Kitchen Hood Suppression Calculator

Appliance nozzles are aimed directly at a cooking surface — a fryer's nozzle discharges into the vat, a grill's sweeps the cooking area — so the calculator counts one per fryer, grill/griddle section, and other appliance you enter, since UL 300 listings require dedicated coverage per appliance. The duct, by contrast, is a long enclosed volume rather than a hazard source, so it only needs a nozzle at the collar plus one more for every additional 20 feet of run to keep grease fire from spreading through the ductwork.

It multiplies your total nozzle count by roughly 1.5 gallons of wet chemical agent per nozzle, then matches that against the smallest standard tank size (1.5, 2.5, 3, 4, or 6 gallons) that can hold it. If the required agent volume exceeds even a single 6-gallon tank, the calculator switches to reporting multiple tanks (agent gallons divided by 6, rounded up) rather than assuming one oversized vessel exists.

The built-in wet-chemical system protects the hood, plenum, and appliances automatically, but NFPA 10 separately requires portable Class K extinguishers within 30 feet of travel distance for staff to fight a residual or reignited grease fire by hand. The calculator estimates this count from hood length divided by 30 feet, with a minimum of one extinguisher regardless of how short the hood is.

The low end is $3,000 base plus $500 per nozzle, and the high end is $6,000 base plus $1,000 per nozzle — a deliberately wide band meant to capture the spread between a basic single-manufacturer install and a more complex job with premium components or difficult access. It doesn't itemize labor rates, permit fees, or regional pricing differences, so treat it as an order-of-magnitude budgeting figure rather than a quote.