2103-309 PTFE S/T BUP FDA

TST309 is an AS568-309 white PTFE (Teflon) 55 Shore D Back-Up Ring built to an inside diameter of 0.412 in (10.46 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 0.832 in (21.13 mm). In service, this back-up ring installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

PTFE (Teflon) offers near-universal chemical inertness and one of the lowest coefficients of friction of any solid. The material holds up against steam, strong acids and bases, and solvents. The material carries a published service range of -65°F (-53.9°C) to 500°F (260°C). It should not be specified for service in molten alkali metals or service requiring elastic recovery.

It sees regular use in aggressive-media pipelines, semiconductor fabrication, and laboratory equipment.

This item is sold individually under part number TST309. Nominal inside diameter is listed as 7/16 inch. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing. APG can cross-reference from an existing part number, a drawing or a physical sample if this size is not an exact match.