A grease hood is a fire-safety system, and two obligations come with it: an automatic fire-suppression system over the appliances and regular NFPA 96 cleaning of the hood, filters, and duct. Neglect either and you risk a grease fire, a failed inspection, or a voided insurance claim. These answers cover how suppression systems like Ansul work, when they are required, inspection intervals, and how often and by whom the exhaust system must be cleaned. Your fire-suppression contractor and AHJ set the specifics.
Ansul is a well-known brand of restaurant fire-suppression system, and the name is often used generically for any kitchen hood suppression system. It is an automatic wet-chemical system with nozzles aimed at the cooking appliances, plenum, and duct that discharges when a fire is detected, smothering grease fires and shutting off fuel. Learn how these systems work in our fire suppression guide.
Yes. Ansul is a manufacturer of automatic fire-suppression systems, most familiar as the wet-chemical systems installed over commercial cooking lines. Because the brand is so common, people often say Ansul when they mean any kitchen hood suppression system. Other brands exist and work on the same principles. All modern versions must meet the UL 300 standard for restaurant cooking suppression.
Detection links (fusible or electronic) sense a fire's heat and trigger the system. It discharges wet chemical through nozzles onto the appliances, hood plenum, and duct, forming a soap-like blanket that smothers the flames and cools the grease. At the same time it shuts off gas or electric power to the equipment and can trip building alarms. Read the sequence in our fire suppression guide.
They activate automatically when a detection link in the hood senses fire-level heat, releasing the wet chemical. They can also be triggered manually by a pull station, which staff should know how to use. On discharge, the system shuts off fuel to the appliances. Automatic and manual activation are both required features of a compliant kitchen suppression system, verified during inspection.
Yes. A compliant kitchen suppression system discharges automatically when its detectors sense a fire, without anyone present. It also includes a manual pull station as a backup so staff can trigger it deliberately. This automatic response is the whole point: grease fires spread fast, and the system must act instantly, day or night, whether or not the kitchen is staffed.
Yes. Every compliant kitchen fire-suppression system has a manual pull station, usually located along the path of egress, that lets staff discharge the system immediately if they see a fire before the automatic detectors trigger. Employees should be trained on where it is and how to use it. Manual activation supplements, but does not replace, the automatic detection.
Effectively yes. A listed automatic fire-suppression system is required over commercial cooking appliances that produce grease-laden vapor under a Type I hood. Because grease fires are fast and intense, code and insurers treat suppression as mandatory for grease cooking. Type II heat-and-steam hoods do not require it. Confirm the specifics against the general requirements overview and with your AHJ and fire-suppression contractor.
For Type I grease hoods, yes, an automatic system meeting UL 300 is required over the cooking appliances. It is a core fire-safety and code requirement, and insurers generally will not cover a grease kitchen without one. Type II hoods over dishwashers or steamers do not need suppression because there is no grease. Your fire-suppression contractor and AHJ confirm the requirement for your equipment.
No. Type II hoods handle only heat, steam, and moisture with no grease, so they do not require a fire-suppression system. Suppression is tied to grease-laden cooking under Type I hoods. If any grease-producing equipment is present, though, you need a Type I hood with suppression instead. Confirm your hood classification with your engineer so nothing that makes grease is left unprotected.
UL 300 is the safety standard that modern restaurant fire-suppression systems must meet. It was adopted after high-efficiency fryers and vegetable oils made older dry-chemical systems inadequate; UL 300 systems use wet chemical designed to smother today's hotter grease fires and cool the oil, as our fire suppression guide covers. A pre-UL 300 system is likely non-compliant and should be upgraded.
A wet-chemical system, the UL 300 standard for kitchens, discharges a liquid agent that reacts with hot grease to form a thick, soap-like foam. That blanket smothers the fire and cools the oil to prevent reignition, which dry-chemical systems struggled to do with modern high-temperature cooking oils. Wet chemical is now the required type over commercial cooking lines. After any discharge the system must be professionally recharged.
Kitchen suppression systems require professional inspection and service on a regular interval, commonly about every six months, by a licensed fire-protection company, plus checks after any discharge. During service the technician verifies detection links, nozzles, agent, and the fuel shutoff, as our fire suppression guide describes. Your local fire code and AHJ set the exact interval; keep the tags, since inspectors and insurers ask for them.
Typically about twice a year by a certified fire-suppression contractor, who inspects and tests the system, replaces fusible links as needed, and confirms it will actuate and shut off fuel. Service is also required after any discharge to recharge and reset it. Because intervals are set by local code and the manufacturer, follow your AHJ's schedule and keep the service tags current for inspections and insurance.
Many jurisdictions require the kitchen suppression system to be tied into the building fire-alarm system so that a discharge signals an alarm and, where required, notifies a monitoring service or the fire department. Whether monitoring is mandatory depends on local code and building type. Your fire-suppression contractor and AHJ will tell you what integration and monitoring your kitchen requires.
It discharges wet chemical over the appliances, hood, and duct, shuts off gas or electric power to the cooking line, and typically trips the building alarm. Cooking stops immediately, and the kitchen is out of service until a licensed contractor recharges and resets the system and the mess is cleaned. All food exposed to the chemical must be discarded. Plan for downtime after any activation.
Ensure everyone is safe and the fire is out, evacuate if needed, and confirm fuel to the appliances has shut off. Do not attempt to cook or reset it yourself. Discard any exposed food, ventilate, and call your licensed fire-suppression company to inspect, recharge, and reset the system before reopening. Also notify your AHJ or fire department if local rules require it after any discharge.
