The TST204 is an AS568-204 white PTFE (Teflon) 55 Shore D Back-Up Ring with an inside diameter of 0.359 in (9.12 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 0.637 in (16.18 mm). This back-up ring installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.
The compound resists oxidizing media, strong acids and bases, and nearly all industrial chemicals. PTFE (Teflon) is widely chosen for excellent dielectric properties and non-stick, non-contaminating surface characteristics. The material carries a published service range of -65°F (-53.9°C) to 500°F (260°C).
You will find this material specified across pharmaceutical and biotech, semiconductor fabrication, and aggressive-media pipelines.
Order part number TST204, sold individually. As always, verify media compatibility and operating conditions against the requirements of your specific application.
Description 2103-204 PTFE S/T BUP FDA
Actual Cross Section 0.139 inch (3.53 mm)
Actual Inside Diameter 0.359 inch (9.12 mm)
Actual Outside Diameter 0.637 inch (16.18 )
Measurement System Imperial
Product Category O-Rings - Backup Rings