# O-ring stretch and diameter selection
# Scope: Installed inner diameter circumferential stretch; thickness reduction omitted.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

freeDiameter = 20 mm
installedDiameter = 21 mm

stretch := (installedDiameter-freeDiameter)/freeDiameter

check example stretch budget: stretch <= 0.06

scenario alternative: freeDiameter = 16 mm