2103-391 PTFE S/T BUP FDA

This back-up ring is supplied in AS568-391 white PTFE (Teflon) 55 Shore D supplied with an inside diameter of 21.953 in (557.61 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 22.373 in (568.27 mm), catalogued under part number TST391. It bridges the extrusion gap so the primary seal holds its shape under load.

PTFE (Teflon) is specified here for very wide continuous service temperature range and non-stick, non-contaminating surface characteristics. It resists steam, solvents, and oxidizing media. The material carries a published service range of -65°F (-53.9°C) to 500°F (260°C).

It sees regular use in semiconductor fabrication, laboratory equipment, and pharmaceutical and biotech.

Stocked as TST391 and sold individually. As always, verify media compatibility and operating conditions against the requirements of your specific application. APG can cross-reference from an existing part number, a drawing or a physical sample if this size is not an exact match.