APG stocks the TSP236, an AS568-236 white PTFE (Teflon) 55 Shore D Back-Up Ring supplied with an inside diameter of 3.234 in (82.14 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 3.512 in (89.2 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.
PTFE (Teflon) is widely chosen for near-universal chemical inertness and one of the lowest coefficients of friction of any solid. It resists solvents, oxidizing media, and nearly all industrial chemicals. Rated temperature range runs from -65°F (-53.9°C) to 500°F (260°C) in continuous service.
It sees regular use in chemical processing, pharmaceutical and biotech, and laboratory equipment.
Reference part number TSP236 when ordering; the item is sold individually. Nominal inside diameter is listed as 3 1/4 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 *2107-236 PTFE SPIRAL B/U FDA
Actual_CS 0.139 inch (3.53 mm)
Actual_ID 3.234 inch (82.14 mm)
Actual_OD 3.512 inch (89.2 mm)
ProductCode Description O-Rings - Backup Rings