APG stocks the TST241, an AS568-241 white PTFE (Teflon) 55 Shore D Back-Up Ring built to an inside diameter of 3.859 in (98.02 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 4.137 in (105.08 mm). A back-up ring allows a standard o-ring to operate at higher pressures than it could unsupported.
The material holds up against solvents, steam, and strong acids and bases. PTFE (Teflon) is known for one of the lowest coefficients of friction of any solid and non-stick, non-contaminating surface characteristics. Service temperature is rated from -65°F (-53.9°C) through 500°F (260°C). Applications involving service requiring elastic recovery or molten alkali metals call for a different compound.
Typical settings include food and beverage, semiconductor fabrication, and chemical processing.
Reference part number TST241 when ordering; the item is sold individually. Nominal inside diameter is listed as 3 7/8 inch. Application requirements vary, so validate compatibility with your process conditions prior to installation. For a size or compound outside the standard catalog, APG can quote from a print or sample.
description 2103-241 PTFE S/T BUP FDA
Actual_CS 0.139 inch (3.53 mm)
Actual_ID 3.859 inch (98.02 mm)
Actual_OD 4.137 inch (105.08 mm)
ProductCode Description O-Rings - Backup Rings