You do not reset it yourself. After any discharge the system must be inspected, recharged with new agent, have fusible links replaced, and be reset and retagged by a licensed fire-suppression contractor before the kitchen can operate again. Attempting a DIY reset leaves the kitchen unprotected and non-compliant. Call your service company promptly, since the appliances stay locked out until the system is restored.
A new kitchen suppression system is a meaningful installed cost that scales with the number of appliances and nozzles, the fuel shutoffs, and alarm integration, and semiannual service and recharges after a discharge add ongoing cost. Because size and local labor vary widely, get quotes from licensed fire-suppression companies rather than budgeting from a single figure. Factor in the recurring inspection cost too.
Installation depends on how many appliances and nozzles are covered, the gas or electric shutoff work, alarm tie-ins, and permits, so it varies substantially by kitchen and region. It is usually installed alongside the hood by a licensed fire-protection contractor. Get itemized bids, and remember the total cost of ownership includes semiannual inspections and recharging the system after any discharge.
They are commonly integrated so that a discharge trips the building fire alarm and, where required, notifies a monitoring service. The system itself focuses on detection and suppression; the audible or visual alarm and any off-site notification come from the tie-in to the building's alarm panel. Whether that integration is mandatory depends on local code, which your suppression contractor and AHJ will specify.
On discharge, the system automatically shuts off the energy source to the protected appliances, closing a gas valve or tripping electric power, so the fire is not being fed fuel while it is suppressed. This interlock is a required part of the design and is verified at each inspection. The wiring and gas valve work are coordinated between the suppression installer, electrician, and hood contractor.
NFPA 96 sets cleaning frequency by cooking volume: high-volume or solid-fuel operations may need monthly service, moderate-volume kitchens roughly quarterly, and low-volume operations semiannually or annually. This is professional cleaning of the hood, filters, plenum, duct, and fan, separate from daily wipe-downs. Track your interval and keep records. Our NFPA 96 hood cleaning guide explains the categories.
Grease baffle filters should be cleaned frequently, often nightly or every few days depending on cooking volume, because grease-loaded filters cut airflow and feed fires. This routine filter cleaning is a daily-operations task, separate from the periodic professional cleaning of the full hood, duct, and fan required by NFPA 96. Keeping filters clean is one of the simplest ways to reduce grease-fire risk.
Grease builds up on filters, in the hood plenum, throughout the duct, and at the fan, and that grease is fuel: a spark or flare-up can ignite it and send fire through the duct into the building. NFPA 96 requires periodic professional cleaning of the whole exhaust path to remove that fuel. It is a fire-safety and insurance requirement, not just housekeeping, as our cleaning guide explains.
Professional NFPA 96 cleaning is priced by the size and complexity of the system, the length and access of the duct run, and the level of grease, so quotes vary widely. High-volume kitchens that need frequent service pay more over a year. Get bids from certified hood-cleaning companies experienced with NFPA 96, and keep the service stickers, since inspectors and insurers require proof.
A typical professional cleaning of the hood, filters, plenum, duct, and fan takes a few hours, though heavily grease-laden or hard-to-access systems take longer. It is usually done after hours so the crew can shut down and cover the line, degrease, and restore everything before service. Ask your cleaning company for a time estimate based on your system's size and grease level.
Remove the baffle filters and soak them in hot water with a degreaser, or run them through a commercial dishwasher if the manufacturer allows, then rinse and dry before reinstalling. Do this on a regular schedule, often nightly, so grease does not accumulate. This handles the filters only; the hood plenum, duct, and fan still require periodic professional NFPA 96 cleaning.
Metal grease baffle filters can usually be cleaned in a commercial dishwasher, which is a convenient way to degrease them on a regular schedule; check the manufacturer's guidance first. Wash them separately from dishware to avoid transferring grease. Dishwasher cleaning covers the filters only, not the hood interior, duct, or fan, which still need periodic professional cleaning under NFPA 96.
Daily, wipe down surfaces and clean the baffle filters. Periodically, a certified crew degreases the full system, hood interior, plenum, duct, and exhaust fan, back to bare metal, on the NFPA 96 schedule for your cooking volume. Interior duct and fan cleaning is specialized work that requires access panels and proper chemicals, so leave the deep NFPA 96 cleaning to professionals and keep their service records for inspection.
Daily filter and surface cleaning is done by staff, but the periodic NFPA 96 cleaning of the hood interior, duct, and fan should be performed by a certified hood-cleaning company that documents the work with dated service stickers and a report. Inspectors and insurers expect that documentation. Using a qualified, insured contractor also ensures the hard-to-reach duct and fan are actually cleaned to standard.
Commercial kitchen exhaust cleaning, or hood cleaning, is the periodic professional degreasing of the entire exhaust path, filters, hood plenum, duct, and exhaust fan, down to bare metal, to remove the grease that fuels duct fires. It is required by NFPA 96 at intervals based on cooking volume and is documented for inspectors and insurers. Our NFPA 96 cleaning guide covers the standard in detail.
Testing is performed by a licensed fire-suppression technician during scheduled service. They inspect and verify detection links, nozzle placement and caps, agent level and pressure, and the fuel shutoff and alarm interlocks, confirming the system will actuate correctly, typically without a full discharge. Staff should not test it themselves. Keep the current inspection tag visible; it is proof the system was verified.