Reciprocating pump

A reciprocating pump for delivering liquefied gas, comprising:

• a cylinder having an inflow chamber, a reset chamber, an intermediate chamber, and a pressurizing chamber therein;
• a piston located in the cylinder;
• a first seal, a second seal, and a third seal arranged in a gap between an inner surface of the cylinder and an outer surface of the piston;
• a suction check valve coupled to a suction port of the cylinder;
• an inlet check valve and an outlet check valve disposed in a piston passage extending through the piston;
• a discharge check valve coupled to a discharge port of the cylinder;
• and
• a leakage discharge check valve coupled to a leakage discharge port of the cylinder,
• wherein the leakage discharge port communicates with the reset chamber,
• the inflow chamber and the reset chamber are partitioned by the first seal,
• the reset chamber and the intermediate chamber are partitioned by the second seal,
• the intermediate chamber and the pressurizing chamber are partitioned by the third seal, and
• the piston has a communication passage that provides a fluid communication between the piston passage and the intermediate chamber.