When the piston or plunger moves from left to right, the inside of the pump cylinder volume increases, pressure with lower, into the pipe of liquid pressure is greater than the pressure in the pump cylinder, liquid under the action of pressure difference, open the suction valve and into the pump cylinder. The piston moves to the left after the crank of the gearbox turns 180 degrees. Basic due to low temperature liquid is incompressible, the cryogenic liquid was immediately piston compressor and pressure rise rapidly, at the same time from the sealing parts (from Detroit piston ring or the clearance between the pump cylinder and plunger) reveal that the cryogenic liquid quantity will increase, will make the speed of the pump cylinder pressure increases a little bit small, but still pressure has been on the rise. Until the liquid pressure in the pump tank is large enough to open the discharge valve, the cryogenic liquid passes through the discharge valve to the drain pipe. Repeat the process when the piston is pulled by the crank and moved to the right.
The first half cycle of the reciprocating cryogenic pump is the inhalation of cryogenic liquid, and the latter half of the period is the discharge of cryogenic liquid. Drainage is discontinuous, not continuous.
The hydraulic ends mainly include discharge valve, suction valve (or suction window), pump cylinder and cylinder sleeve, piston (or plunger), seal, various connecting pipe and compensating pipe. These parts are exposed to cryogenic liquids, usually copper, stainless steel and polytetrafluoroethylene and other low-temperature materials, and attention to remove grease, waterproof, to prevent foreign body entry.