Ordered as TST344, this is an AS568-344 white PTFE (Teflon) 55 Shore D Back-Up Ring measuring an inside diameter of 3.85 in (97.79 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 4.27 in (108.46 mm). The back-up ring bridges the extrusion gap so the primary seal holds its shape under load.
As a material, PTFE (Teflon) is known for a very wide continuous service temperature range and non-stick, non-contaminating surface characteristics. Expect good resistance to oxidizing media, nearly all industrial chemicals, and solvents. Continuous operating temperature is published at -65°F (-53.9°C) to 500°F (260°C). Verify compatibility before use with molten alkali metals or elemental fluorine at temperature.
Common environments for this compound include semiconductor fabrication, laboratory equipment, and aggressive-media pipelines.
This item is sold individually under part number TST344. Nominal inside diameter is listed as 3 7/8 inch. As always, verify media compatibility and operating conditions against the requirements of your specific application. APG supports cross-referencing from drawings, samples and competitor numbers when a listed size is not an exact fit.
description 2103-344 PTFE S/T BUP FDA
Actual_CS 0.21 inch (5.33 mm)
Actual_ID 3.85 inch (97.79 mm)
Actual_OD 4.27 inch (108.46 mm)
ProductCode Description O-Rings - Backup Rings