The ID and OD of an O-ring gland is primarily influenced by the diameter of the mating surface. Although the cross-section of the O-ring is seen as fairly arbitrary, there are some distinct advantages to either a larger or smaller cross-section O-ring. Listed below are the advantages for each:

 

 

Advantages of a Smaller Cross-Section

 

★More compact

★Lighter weight

★Less expensive; especially for higher cost elastomers like FKM or fluorosilicone

★Less machining required for machined grooves since grooves are smaller

★More resistant to explosive decompression

 

 

Advantages of Larger Cross-Section

 

☆ Less prone to compression set

☆ Less volume swell in liquid on a percentage basis

☆ Allows for larger tolerance while still maintaining acceptable compression squeeze and compression ratio over full stack-up range

☆ Less prone to leakage due to contamination; dirt, lint, scratches, etc.