How often does an Ansul system need to be inspected?

A certified company must service it at least every 6 months, after any discharge, and — according to Ansul — after a major hood and duct cleaning. The owner should also inspect it visually every month. Agent cylinders and hoses need a hydrostatic test every 12 years.

What does the owner check every month?

That appliances are in their protected positions, the manual pull station is visible and unobstructed, the service tag is in date, any pressure gauges read in range, and the nozzle blow-off caps are in place. NFPA 17A requires a monthly inspection following the manufacturer’s directions.

How often are fusible links replaced?

It depends on the state. Minnesota’s fire marshal requires at least annually; Utah’s code requires semiannually or at the manufacturer’s interval, with each link stamped with its installation year.

What happens after an Ansul system discharges?

Call the authorised distributor to recharge it and find the cause; the kitchen is unprotected until then. Ansul says to clean up within 24 hours with warm water and detergent.

Do I need a K-class extinguisher if I have an Ansul system?

Yes. Minnesota, for example, requires a Class K portable extinguisher within 30 feet of cooking appliances using oils and fats. It complements the fixed system rather than replacing it.

Is the Ansul inspection the same as hood cleaning?

No. They are separate services on separate schedules. Ansul asks for the suppression system to be serviced after a major hood and duct cleaning.

Hoods · Fire suppression

Ansul system inspection

Q: What is a UL 300 system?

A kitchen fire suppression system listed to UL 300, the fire test standard for systems protecting commercial cooking equipment. NFPA 17A requires it, and Minnesota’s fire marshal refers to kitchen systems simply as UL 300 systems.

The wet-chemical fire suppression system over a cooking line — usually called an Ansul system after the best-known brand — has two inspection schedules, not one. A certified company services it every six months. The owner is supposed to check it every month, and most never do.

Last reviewed November 2026

The short answer

What	Who	How often
Visual inspection	The owner or staff	Monthly
Full maintenance and service	A certified fire protection company — an authorised distributor for Ansul systems	Every 6 months, and after any discharge
Fusible links (heat detectors)	The service company	Annually or semiannually, depending on your state
Hydrostatic test of the agent cylinders and hoses	The service company	Every 12 years

NFPA 17A, the standard for wet-chemical systems, sets the monthly, semiannual and 12-year intervals. Ansul's own owner's guide says the same: maintenance "must be performed semi-annually," by an authorised distributor, and the system "should be inspected at least monthly."

The 6-monthly service

Ansul's guide asks for service at a maximum of 6-month intervals and immediately after major hood and duct cleaning, because cleaning crews work around nozzles and detection lines. Several fire codes, including Minnesota's, also require service after any activation.

California's semi-annual inspection form for wet-chemical systems shows what the technician works through, item by item:

Manual pull stations unobstructed, and automatic detection and manual activation both working.
The fuel shut-off operating correctly — the gas valve or electrical cut-off that kills the cooking appliances when the system fires.
Nozzles correct, clean and aimed properly, with blow-off caps in place and undamaged.
The agent cylinder free of corrosion, cartridge weights within limits, and containers within their hydrostatic test dates.
Fusible links and other heat detectors maintained or replaced.
Hoods, ducts and filters in place and clean.
Whether any protected cooking appliance has been replaced, modified or moved.

When it's done, the system gets a new dated service tag. A fire inspector checks that tag; Utah's code says a non-compliance tag doesn't meet the requirement.

The monthly check the owner is responsible for

NFPA 17A calls for an inspection at least monthly, following the manufacturer's directions. Koorsen's summary of the 2017 edition lists what it covers, and it takes five minutes:

Appliances in the right place under the nozzles they're protected by.
Manual pull station visible and unobstructed.
Service tag present and in date.
Pressure gauges in the operating range, where the system has them.
Nozzle blow-off caps in place. Ansul's guide calls out the nozzle caps specifically: they keep grease out of the nozzles.

Write the date down. A monthly log is the evidence that you did it.

Fusible links: annual or every six months?

Fusible links are the small metal heat detectors in the hood that melt in a fire and trigger the system. Online answers disagree on how often they must be replaced, because the rule differs by state:

Minnesota's State Fire Marshal: "replaced at least annually."
Utah's administrative code: replaced semiannually or at the manufacturer's interval, with each link stamped with its installation year. A link dated the previous year can't be used after 1 February.

Your fire protection company will know which applies. If your invoice shows the links replaced at every service, that's normal in states with the semiannual rule.

Moved or changed an appliance? The system may no longer cover it

Each nozzle is aimed at a specific appliance in a specific position. Swap a fryer for a charbroiler, move the range a few feet, or add a piece of equipment, and part of the line can end up unprotected. Ansul's guide says to contact an authorised distributor for a system update evaluation whenever changes are planned, and the semi-annual inspection checks for exactly this.

UL 300

Kitchen suppression systems must be listed to UL 300, the fire test standard for systems protecting commercial cooking equipment. NFPA 17A requires it, and Minnesota's fire marshal refers to these systems simply as "UL 300 systems." If you have an older system, ask your service company whether it is UL 300 listed.

The K-class extinguisher

Kitchens cooking with oils and fats also need a Class K portable extinguisher. Minnesota requires one within 30 feet of the cooking appliances. The suppression system is the first line of defence; the K extinguisher is for after it has discharged, or for a fire it doesn't reach.

If the system goes off

From Ansul's owner's guide:

Evacuate the building and call the fire department.
To fire it manually, pull the handle or ring on the pull station straight out.
Afterwards, call your authorised distributor to inspect and recharge the system and to find out why it went off. The kitchen isn't protected until it's recharged.
Clean up within 24 hours, using warm water and detergent. The wet-chemical agent is corrosive to kitchen surfaces if left.

How this fits with hood cleaning

Hood cleaning and suppression service are separate jobs, often by separate companies, on separate schedules. Ansul's guide links them in one direction: the system should be serviced after a major hood and duct cleaning. See how often should restaurant hoods be cleaned for the NFPA 96 cleaning schedule.