Fire Protection in Aircraft Hangars: Group I vs. Group II

Aircraft hangars pose a unique challenge when it comes to fire protection. Depending on the size of the hangar and the materials used to build the structure, hangars are categorized into one of 4 groups. These 4 groups all have different requirements for fire protection. Groups I & II are mostly similar when it comes to fire protection system requirements. However, they do have a few main differences:

• Group I hangars require draft curtains to enclose projected floor areas of 7,500 ft2 or less
• Group I requires 0.17 gpm/ft2 over 15,000 ft2 when closed-head sprinkler systems are chosen
• Group II requires 0.17 gpm/ft2 over 5,000 ft2 when closed-head sprinkler systems are chosen
• Water flow duration times are approximately 50% longer for Group I hangar fire suppression systems than those for Group II
• Group II hangars are not required to implement draft curtains