Most Common Types of Positive Displacement Pumps

Positive displacement pumps operate by trapping and moving a fixed amount of fluid through the pump’s housing with each cycle. Unlike dynamic pumps, they create flow using reciprocating, rotary, or diaphragm actions. These pumps are known for their ability to deliver a consistent flow rate, even at high pressures. 

They are commonly used in oil and gas, chemical, food and beverage, and wastewater treatment industries. To know more about positive displacement pumps in detail head out to our website. 

Table of contents:

• Types of positive displacement reciprocating pumps
• Types of positive displacement rotary pumps
• Why choose DAE Pumps?
• Final words
• Frequently asked questions (FAQs) about positive displacement pumps

All types of positive displacement pumps involve a mechanism that falls into two categories depending on the type of motion it utilizes. These two categories of pump movement types are called reciprocating and rotary.

Types of positive displacement reciprocating pumps

A reciprocating pump is a specific category of positive displacement pump that functions by using a reciprocating motion to effectively displace fluid. 

DAE reciprocating pumps

Diaphragm pump:

Diaphragm pump works by utilizing a flexible elastomer cover or diaphragm to displace fluid. When the diaphragm expands, it draws fluid into the pump and when it contracts, it delivers the fluid out of the discharge side of the pump. It utilizes check valves to ensure a one-way flow. Diaphragm pumps do not require any seal because the wet and dry sections of the pump are completely separate from each other. 

Piston pump (axial piston pump):

The mechanism consists of a reciprocating piston inside of a cylinder with check valves at both the intake and discharge. When the piston is on the suction stroke, the chamber inside of the cylinder expands. In this action, the pressure drops and the pressure valve on the suction side opens. This allows the fluid to flow through the intake. On the discharge stroke, the piston pushes on the fluid in the cylinder, raising the pressure. It closes the suction valve, and opens the discharge valve, pushing the fluid out. 

Plunger pump:

Plunger pumps operate on the same working principle as piston pumps, but with a different design. They are widely recognised for their exceptional capability to generate and maintain high pressures while ensuring accurate and controlled flow rates. These devices are used in various critical pump applications like high-pressure water jetting, hydrostatic testing, oil and gas production, car wash systems, and high-pressure cleaning. 

Types of positive displacement rotary pumps

Positive displacement rotary pumps utilize rotating mechanisms to displace fluid. These pumps trap fluid inside the pump casing. Then they move it from the intake to the discharge side due to their rotary motion.

DAE rotary positive displacement pumps

Screw pump:

Screw pumps may have single or multiple shafts with extensive threads on them. The rotating shaft looks like a screw and therefore, it is called a screw pump. It operates at low RPM. As the shaft rotates in the pump housing, fluid is trapped in the gaps between the screw threads and moves along the length of the housing. It is then delivered to the discharge outlet. The pump selection is based on handling fluids with high viscosity like slurries, and solids-laden liquids.

Peristaltic pump:

Peristaltic pumps contain fluid trapped in a flexible hose. The hose is pressed between the rollers and the inside wall of the pump housing. As the rollers revolve, they squeeze the fluid through the tubes towards the discharge outlet. Peristaltic pumps are generally used in pharmaceuticals, biotechnology, food and beverage, water treatment, and chemical processing industries. Such pumps can handle shear-sensitive, corrosive, or abrasive fluids.

Vane pump:

Vane pumps’ rotor contains a series of slots for sliding vanes. When the rotor spins, the vanes press against the housing. Since the rotor is offset within the housing, the vanes extend and retract during rotation. The fluid is captured between the vanes as they rotate, and directed to the discharge. 

Gear pump:

The gear pump utilizes a pair of rotating gears inside the pump housing. The rotors move and push the fluid out towards the discharge end of the pump. As the gears rotate, it traps fluid between the gear teeth and the inside wall of the pump. The trapped fluid is then pushed in the direction the gear is spinning, eventually releasing out of the other side. Gear pumps can generally be built in two different ways; an external gear pump and an internal gear pump. 

Lobe pump:

Lobe pumps look and function quite similar to gear pumps. In lobe pumps, the rotors are driven independently by external timing gears. The rotors have two or more lobes that rotate and trap fluid between the lobes, forcing fluid through the discharge outlet on each rotation. 

Types of positive displacement pumps

Why choose DAE Pumps?

DAE Pumps manufactures premium quality positive displacement pumps for various industrial and commercial use. The high-quality materials ensure minimum maintenance and wear and tear of pumps.  

Final words

Positive displacement pumps are very helpful in any business that needs to move fluids efficiently and carefully. This includes oil and gas exploration, chemical processing, and water treatment industries. Their ability to give precise flow rates, handle difficult fluids, and keep performing well makes them stand out as reliable workhorses. 

For the right selection of positive displacement pumps for pulp and paper, sewage treatment, and mining industries, call DAE Pumps at (760) 477-4224. You can also contact us for a free sales quote.

Frequently asked questions about positive displacement pumps

1: What is the difference between positive displacement pumps and centrifugal pumps?

Positive displacement pumps capture and displace a fixed amount of fluid, giving a consistent flow rate and high pressures. Centrifugal pumps generate large flows but low pressures. Centrifugal pumps are suited for high-flow pumping applications with low to moderate viscosity. Positive displacement pumps handle viscous fluids with precision.

2: Can a positive displacement pump run dry?

It is best to avoid letting a positive displacement pump run dry for an extended period of time. It can reduce the pump efficiency. In order to build a seal and generate the necessary hydraulic forces, the pumps require the presence of fluid. In addition to increasing friction, heat, and wear on components, running a positive displacement pump dry can also cause the seal to fail.

3: Are positive displacement pumps suitable for handling abrasive fluids?

Yes, these pumps are generally well-suited for handling abrasive fluids. Their design and operating principle make them suitable for transporting fluids containing solid particles or abrasive materials. To handle abrasive fluids, these pumps are designed to be robust and deliver non-impacting flow. 

4: How do I do maintenance of positive displacement pumps for common problems?

Check the power supply: Ensure that the pump is receiving proper electrical power or driver input.
Inspect for leaks: Examine the pump and associated piping for any signs of leaks, such as fluid dripping or spraying.
Monitor fluid levels: Low fluid levels can lead to poor performance or cavitation issues. Add fluid as needed, ensuring it is compatible with the pump and the application.