The Science of Kitchen Fire Suppression Systems: How Do They Work?

By Matthew Wilson June 18, 2025Fire Safety

When having a restaurant kitchen of any size it is important to have some type of fire protection with it. Depending on the size of the kitchen your fire protection could be simple like a single fire extinguisher or more complicated like a kitchen suppression system. In this blog we’ll discuss what a Kitchen Suppression System is, why they are important, and how they work. 

A Kitchen Suppression System is a specialized fire protection system designed to detect and extinguish fires in commercial kitchens, particularly those involving cooking equipment, grease, and other flammable materials. 

Kitchen Suppression Systems are important because they are a safeguard to fires in the kitchen. It not only protects the chefs but also protects everyone in the building, and the building itself. Around 5,900 restaurant fires are reported in the U.S Every year so it is important to have the necessary equipment to protect those you care about. 

Here’s how they generally work: 

1. Detection:

• Heat Detectors: The most common method involves strategically placed heat detectors (often fusible links or rate-of-rise detectors) above the cooking appliances and in the exhaust hood.
  • Fusible Links: These are made of two pieces of metal joined by a solder that melts at a specific temperature. When the ambient temperature reaches this point, the solder melts, separating the links and triggering the system.
  • Rate-of-Rise Detectors: These respond to a rapid increase in temperature, even if the absolute temperature isn’t extremely high.
• Manual Pull Stations: For immediate activation, there are usually manual pull stations located near exits or in an easily accessible area, allowing occupants to trigger the system if they spot a fire.

2. Activation:

Once a fire is detected (either automatically by heat or manually by a pull station), the system activates. This activation typically involves a mechanical or electrical release mechanism that performs several crucial functions:

• Fuel Shut-off: The system is usually interconnected with the fuel supply (gas or electricity) to the cooking appliances. Upon activation, it automatically shuts off the fuel source, preventing the fire from being fed and escalating. This is a critical step in fire suppression.
• Alarm Activation: Fire alarms are triggered to alert occupants and initiate evacuation.
• Ventilation Shut-down: The kitchen’s exhaust fan system is often shut down to prevent the spread of smoke and fire through the ductwork.
• Extinguishant Discharge: This is the core of the suppression.

3. Extinguishant Discharge:

• Wet Chemical Agent: Modern kitchen suppression systems almost exclusively use a wet chemical agent. This agent is stored under pressure in cylinders and discharged through strategically placed nozzles directly over the cooking surfaces and into the exhaust plenum and ductwork.
• How Wet Chemical Works:
  • Saponification: When the wet chemical agent hits the hot grease or oil, it undergoes a chemical reaction called saponification. This reaction forms a foam-like blanket over the burning fuel.
  • Cooling: The water content in the wet chemical also provides a cooling effect, reducing the temperature of the burning oil below its ignition point.
  • Oxygen Deprivation: The foam blanket created by saponification effectively smothers the fire by preventing oxygen from reaching the fuel.
  • Re-ignition Prevention: A key advantage of wet chemical agents is their ability to prevent re-ignition, as the foam blanket remains on the surface and continues to cool.

4. Post-Discharge and Reset:

• After the fire is suppressed, the system must be professionally inspected, cleaned, and reset by a qualified technician. The wet chemical residue needs to be cleaned up, and any discharged components or pressure cylinders must be replaced.
• Regular maintenance and inspections (typically semi-annual) are required by code to ensure the system is always in good working order.

Key Components of a Kitchen Suppression System:

• Control Panel: The brain of the system, receiving signals from detectors and initiating the discharge sequence.
• Agent Storage Cylinder: Contains the wet chemical agent under pressure.
• Nozzles: Designed to deliver the extinguishing agent in a specific pattern to cover the protected areas.
• Detection Devices: Heat detectors (fusible links, rate-of-rise) and manual pull stations.
• Piping and Tubing: Connects the agent cylinder to the nozzles.
• Automatic Fuel Shut-off Valves: For gas lines or electrical relays for electric appliances.

By combining rapid detection, automatic fuel shut-off, and the effective firefighting properties of wet chemical agents, kitchen suppression systems provide a vital layer of protection against devastating kitchen fires in commercial settings.

Protect Your Kitchen with Fire Shield Fire Protection Ready to safeguard your commercial kitchen? Schedule a call with Fire Shield Fire Protection today! Our experts will walk you through how we design, install, inspect, clean, and maintain top-of-the-line kitchen suppression systems tailored to your needs.