: Typically involves a soft vs. hard combination, such as carbon graphite versus silicon carbide or tungsten carbide, depending on fluid viscosity and abrasiveness.

often summarize the core principles, including fluid leakage prevention and system integrity. Industry Design Guides : For practical application, the Apple Rubber Seal Design Guide

: Uses constant contact between a rotating seal face (primary ring) and a stationary seal face (mating ring) to prevent fluid leakage.