Antifreeze is used in fire sprinkler systems in spaces subject to freezing where the temperature cannot reliably be maintained at or above which temperature?

• A. Below 32°F
• B. Below 28°F
• C. Above 40°F
• D. Above 60°F

Answer: (C)

Antifreeze is used in sprinkler systems in areas that can freeze when you cannot keep the space at or above a certain temperature. That temperature is 40°F. If the space cannot reliably be maintained at or above 40°F, antifreeze is required to prevent the water in the piping from freezing. The other temperatures aren’t the standard threshold for this requirement: 32°F is the freezing point of water, but the protection rule uses 40°F; 60°F is well above freezing and doesn’t trigger antifreeze; 28°F is well below freezing and not the decision point used. So the idea is to use antifreeze when you can’t keep the area at least at 40°F.