direction is rotatably provided in the valve chamber  58 . An entrance-side ring valve seat  61  is provided on the entrance  52  side of the valve ball  60 , and an exit-side ring valve seat  62  is provided on the exit  54  side of the valve ball  60 . The valve ball  60  has a parallel key groove  63  in its upper part, and a key member at a lower end of a valve shaft  54  passing through the main body  51  is engaged with the key groove. The valve shaft  64  holds airtightness with the main body  51  with a packing  65  and is fixed to the main body  51  with nuts  66 . Reference numerals  67 ,  68 ,  69  and  70  denote washers; and  71 , a packing holder. A handle  72  for rotation operation is fixed to the valve shaft  64  with nuts  73 . 
   The entrance-side ring valve seat  61  has a through hole  74  passing through from a contact surface of the valve ball  60  to a contact surface of the entrance side member  53 . The entrance side member  53  has a discharge orifice  75  with one end communicating the through hole  74  of the entrance-side ring valve seat  61  and the other end communicating ambient air. The through hole  74  is provided in a lower part of the entrance-side ring valve seat  61  in parallel to a center line of the entrance  52  and the exit  54 . The valve ball  60  has a first passage hole  76  which connects the circulation hole  59  with the entrance  52  in a first disconnection state where the valve ball  60  disconnects the entrance  52  from the exit  54 , and which connects the circulation hole  59  with the exit  54  in a second disconnection state where the valve ball  60  is rotated by 180 degrees from the first disconnection state to disconnect the entrance  52  from the exit  54 , and a second passage hole  77  which connects the circulation hole  59  with the through hole  74  in the first disconnection state and which is disconnected by the exit-side ring valve seat  62  in the second disconnection state. The first passage hole  76  is provided in the horizontal direction at a right angle to the circulation hole  59 , and its central axis passes through the center of the valve ball  60 . The second passage hole  77  is provided downwardly by 45 degrees from the horizontal direction, and its central axis passes through the center of the valve ball  60 . 
     FIGS. 13 and 14  show a state where the entrance  52  and the exit  54  communicate with each other through the circulation hole  59  of the valve ball  60 . When the valve shaft  64  is rotated by 90 degrees from this state in a counterclockwise direction with the handle  72 , to set the first disconnection state as shown in  FIG. 15  where the valve ball  60  disconnects the entrance  52  from the exit  54 , the entrance  52  and the discharge orifice  75  communicate with each other through the first passage hole  76 , the circulation hole  59 , the second passage hole  77  and the through hole  74 , and fluid at the entrance  52  can be discharged from the discharge orifice  75  communicating ambient air different from the entrance  52  and the exit  54 . When the valve shaft  64  is rotated by 180 degrees with the handle  72  from the first disconnection state, to set the second disconnection state as shown in  FIG. 16 , the entrance  52 , the exit  54  and the discharge orifice  75  are disconnected. 
   Another example embodiment of the invention is shown in  FIGS. 17 to 20 . A casing is formed by fastening an entrance side member  53  having an entrance  52  and an exit side member  55  having an exit  54  to a main body  51  with bolts  56  and nuts  57 , and a valve chamber  58  where the entrance  52  and the exit  54  communicate with each other is formed in the casing. 
   A valve ball  60  where a circulation hole  59  is formed in a straight line in a horizontal direction is rotatably provided in the valve chamber  58 . An entrance-side ring valve seat  61  is provided on the entrance  52  side of the valve ball  60 , and an exit-side ring valve seat  62  is provided on the exit  54  side of the valve ball  60 . The valve ball  60  has a parallel key groove  63  in its upper part, and a key member at a lower end of a valve shaft  54  passing through the main body  51  is engaged with the key groove. The valve shaft  64  holds airtightness with the main body  51  with a packing  65  and is fixed to the main body  51  with nuts  66 . Reference numerals  67 ,  68 ,  69  and  70  denote washers; and  71 , a packing holder. A handle  72  for rotation operation is fixed to the valve shaft  64  with nuts  73 . 
   The entrance-side ring valve seat  61  has a through hole  74  passing through from a contact surface of the valve ball  60  to a contact surface of the entrance side member  53 . The entrance side member  53  has a discharge orifice  75  with one end communicating the through hole  74  of the entrance-side ring valve seat  61  and the other end communicating ambient air. The through hole  74  is provided in a lower part of the entrance-side ring valve seat  61  in parallel to a center line of the entrance  52  and the exit  54 . The valve ball  60  has a first passage hole  76  which connects the circulation hole  59  with the entrance  52  in a first disconnection state where the valve ball  60  disconnects the entrance  52  from the exit  54 , and which connects the circulation hole  59  with the exit  54  in a second disconnection state where the valve ball  60  is rotated by 180 degrees from the first disconnection state to disconnect the entrance  52  from the exit  54 , and a third passage hole  78  which connects the circulation hole  59  with the through hole  74  in the second disconnection state and which is disconnected by the exit-side ring valve seat  62  in the first disconnection state. The first passage hole  76  is provided in the horizontal direction at a right angle to the circulation hole  59 , and its central axis passes through the center of the valve ball  60 . The third passage hole  78  is provided downwardly by 45 degrees from the horizontal direction, and its central axis passes through the center of the valve ball  60 . 
