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Automatic kitchen fire suppression: how it works

A fryer can catch fire in seconds. See how a hood suppression system detects the fire, discharges on its own and cuts the gas, and what the law requires in a professional kitchen.

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Fire safety · Business · 4 min read

In professional kitchens, the greatest risk lies in fryers, grills and the grease built up in the hood and the extraction duct. A grease fire spreads quickly and cannot be put out with water. That is why automatic suppression systems exist, designed for this situation.

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How automatic suppression works in a kitchen hoodA heat-sensitive tube runs along the hood. If heat bursts it, the extinguishing agent cylinder discharges through the nozzles onto the kitchen appliances and the duct, and the gas and electricity are cut off. There is also a manual button. air and grease to outsideHoodFryer, grill and cookerCylinderGas shut-offand electricityButtonmanualWhat happens in a fire1Heat bursts the detectiontube2Pressure drops, cylinderfires3Nozzles coverappliances and duct4Gas and electricity cut offautomatically5Can also be triggered bybutton
  1. Runs under the hood and bursts in the heat of a fire, with no electricity needed.

  2. Sits in a cabinet and, when the tube's pressure drops, discharges the liquid agent to the nozzles.

  3. They cover the fryer, grill, cooker and extraction duct, where built-up grease can catch fire.

  4. Lets you trigger the system by hand, from a safe point by the exit.

  5. When the system fires, it cuts the fuel and power to the appliances.

  6. Extracts fumes and grease. The duct is one of the highest-risk areas in a professional kitchen.

Detects fire and puts it out with no one stepping in. A fire blanket and a grease-rated (wet chemical) extinguisher are still mandatory in the kitchen (RT-SCIE, Art. 163(5)).

What the law requires and what it recommends

MeasureStatus
Extinguisher for oils and fats (minimum rating 25F) and fire blanketMandatory in risk C kitchens (Article 163(5) of RT-SCIE, the technical fire-safety regulation for buildings)
Emergency shut-off of fuel and powerMandatory in kitchens above 20 kW (Article 90)
Automatic gas detectionMandatory in risk C premises where gas appliances operate (Article 184)
Automatic suppression on the hoodRecommended: the regulation does not expressly require it, but insurers and projects usually do

A kitchen is a risk C location when the cooking appliances have a total useful power above 20 kW.

How the system decides to discharge

A pressurised heat-sensitive detection tube runs beneath the hood. When the heat of a fire bursts it, the pressure drops and the cylinder valve opens. The extinguishing agent comes out through the nozzles and covers the equipment and the duct. At the same time, the gas and electricity are cut off. It does not need electricity to discharge, so it works even if the power fails.

Maintenance

The system must be inspected periodically by a registered company, the nozzles protected against grease (with their caps) and the hood and duct cleaned regularly. A dirty duct is fuel waiting to burn.

Can I use extinguishers alone in the kitchen?

That is the legal minimum in risk C kitchens, with the extinguisher suitable for fats and the fire blanket. An automatic system adds protection where the fire starts, even with nobody present.

Does the system suit any kitchen?

It is sized to fit: the number of appliances and the length of the hood and duct. That is why it is specified during a site visit.

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