Ordered as TST218, this is an AS568-218 white PTFE (Teflon) 55 Shore D Back-Up Ring measuring 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). The back-up ring allows a standard o-ring to operate at higher pressures than it could unsupported.
It resists steam, strong acids and bases, and nearly all industrial chemicals. PTFE (Teflon) delivers excellent dielectric properties and a very wide continuous service temperature range. Published continuous service range is -65°F (-53.9°C) to 500°F (260°C). Exposure to molten alkali metals or service requiring elastic recovery will shorten service life.
Typical settings include aggressive-media pipelines, pharmaceutical and biotech, and laboratory equipment.
Order part number TST218, sold individually. Nominal inside diameter is listed as 1 1/4 inch. Check the compound against your process media, pressure and temperature before committing to a design.
Description 2103-218 PTFE S/T BUP FDA
Actual Cross Section 0.139 inch (3.53 mm)
Actual Inside Diameter 1.234 inch (31.34 mm)
Actual Outside Diameter 1.512 inch (38.4 mm)
Measurement System Imperial
Product Category O-Rings - Backup Rings