What is TFM?
TFM is chemically modified PTFE that fills the gap between conventional PTFE and melt-processable PFA. According to ASTM D 4894 and ISO Draft WDT 539-1.5, TFM is classified as a PTFE. Compared to conventional PTFE, TFM has the following enhanced properties: • Much lower deformation under pressure (cold flow) at room and elevated temperatures. • Lower permeability • May be used at higher pressures • On the subject of valve seats, explain cavity-filler seats and their use. Cavity-filler seats are intended to prevent the build up of materials that may when entrapped between the ball and body cavity- solidify or otherwise inhibit the smooth operation of the valve closure member. High Purity ball valves used in steam service should not utilize this optional seat arrangement as the steam will find its way under the seat surface and become an area for bacterial growth. Due to this larger seating area, cavity-filler seats are difficult to properly sanitize without disassembly. • What actuators
