What is the Difference Between Piston and Plunger?

The main difference between piston and plunger pumps lies in the high-pressure seal and the way they operate. Here are the key differences:

1. High-Pressure Seal: In a piston pump, the high-pressure seal is attached to and reciprocates along with the piston, while in a plunger pump, the high-pressure seal is stationary.
2. Operating Pressure: Plunger pumps can produce higher pressure than piston pumps due to their stationary seal. Plunger pumps are suitable for high-pressure industrial applications, such as removing graffiti, cleaning heavy-duty industrial vehicles, or washing down surfaces. Piston pumps, on the other hand, are more suitable for residential use, such as washing cars or houses.
3. Piston Fit: Unlike a piston that fits tightly inside the cylinder, a plunger fits loosely.
4. Number of ActingEnds: Plunger pumps are single-acting, meaning only one end of the plunger is used in pumping the liquid. Piston pumps may be double-acting.
5. Duty Cycle: Piston pumps are best suited for short duty cycles unless a larger pump operates slowly, while plunger pumps are suitable for continuous operation when run slowly.

In summary, plunger pumps are better suited for high-pressure applications due to their stationary seal and ability to produce higher pressure. Piston pumps, with their moving seals and higher friction, are more suitable for lower-pressure applications.

Comparative Table: Piston vs Plunger

The main difference between piston and plunger pumps lies in the design and function of their components. Here is a table comparing the two types of pumps:

Piston pumps are positive displacement pumps where fluid movement is created by a piston. They are often used in gas compressors, reciprocating engines, pneumatic cylinders, and reciprocating pumps. On the other hand, plunger pumps have a plunger that slides back and forth within a stuffing box, increasing and decreasing the working volume. They are better suited for high-pressure applications, as seals are stationary within the pump, unlike piston designs where the seal slides within a hollow chamber.