Flame Ignition Limits: Ignitable Gas Envelope Considerations

The ignitable gas envelope is importantto establishing separation distances forunintended releases of hydrogen.

• The extent of the ignitable gas envelopecan be based on several criteria. Which is best for Codes & Standardsdevelopment?
• For example:
  • Time-averaged H2concentrationfield  reveals extent of cloud withintraditional flammability limits (4% LFLto 75% RFL).
  • Do traditional (static) flammabilitylimits   provide a suitable measure ofignitability in turbulent flowingsystems?