The most obvious limitation of thermoplastic Plastic Pump(KEXON) concerns the operating temperatures they can accommodate. Although a few thermoplastics, particularly the fluoropolymers, can retain their properties at temperatures as high as 550°F, commercially available thermoplastic pumps are generally not recommended for continuous service above 275°F. At higher temperatures, loss of mechanical properties and stress-cracking corrosion may hinder performance. In practice, this is not a widely relevant disadvantage, because corrosive fluids are generally handled at moderate temperatures. Pumps that employ flexible liners incur an additional temperature limitation on the liner material. For instance, although a fluoropolymer casing or body block may be suitable for high temperatures as indicated above, the upper limit of the elastomeric materials is usually about 275°F.

As regards capacity, the upper limit for thermoplastic centrifugal pumps on the market today is about 1,000 gal/min, with heads to 240ft. The largest rotary pumps cannot exceed 40 gal/min. The largest thermoplastic magnetic-drive chemical pumps are limited to approximately 400 gal/min against a total dynamic head of 40 ft. Impact resistance and strength of thermoplastic pumps may also pose a problem. They must be protected against falling objects and similar impact dangers, because of possible deformation if the operating temperature is high. Furthermore, thermoplastic material tends to elongate under sustained load (creep) as temperatures rise. For these reasons, thermoplastic pumps must generally be armored, by surrounding the plastic with a metal sheath. This is particularly true of horizontal centrifugal pumps that are exposed in normal plant operations. Accordingly, these plastics' light weight cannot be considered an advantage in those pumps.

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