APG stocks the VBU90004, an AS568-004 black Viton® (FKM) 90 Shore A Back-Up Ring with an inside diameter of 0.07 in (1.78 mm), a cross section of 0.07 in (1.78 mm), and an outside diameter of 0.21 in (5.33 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.
Viton® (FKM) is specified for very low compression set at elevated temperature and outstanding high-temperature capability. The material holds up against aromatic hydrocarbons, aggressive chemicals, and many acids. Published continuous service range is -15°F (-26.1°C) to 400°F (204.4°C).
Typical settings include aerospace, oil and gas, and chemical processing.
VBU90004 ships individually. Nominal inside diameter is listed as 5/64 inch. Check the compound against your process media, pressure and temperature before committing to a design. APG can cross-reference from an existing part number, a drawing or a physical sample if this size is not an exact match.
Description 8-004 BLACK FKM 90D BACK-UP RING
Actual Cross Section 0.07 inch (1.78 mm)
Actual Inside Diameter 0.07 inch (1.78 mm)
Actual Outside Diameter 0.21 inch (5.33 mm)
Measurement System Imperial
Product Category O-Rings - Backup Rings