Busch O-Ring, 61.9 x 3.53 mm – Viton Part# 320274

This O-ring has a 61.9 mm inner diameter and a 3.53 mm cross-section . That means the rubber ring itself is 3.53 mm thick.

The 3.53 mm thickness is a standard AS568 size (often called a “-2xx” series dash number). It is a very common industrial size. The 61.9 mm inner diameter makes this a mid-size O-ring, used in many pump applications.

Viton is a brand name for a type of synthetic rubber. The technical name is FKM (Fluoroelastomer). Viton is special because it can handle things that destroy regular rubber :

• High temperatures – Works from -25°C up to +200°C (some grades up to +230°C) 

• Harsh chemicals – Oils, fuels, acids, aliphatic and aromatic hydrocarbons, and some fire-resistant oils 

• Vacuum pressure – It holds its shape even under strong vacuum