339 PTFE SOLID BACKUP RING FDA

APG stocks the TST339SO, an AS568-339 white PTFE (Teflon) 55 Shore D Back-Up Ring with an inside diameter of 3.225 in (81.92 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 3.645 in (92.58 mm). A back-up ring allows a standard o-ring to operate at higher pressures than it could unsupported.

As a material, PTFE (Teflon) offers excellent dielectric properties and near-universal chemical inertness. It resists strong acids and bases, steam, and solvents. Continuous operating temperature is published at -65°F (-53.9°C) to 500°F (260°C). Applications involving service requiring elastic recovery or molten alkali metals call for a different compound.

It sees regular use in aggressive-media pipelines, pharmaceutical and biotech, and laboratory equipment.

Stocked as TST339SO and sold individually. Nominal inside diameter is listed as 3 1/4 inch. Check the compound against your process media, pressure and temperature before committing to a design.