Natural gas is lighter than air, and will rise and disperse within a facility. Garage upgrades are designed to detect a potential hazard, dilute the gas to reduce ignition risk, and then extract the gas for safe re-entry.
Alarm System Demonstration
Participants at Gas Technology Institute’s Alternative Fuel Vehicle Maintenance Garage Workshop had the opportunity to see a demonstration of a two-level alarm system installed in a CNG and LNG maintenance garage just outside of Chicago. The requirement is for the alarm system to activate at 25% of the Lower Flammability Limit (LFL) of natural gas in air. To avoid false alarms and unnecessary evacuations, a best practice is to activate warning lights, a mild alarm, and ventilation at 20% of the LFL, and then a more extreme evacuation alarm along with hazard lights, strobe lights, and continued ventilation if 40% of LFL is reached. For more information on gas detection and alarm systems, see the best practices or the code reports.