The FKM (Fluoroelastomer) sealing element is recommended for applications such as solar, district heating, low-pressure steam, various chemicals and compressed air systems. Viega press fittings with white dots indicate an FKM sealing element. It has an operating temperature from 14ºF to 284ºF (-10ºC to 140ºC) with the capacity to withstand heat spikes up to 356ºF (180ºC).
All Viega ProPress fittings are designed with cylindrical pipe guides to keep the pipe straight and protect the sealing element during assembly. Fittings that do not have cylindrical pipe guides risk making an unsecure connection. Without the pipe guides, installers can damage the sealing element. Viega fittings are pressed before, after and on top of the sealing element in a single step, which creates a permanent, secure connection.