218 PTFE SOLID BACKUP RING FDA

APG stocks the TST218SO, an AS568-218 white PTFE (Teflon) 55 Shore D Back-Up Ring supplied with an inside diameter of 1.234 in (31.34 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 1.512 in (38.4 mm). A back-up ring extends o-ring service life by supporting the seal against extrusion under high pressure.

PTFE (Teflon) is known for one of the lowest coefficients of friction of any solid and a very wide continuous service temperature range. It resists solvents, nearly all industrial chemicals, and steam. The material carries a published service range of -65°F (-53.9°C) to 500°F (260°C). Applications involving elemental fluorine at temperature or molten alkali metals call for a different compound.

It sees regular use in laboratory equipment, chemical processing, and aggressive-media pipelines.

This item is sold individually under part number TST218SO. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing. 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.