Thermoplastic valves have become more and more popular for certain applications and media. The search for alternative valve materials raises the need for a careful evaluation of the many benefits that plastics can provide, as well as some of the limitations which make it unsuitable in some instances.
Plastic valves have been around for only several decades. So, it’s relatively new compared to the metal valve industry, which most probably originated in ancient Rome. Those early bronze valves were key in the construction and development of the Roman canal systems that were far ahead of their time. Still, despite the short history of plastic valves, they’ve come a long way.
As with their metallic counterparts, not all plastic materials are equal. They come in various grades and are more or less suited to different applications. The most common thermoplastic material used today is PVC (polyvinyl chloride). PureValve PVC valves are rated for pressures of up to 150 psi at 25ºC. Maximum safe operating temperature is 60ºC, though pressure ratings will have fallen with the increase in heat. A derviation of PVC, chrolinated PVC (c-PVC) can handle temperatures up to 80ºC.
Other materials developed to meet higher temperature and pressure requirements include PVDF (polytetrafluoroethylene). PVDF valves can be designed to meet pressure ratings up to 230 psi and can safely manage temperatures of up to 150ºC.
Thermoplastic valves often provide a significant cost advantage when compared to traditional metal alloy valves. They are lightweight which reduces shipping costs, as well as facilitating installation and maintenance – something maintenance staff in any plant will appreciate. For some critical applications, like the manufacturing of corrosive chemicals or semiconductors, the thermoplastic valves reach excellent reliability. This is the niche that thermoplastics shine in.