Systems and methods for piston check valves

A piston check valve, comprising:

• a body;
• an upstream flange;
• a downstream flange, the downstream flange being disposed opposite the upstream flange;
• a bonnet secured to the body;
• and
• a piston including a proximal end that faces the bonnet and a distal end that faces a portion of the body, the piston having a central pillar forming a narrowed portion connected between the proximal end and the distal end of the piston.

A piston check valve, comprising:

• a body;
• an upstream opening;
• a downstream opening;
• a piston having a proximal end portion and a distal end portion, the piston being secured within the body between the upstream opening and the downstream opening and being movable between a closed position and an open position;
• a resilient member biasing the piston towards the closed position;
• a retainer contacting the proximal end portion of the piston;
• and
• a removable valve seat having an opening sized to receive the distal end of the piston when the piston is in the closed position.

A piston check valve, comprising:

• a body;
• an upstream end;
• a downstream end disposed opposite the upstream end in a lateral direction;
• a piston between the upstream end and the downstream end in the lateral direction, the piston having a central pillar extending from a distal end portion of the piston;
• a retainer that surrounds the piston;
• and
• a valve seat having a ring-shaped proximal end portion that contacts the retainer, the proximal end portion of the valve seat having a sealing surface configured to contact the distal end portion of the piston when the piston check valve is closed so as to block a flow of fluid from the upstream end to the downstream end.