Piston Pump

A reciprocating piston inside a cylinder sucks a fluid into the chamber in one stroke and discharges it in the other. Inlet and discharge valves open and close with the varying pressure changes inside the cylinder. As the piston lifts, a negative pressure is created, opening the inlet valve, drawing fluid in and closing the discharge valve. When the piston drops the discharge valve opens, the inlet valve closes and the fluid is pushed out of the now open discharge valve.