     FIGS. 17 and 18  show a state where the entrance  52  and the exit  54  communicate with each other through the circulation hole  59  of the valve ball  60 . When the valve shaft  64  is rotated by 90 degrees from this state in a counterclockwise direction with the handle  72 , to set the first disconnection state as shown in  FIG. 19  where the valve ball  60  disconnects the entrance  52  from the exit  54 , the entrance  52 , the exit  54  and the discharge orifice  75  are disconnected. When the valve shaft  64  is rotated by 180 degrees with the handle  72  from the first disconnection state, to set the second disconnection state as shown in  FIG. 20 , the exit  54  and the discharge orifice  75  communicate with each other through the first passage hole  76 , the circulation hole  59 , the third passage hole  78  and the through hole  74 , and remaining pressure at the exit  54  can be released from the discharge orifice  75 . 
   Another example embodiment of the invention is shown in  FIGS. 21 to 24 . A casing is formed by fastening an entrance side member  53  having an entrance  52  and an exit side member  55  having an exit  54  to a main body  51  with bolts  56  and nuts  57 , and a valve chamber  58  where the entrance  52  and the exit  54  communicate with each other is formed in the casing. 
   A valve ball  60  where a circulation hole  59  is formed in a straight line in a horizontal direction is rotatably provided in the valve chamber  58 . An entrance-side ring valve seat  61  is provided on the entrance  52  side of the valve ball  60 , and an exit-side ring valve seat  62  is provided on the exit  54  side of the valve ball  60 . The valve ball  60  has a parallel key groove  63  in its upper part, and a key member at a lower end of a valve shaft  54  passing through the main body  51  is engaged with the key groove. The valve shaft  64  holds airtightness with the main body  51  with a packing  65  and is fixed to the main body  51  with nuts  66 . Reference numerals  67 ,  68 ,  69  and  70  denote washers; and  71 , a packing holder. A handle  72  for rotation operation is fixed to the valve shaft  64  with nuts  73 . 
   The entrance-side ring valve seat  61  has a through hole  74  passing through from a contact surface of the valve ball  60  to a contact surface of the entrance side member  53 . The entrance side member  53  has a discharge orifice  75  with one end communicating the through hole  74  of the entrance-side ring valve seat  61  and the other end communicating ambient air. The through hole  74  is provided in a lower part of the entrance-side ring valve seat  61  in parallel to a center line of the entrance  52  and the exit  54 . The valve ball  60  has a first passage hole  76  which connects the circulation hole  59  with the entrance  52  in a first disconnection state where the valve ball  60  disconnects the entrance  52  from the exit  54  and which connects the circulation hole  59  with the exit  54  in a second disconnection state where the valve ball  60  is rotated by 180 degrees from the first disconnection state to disconnect the entrance  52  from the exit  54 , a second passage hole  77  which connects the circulation hole  59  with the through hole  74  in the first disconnection state and which is disconnected by the exit-side ring valve seat  62  in the second disconnection state, and a third passage hole  78  which connects the circulation hole  59  with the through hole  74  in the second disconnection state and which is disconnected by the exit-side ring valve seat  62  in the first disconnection state. The first passage hole  76  is provided in the horizontal direction at a right angle to the circulation hole  59 , and its central axis passes through the center of the valve ball  60 . The second passage hole  77  and the third passage hole  78  are respectively provided downwardly by 45 degrees from the horizontal direction, and their respective central axes pass through the center of the valve ball  60 . 
     FIGS. 21 and 22  show a state where the entrance  52  and the exit  54  communicate with each other through the circulation hole  59  of the valve ball  60 . When the valve shaft  64  is rotated by 90 degrees from this state in a counterclockwise direction with the handle  72 , to set the first disconnection state as shown in  FIG. 23  where the valve ball  60  disconnects the entrance  52  from the exit  54 , the entrance  52  and the discharge orifice  75  communicate with each other through the first passage hole  76 , the circulation hole  59 , the second passage hole  77  and the through hole  74 , and fluid at the entrance  52  can be discharged from the discharge orifice  75  communicating ambient air different from the entrance  52  and the exit  54 . When the valve shaft  64  is rotated by 180 degrees with the handle  72  from the first disconnection state, to set the second disconnection state as shown in  FIG. 24 , the exit  54  and the discharge orifice  75  communicate with each other through the first passage hole  76 , the circulation hole  59 , the third passage hole  78  and the through hole  74 , and remaining pressure at the exit  54  can be released from the discharge orifice  75 . 
   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.