Fire Suppression
Hood Duct Suppression Length
Duct nozzles are listed for a max perimeter and length per nozzle. Plug in your duct size to see how many you need.
⚠ Listed nozzle limits are the design authority
Ansul R-102 1N nozzle: max 50" perimeter, max 12 ft length. Different nozzles have different limits. Always reference the actual manufacturer's listing for your system.
FAQ
Where do duct nozzles go? +
First nozzle within the duct collar inside the hood, typically pointing up into the duct. Additional nozzles every 12 ft (for 1N) along long horizontal runs and at every elbow.
What if duct is too big for one nozzle type? +
Use the next size up (2W or 3N) or add nozzles in pairs at strategic locations. Always per the manufacturer's listed design.
Vertical vs horizontal duct runs? +
Vertical runs are typically protected by one nozzle at the bottom. Horizontal runs may need multiple based on length and elbows.