When corrosion resistance is an important factor in liquid transportation, centrifugal pumps made of special materials are an ideal choice. In this field, plastic centrifugal pumps (also referred to as plastic pumps for short) are used very successfully. Thanks to materials such as fiberglass, Teflon (PTFE), Tefzel (ETFE), Polypropylene (PP), and PVDF, these pumps exhibit high resistance to aggressive acids and other chemicals.

Pumps with plastic housings are often referred to as "plastic centrifugal pumps." Although such pumps exist, they are more suitable for individual use and are often found as low-cost garden or pool pumps sold in home improvement stores.

In contrast, industrial plastic pumps typically have a durable, metallic outer housing; however, their internal structures may be coated with plastic or consist entirely of plastic components. This design enhances both mechanical durability and chemical resistance, providing safe and long-lasting solutions for industrial applications.

How Does a Plastic Centrifugal Pump Work?

As the name suggests, a plastic centrifugal pump belongs to the group of centrifugal pumps and operates on the basis of radial pumps. Like all other centrifugal pumps, the liquid entering the pump housing is accelerated by the rotating impeller. In the volute casing outlet, the speed is converted to pressure. The impeller and volute casing must be compatible so that the hydraulic efficiency of the pump can be maximized.

The larger the impeller diameter and the rotational speed, the greater the pressure difference.

The wider the impeller and volute casing, the higher the pump's flow rate.

Like most pumps, plastic centrifugal pumps are powered by electric motors.

The pump's energy requirement increases in direct proportion to pressure and flow rate. The motor transfers energy from the pump shaft to the impeller, but not all of the energy is converted to pressure.

Some energy is lost due to friction in the bearings and hydraulic losses (such as backflow and vortex formation). Quality pump manufacturers develop high-efficiency designs by conducting R studies to minimize hydraulic losses.

Today, high-quality plastic pumps can achieve efficiency levels of up to 80%.

Plastic Pumps and Corrosion Resistance

Although plastic pumps are approached critically in many industries, they are used with great success in the chemical industries. These pumps are indispensable, especially in the field of fine and basic chemicals. Some aggressive chemicals where plastic centrifugal pumps have proven their durability include:

  • Hydrochloric acid (HCl)
  • Sulfuric acid (H₂SO₄)
  • Nitric acid (HNO₃)
  • Hydrofluoric acid (HF)
  • Phosphoric acid (H₃PO₄)
  • Fluorosilicic acid (H₂SiF₆)
  • Chlorine and chlorine-containing environments
  • Salt water and brine solutions

And many more aggressive chemicals.

Plastic centrifugal pumps can be manufactured from materials such as PFA, PP (polypropylene), or PVDF (polyvinylidene fluoride) and can be used in a wide flow range from a few liters to thousands of cubic meters. While standard solutions are widely available for small volume pumps (up to 1 m³/h), manufacturers must meet special designs and extensive documentation requirements for large-scale industrial pumps.

For applications with very low flow rates or dosing systems, positive displacement pumps (e.g., diaphragm pumps) are the best solution. However, the most common solution that meets a wide flow range is centrifugal pumps. Although the design and operating principles are different, all components in contact with the medium are made of plastic.

Standards That Plastic Centrifugal Pumps Must Meet

Pumps used in industrial processes must comply with certain regulations and standards in terms of safety and performance. Companies that manufacture plastic centrifugal pumps are subject to the same safety rules as metal pumps. These rules are aimed both at preventing damage to the pumps and at preventing the leakage of environmentally harmful or toxic substances. The important regulations that must be followed are:

  • EU Machinery Directive
  • ATEX Directive (for explosive atmospheres)
  • ISO 5199 (Design standards for industrial process pumps)
  • ISO 2858 (Size and performance criteria for centrifugal pumps)

Safety Precautions for Plastic Pumps

A practical safety solution for plastic pumps is the magnet-coupled pump design. In this design:

✔ Internal components are made entirely of plastic or silicon carbide ceramic.

✔ The outer housing is made of cast iron, which provides pressure resistance and protects against external influences.

✔ Thanks to the magnetic coupling, it is completely isolated from the liquid medium and the risk of leakage to the environment is eliminated.

However, mechanical seal models are also sufficient for some applications. Both systems can be preferred according to the area of use.

As a result, plastic centrifugal pumps offer an excellent solution in applications requiring chemical resistance and are manufactured in accordance with safety standards.

Material Types for Plastic Pumps

Four main factors should be considered when selecting materials for plastic pumps:

  • Chemical resistance
  • Abrasion resistance
  • Temperature resistance
  • Material availability

The most durable plastics used for centrifugal pumps are thermoplastics such as UHMW-PE (ultra-high molecular weight polyethylene), PTFE (Teflon), ETFE (Tefzel), and PFA (perfluoroalkoxy polymer).

Like metal pumps, plastic pumps must be manufactured from materials compatible with the operating conditions and pump characteristics. However, economic factors should also be taken into account. For example, just as metal pumps do not always require expensive alloys (e.g., Hastelloy), plastic pumps do not always need to be made of high-cost PFA. Fiberglass or PVDF (polyvinylidene fluoride) materials are sufficient for many applications.

If the operating temperature, pump capacity, and pressure requirements are at appropriate levels, plastic pumps can offer corrosion-resistant solutions. They can transport a wide range of chemicals, from salt water to aggressive inorganic acids and basic liquids.

You can contact us for more information or technical support about plastic centrifugal pumps.