Reciprocating pump is a kind of volumetric pump, which depends on the reciprocating static of piston in the pump cylinder, so that the volume of the pump cylinder is periodically expanded and reduced to absorb the liquid. The reciprocating system has the ability of self-priming, and it can still maintain the same amount of flux under the drastic change of pressure. It is especially useful for the liquid with large viscosity in the condition of small flow and low vertical. In the oil tank, the important use of reciprocating pump is to guarantee the special fuel oil and smooth oil pump, and can also be used as boiler feed pump or centrifugal pump to pump vacuum primer, pump bottom oil and so on. Because reciprocating pump structure is complex, vulnerable parts, flow has pulsation, large flow opportunity is light, so in many places for centrifugal pump. However, with regard to low pressure, low flow rate, and large viscosity of the liquid, the demand for accurate measurement and flow with the pressure change small factory still adopt various reciprocating pump.
The first. Piston pump
The piston pump is practical for the low pressure head. The piston rod is connected by the crosshead with the crank connecting rod mechanism. When the original motive forces the crank to rotate for a week, the piston moves back and forth in the pump cylinder. The maximum interval for moving a piston is called a stroke.
If the piston reciprocates once, as long as the side of pump cylinder is inhaled and discharged once liquid, this kind of pump is called single acting pump. Single action pump drainage is continuous, the liquid is not drained, the drainage is not liquid. At the same time, the non-uniform velocity of the piston in a straight line is not uniform, even when the fluid is drained.
In order to eliminate the continuity of the single-acting pump drainage, a double acting pump has emerged. The dual action pump has at least four valves, the separation is installed on both sides of the pump cylinder, and the suction pipe and the discharge pipe break up on both sides. Thus, when the original motive is running, one side of the suction, the drainage and the other side of the holding fluid, the suction fluid, the suction pipe and the discharge of the fluid in the tube will remain active.
In the second. Plunger pump
The piston of the pump is important for mechanical strength due to the column type. For pump under low pressure head to send liquid, don't just consider the strength of the pump cylinder, but also to consider the strength of the piston, so individual used in low pressure pump plunger pump and medium pressure pumps, piston pump is used for low pressure pump.
Three plunger type low pressure pump is a kind of triple pump. The triple pump is composed of three single acting pumps that share one crankshaft. Three single pump crank staggered 120 °, the pipettes and drainage tube is a sharing three pump. In this way, during the rotation of the crankshaft for a week, the suction and drainage of each pump are in a phase difference of 1 to 3 cycles, and the average quality of the flow in the drainage tube is greatly improved.
In the third. Divide the pump
In order to prevent the piston from being damaged by the corrosive liquid or suspension, the pump is used to separate the plunger and the reciprocating pump separated by a flexible film. All parts on the left side can be made of acid-proof material or lined with acid-proof materials. On the right side, there is water or oil. When the plunger is reciprocated, it forces the gap to turn alternately to both sides, causing the gap to be the same as the pistons' suction and drainage, while the liquid is kept away from the plunger.