Understanding Polyurethane Impellers

Maintain Maximum Pump Efficiency With The Right Impeller

Impellers are an essential component in the operation of many forms of machinery—both big and small. They can be found in various types of pumps, centrifugal compressors, wind turbines, jet skis, agitated tanks, and even consumer washing machines. Learn more about impellers, how they function within these different applications, and how PSI Urethanes can meet your custom polyurethane impeller needs.

What Is An Impeller?

An impeller is a rotor with vanes or blades that increases or decreases the pressure and flow of a fluid, typically within a piece of tubing.  The velocity gained by the fluid is transformed into pressure as the fluid leaves the pump. When used in wind turbines however, impellers are used to decrease pressure and airflow thus capturing the wind’s energy.  Impellers can be made out of a variety of materials, including iron, steel, brass, bronze, plastic, aluminum, and polyurethane.

How Does An Impeller Work?

When the impeller is made to rotate, it makes the fluid surrounding it rotate also.  This imparts centrifugal force to the fluid and moves it out radially.  In a pump, the fluid will enter the impeller through the eye(the middle), be pushed by the vanes and exit the pump through a tube, hose, or pipe.

During the process, rotational energy is transferred to the fluid. At the discharge side of the impeller, the kinetic energy and pressure of the fluid rises. On the suction side, fluid is displaced and there’s negative pressure at the eye of the impeller. This pressure helps suck fluid into the system, keeping the whole process going.

Types of Impellers

There are generally three categories of impellers.

Open Impellers: An open impeller has blades that are attached to a hub. This design looks very similar to a boat propeller or a fan.  They are ideal for situations in which the impeller needs to be cleaned on a regular basis or there is a risk of blockage. Though an open impeller tends to have low efficiency, its efficiency can be regularly maintained through impeller clearance adjustment.

Semi-Open Impellers: A semi-open impeller has a circular plate attached to one side of the blades. It is ideal for use with trash and debris laden liquids.

Closed Impellers: A closed impeller, also called a shrouded impeller, has one circular plate on each side. It ideal for pumping water and other liquids at higher head pressures. While the closed design is initially very efficient, it loses its efficiency as the wear ring clearance increases. The design of this impeller makes it more difficult to modify and because its internal parts are hidden, it’s hard to inspect for flaws.

Advantages of Polyurethane Impellers

Polyurethane is the preferred material for many impeller applications, especially highly abrasive and wear intensive applications. Polyurethane outperforms plastics, rubbers, and a number of metals in many ways, including:

  • Increased hardness range
  • Twice the tensile strength and tear strength as rubber
  • High energy absorption capability
  • Resistant to oil, chemicals, and environmental conditions
  • Extremely high abrasion resistance

Custom Polyurethane Impellers From PSI Urethanes

An impeller is one of the most important components of a pump’s performance. With a new or modified polyurethane impeller, you can give new life to an old pump. Call one of our experienced polyurethane professionals today at (800) 888-5156 to learn more about our precision cast polyurethane impellers. Or, conveniently request a quote for your custom polyurethane project online at any time.

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