**2107-250 PTFE SPIRAL B/U FDA

APG stocks the TSP250, an AS568-250 white PTFE (Teflon) 55 Shore D Back-Up Ring with an inside diameter of 4.984 in (126.59 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 5.262 in (133.65 mm). A back-up ring installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

The material holds up against strong acids and bases, oxidizing media, and nearly all industrial chemicals. PTFE (Teflon) is valued for one of the lowest coefficients of friction of any solid and near-universal chemical inertness. The material carries a published service range of -65°F (-53.9°C) to 500°F (260°C). Applications involving molten alkali metals or service requiring elastic recovery call for a different compound.

It sees regular use in chemical processing, pharmaceutical and biotech, and aggressive-media pipelines.

This item is sold individually under part number TSP250. Nominal inside diameter is listed as 5 inch. Check the compound against your process media, pressure and temperature before committing to a design. APG supports cross-referencing from drawings, samples and competitor numbers when a listed size is not an exact fit.