In-line check valve

An in-line check valve for use in a fire protection system, said valve comprising:

• an elongated, tubular valve body defining a valve cavity, an inlet end and an outlet end;
• a valve seat removably secured to said valve body at said inlet end;
• a valve piston movably disposed within said valve cavity, said piston including a generally cylindrical body defining a through bore, a seal support, arms between the body and the seal support, a removable deflector and a seal sandwiched between said deflector and said seal support, said body further defining an angled, annular impingement surface, said seal support, said arms and said impingement surface defining openings communicating with said bore;
• and
• a spring within said cavity and engaging said piston for resiliently biasing said piston toward said seat, said valve body defines a plurality of lugs extending into said cavity adjacent said inlet end, and said piston body defines a plurality of apertures alignable with said lugs and dimensioned so that said piston may be inserted into said cavity and rotated whereby the piston body engages said lugs and the piston is retained within said cavity.

A check valve comprising:

• a valve housing defining an internal cavity, an inlet to said cavity including a seat, and an outlet;
• a piston positioned in said cavity and movable between a closed position and an open position;
• a removable seal adapted to engage said seat;
• said piston including retaining means for holding said seal and a support having a support surface located on the inlet end of said piston for supporting said seal so that said seal is pressed against said seat when said piston is in said closed position, said support including a beveled surface;
• spring means for resiliently biasing said piston toward said closed position, said spring means being preloaded so that a given cracking pressure is required to open said valve;
• and
• wherein said piston includes an impingement surface impinged on by fluid flowing through said valve so that fluid flowing through said valve moves the piston toward an open position, said impingement surface being generally circular, inwardly beveled and extending in spaced, substantially parallel relationship to said beveled surface of said support, and wherein the differential pressure across said valve within a given flow range is less than the initial cracking differential pressure.

A check valve comprising:

• a valve housing defining an internal cavity, an inlet to said cavity including a seat and an outlet;
• a piston positioned in said cavity and movable between a closed position and an open position;
• a removable seal adapted to engage said seat;
• said piston including retaining means for holding said seal and a support surface located on the inlet end of said piston for supporting said seal so that said seal is pressed against said seat when said piston is in said closed position;
• spring means for resiliently biasing said piston toward said closed position, said spring means being preloaded so that a given cracking pressure is required to open said valve;
• wherein said piston includes a deflecting surface impinged on by fluid flowing through said valve so that fluid flowing through said valve moves the piston toward an open position and wherein the differential pressure across said valve within a given flow range is less than the initial cracking differential pressure, said valve housing including a removable end cover, said end cover including said seat and being removable permitting said piston to be removed from said cavity;
• and
• means for retaining said piston within said cavity upon removal of said end cover, said means for retaining said piston including abutments in said internal cavity of said housing, and said piston defines a plurality of apertures positioned to allow said piston to be inserted into said internal cavity and against said spring means with said abutments slipping through said apertures.