How does a high-pressure pump work? The function and design of the oscillating displacement pump
Oscillating displacement pumps are high-pressure pumps that move liquids by alternating pressure and suction phases. There are two types of oscillating displacement pumps: piston pumps, with a movable seal, and plunger pumps, with a fixed seal. KAMAT manufactures plunger pumps.
A high-pressure plunger pump is used for pumping liquids under high pressure. It works on the volumetric displacement principle, where the liquid flow is generated by alternating pressure and suction phases. Driving the piston increases the pressure in the cylinder, causing the liquid to be expelled through the discharge valve.
The high pressure-pump consists of a drive part (gear) and a fluid-carrying part (pump head) in which several pistons (3 or 5) are mechanically driven by a crankshaft. During the suction stroke, the inlet valve opens and the space in front of the pistons fills with water. During the pressure stroke, the plunger pushes this volume of water through the outlet valve into the pressure line of the pump. Each stroke of the piston always moves the same volume of water per piston. The efficiency of the valves largely determines the efficiency of the high pressure pump.
Most machines that can drive a plunger pump, such as internal combustion engines and electric motors, produce rotary motion. In order to use rotating prime movers, these high pressure pumps are typically equipped with a drive journal with a crankshaft, connecting rods and crossheads. As with a car engine, a rotary motion is converted into an oscillating motion, but in the opposite direction. Since the prime movers generate higher speeds than are normally required for plunger pumps, it is often necessary to use gearboxes. It is advisable to integrate these into the drive section of the pump.
The higher the drive speed, the higher the number of cycles per minute and the higher the flow rate. A high-pressure plunger pump can, in principle, increase the water pressure indefinitely. The maximum permissible operating pressure of the high-pressure plunger pump is determined by the design and choice of materials.