A plunger pump is a famous type of pump from the category of reciprocating pump. The plunger pump is a reciprocating device suitable for pumping various liquids with high solids content.

It consists of a cylinder with a cylinder equipped with a piston, consisting of a valve that controls the flow of the fluid and an extension bar that allows the piston to move inside the chamber.

These types of pumps are made of different materials. The materials used to make the plunger depend a lot on its intended use.

Ceramic pistons are suitable for grinding mortars and liquids, and other pistons use metal coatings for better performance in cases requiring high strength.

How Does Plunger Pump Work?

Most reciprocating plunger pumps use a crankshaft to move the piston back and forth during the pumping process.

The plunger in the plunger pump does not reach the cylinder wall during operation. Since the plunger pump operates on a displacement basis, there is no external seal to close the cylinder wall. The piston pack provides a fixed seal around the piston and extension rod housed in a gland.

A piston is used by the liquid end of the system to create an absorption effect. This opens the suction valve and allows fluid to flow to the metering end of the system. Subsequently, the piston moves forward.

This process changes the existing volume of the system, thereby increasing the pressure of the pumped liquid.

The outlet valve opens after the suction valve is closed, thus opening the way to the process area. This is where the fluid ends up under pressure.

In applications involving multiple pistons, the operator can manipulate the angular position of the crankshaft to ensure that pressure peaks in the system are staggered and fixed.

Types of Plunger Pumps

1) Direct-acting plunger pump

It has a piston at the liquid end (pump), which is driven directly by the pump rod (as well as the piston rod or its extension) and transmits the piston to the end of the power supply. The pump is indirectly connected by a beam or connecting rod and is connected via a piston rod to the power of an independent replacement motor.

2) Simplex plunger pump

Sometimes referred to as a single-piston reciprocating pump, it is a pump with a liquid cylinder (pump).

3) Duplex plunger pump

 It is equivalent to two single-cylinder pumps side by side on a pedestal. The driving mode of a two-pump piston/plunger is as follows: when one piston moves up, the other piston moves down and vice versa. Compared to similarly designed single-cylinder pumps, this arrangement doubles the capacity of twin-cylinder pumps.

4) Single-acting plunger pump

It is a suction type. The pump cylinder is filled only in one direction during the impact, which is called the suction stroke, and then during the return stroke, the liquid is squeezed out of the cylinder, which is called the exhaust stroke.

5) Double acting plunger pump

It is a pump that drains liquid from one end of the cylinder when one end of the cylinder is filled with liquid. In the reverse movement, the end of the newly emptied cylinder is filled, and the end of the new fill is reduced.

6) Power Pump

This plunger pump converts the rotary motion into a low-speed reciprocating motion by rotating the crankshaft coupling shaft and reducing the gear of the transverse head. The driven piston sinks from the cross member. The rod and piston structure are similar to a dual-purpose steam pump that uses higher and low-pressure metering end pressure. The high-pressure device is usually a movable piston; usually, three (three) pistons are used. Compared to single-cylinder or even twin-cylinder pumps, three or more pistons significantly reduce arterial flow.

These pumps are generally highly efficient and can generate very high pressures. They can be driven by electric motors or turbines. These pumps are relatively expensive and rarely make sense based on the performance of centrifugal pumps. However, due to the high need for steam indirect-acting piston pumps, they are often more reasonable than steam piston pumps and require a constant operation. In general, as the pumped fluid’s viscosity increases, the piston pump’s effective flow rate decreases because the pump speed must be reduced. Compared to centrifugal pumps, the pressure difference produced by reciprocating pumps has nothing to do with the density of the liquid. It depends on the amount of force applied to the piston.

Advantages of Plunger pump

  • High discharge pressure can be achieved, the flow rate is pressure independent, the adsorption performance is good, and the efficiency is high. Among them, the equivalent steam pump can reach an 80 ~ 95 flow rate.
  • In principle, any environment can be delivered without being affected by the physical or chemical properties of the environment.
  • Plunger pump operation does not change the pressure and viscosity of the transport medium.

Disadvantages of plunger pump

  1. The flow is not very stable.
  2. These reciprocating pumps have lower power than centrifugal pumps.
  3. They have a complex mechanism, and the volume of the funds is large, and it is not easy to maintain.