**2103-440 PTFE S/T BUP FDA

Part number TST440 is an AS568-440 white PTFE (Teflon) 55 Shore D Back-Up Ring measuring an inside diameter of 6.725 in (170.82 mm), a cross section of 0.275 in (6.99 mm), and an outside diameter of 7.275 in (184.79 mm). A back-up ring extends o-ring service life by supporting the seal against extrusion under high pressure.

PTFE (Teflon) is valued for one of the lowest coefficients of friction of any solid and excellent dielectric properties. The material holds up against steam, strong acids and bases, and oxidizing media. Service temperature is rated from -65°F (-53.9°C) through 500°F (260°C). Exposure to service requiring elastic recovery or elemental fluorine at temperature will shorten service life.

Common environments for this compound include semiconductor fabrication, pharmaceutical and biotech, and laboratory equipment.

Reference part number TST440 when ordering; the item is sold individually. Nominal inside diameter is listed as 6 3/4 inch. Check the compound against your process media, pressure and temperature before committing to a design. If you need a size, durometer or compound that is not listed, APG can cross-reference from a print, a sample or a competitor part number.