8-438 FLUOROELASTOMER 90 B/U RING

This FKM Viton 90A Backup Ring, item VBU90438, is designed for buyers who need a clear specification match for anti-extrusion support behind O-rings in high-pressure hydraulic and pneumatic glands. The item is specified by AS568-438; 6.225 inch (158.12 mm) ID x 0.275 inch (6.99 mm) CS; 6.775 inch (172.09 mm) OD, with 6 1/4 inch nominal ID; 1/4 inch nominal CS for cross-reference against common gland and replacement dimensions. Its FKM/Viton fluoroelastomer material provides high-temperature service, fuels, lubricants and many chemical sealing environments. It is with a listed temperature range of -15°F (-26°C) to 400°F (204°C), which can help narrow material selection for heat, cold or process exposure. The black color and round profile provide a practical visual identifier during receiving, stocking and installation. As a backup ring, it works with a primary O-ring to help limit extrusion into clearance gaps under pressure. The each-unit format supports precise replacement, kitting, resale and job-specific purchasing. Common purchasing identifiers for this product include the material name, O-ring type, dimensional size, hardness and intended sealing application. Those attributes make the item easier to compare for maintenance, OEM production, MRO replacement and reseller catalog use.