Kitchen Hood Fire Suppression Systems and Maintenance in Restaurants

A kitchen hood fire suppression system in a restaurant is designed to tackle fires involving cooking equipment and grease within the hood. When a fire is detected, the wet chemical extinguishing agent is discharged through designated nozzles into the hood and cooking area. Connected gas shut-off and alarm outputs can also be activated.

Grease that accumulates inside the hood can ignite when exposed to heat from equipment such as cookers and fryers. The system must therefore be installed to suit the equipment layout, and the detection line, cylinder, nozzles and connections must be checked regularly. The system design and alarm connection may vary depending on the project.

Grease fire risks in commercial kitchens

Grease residues can accumulate over time in hood filters, grease ducts and around cooking equipment. A flame that starts over a fryer or cooker can spread to the inside of the hood and into the duct. A kitchen hood fire suppression system is intended to tackle fires at an early stage using detection elements and extinguishing nozzles positioned to suit these areas.

Protecting the hood alone may not be sufficient. The protected area should be determined by assessing the type of cooking equipment, hood dimensions, filter positions and duct route. If equipment is moved or the kitchen layout changes, check that the nozzles still cover the new arrangement.

Cleaning the hood and filters should also be part of routine operations to reduce fire risk. A fire suppression system does not remove grease build-up and is not a substitute for cleaning or fire prevention measures.

How does a wet chemical system work?

Wet chemical systems use an extinguishing agent suitable for cooking oils and equipment in commercial kitchens. Depending on the design, the system may operate using a heat-sensitive detection line or element. Once detection occurs, the extinguishing agent in the cylinder is routed through pipework to the relevant nozzles and discharged into the protected area.

Wet chemical suppression forms a blanket over the surface of the hot oil and helps it cool. This helps reduce the risk of re-ignition. For effective performance, the correct quantity of extinguishing agent, nozzle type and orientation must be matched to the equipment being protected. These details should be specified in accordance with the installation design and the manufacturer’s documentation.

The design may also include shutting off the gas supply to the source of fuel when the suppression system activates. The system may be connected to a suitable gas shut-off device or, for electric cooking equipment, to the relevant shut-off output. The equipment to be shut down and how the shut-off is to be carried out should be defined in the project; after activation, equipment must not be put back into operation until it has been inspected by authorised personnel.

Heat detection, manual activation and gas shut-off

The heat detection line is positioned to suit a fire within the canopy or cooking area. Some systems use fusible links that operate at a specified temperature. When a detection element activates, it triggers the suppression system. The type and layout of the line depend on the system manufacturer’s documentation and the project.

The manual activation device allows the system to be operated by hand as an alternative to automatic detection. It should be installed in an accessible location, kept unobstructed, and its use should be familiar to operating staff. The position of the pull handle or button should be determined with safe access in the kitchen in mind. Staff training should cover when and how to use the system.

The gas shut-off connection may include a device that shuts off the kitchen gas supply when the suppression system activates. Its correct operation is checked during maintenance. Testing must be carried out under safe working conditions for the gas line and cooking equipment, by competent service personnel and in accordance with the system documentation.

Connection to the fire alarm system

The kitchen canopy suppression system can be connected to the fire alarm control panel via a contact or suitable interface. This allows activation of the system to be monitored at the panel, audible and visual warnings elsewhere in the building to be activated, or other specified scenarios to be initiated. The event that triggers each output must be clearly defined in the project and panel programming.

The purpose of connecting to the fire alarm control panel is not to duplicate the suppression system’s function, but to pass information about the event to the building-wide fire response scenario. For example, system activation can be monitored at the panel; whether the building alarm or another output is activated depends on the site design. The same scenario should not be assumed for every installation.

During commissioning and maintenance, check that the suppression system output is correctly indicated at the fire alarm control panel and that the relevant scenario operates as expected. The connection must be verified again if changes are made to the panel, interface or wiring. For guidance on maintaining fire alarm systems, see our article on fire alarm control panel and detector maintenance in an addressable fire alarm system.

Which points are checked during maintenance?

The scope of maintenance is determined by the system model and the manufacturer’s instructions. The purpose of the inspection is not simply to confirm that the cylinder is in place. The detection line, discharge paths, manual activation device and, where fitted, the connections to the fire alarm control panel and gas shut-off must all be assessed together.

• Cylinder and pressure gauge: Check the cylinder’s physical condition, mounting, label and pressure gauge. Compare the pressure reading with the acceptable range specified in the manufacturer’s documentation. If there is any damage or the gauge is unsuitable, the system should be assessed by a service technician.
• Nozzles and caps: Check that the nozzles are in place, correctly oriented and not blocked by grease or dirt. Inspect the condition of the protective caps. Following any equipment changes, reassess whether the nozzle still covers the target area.
• Fusible link or detection line: Check that the line is not broken, loose, crushed or dirty. Compare the positions and connections of the detection elements with the system documentation. Hanging equipment from the line or moving it during kitchen alterations may affect detection.
• Manual activation and gas shut-off: Check that the manual activation device is accessible, that the connections are in good condition and that the gas shut-off device operates correctly. Testing should be carried out in accordance with a service plan that takes kitchen operations and gas safety into account.
• Alarm connection and records: Check that the input or output at the panel operates correctly and that event information is transmitted as expected. Record the work carried out, any issues identified and the corrective action required in the service record.

Tests involving discharge of the system can result in the loss of extinguishing agent and leave the kitchen temporarily unprotected. The method to be used for routine inspections should therefore be determined in advance. If discharge or replacement of parts is required, the steps for returning the system to service should also be planned. Rather than assuming a general maintenance interval, follow the manufacturer’s instructions, the project requirements and the site’s service plan.

The kitchen canopy system may protect an area separate from other suppression solutions in the building. To compare maintenance approaches for different fire suppression systems, see our fire suppression systems service page and our article on gas suppression system maintenance.

What the business can prepare before maintenance

Before maintenance, the person responsible for the business should inform the service team about the equipment used beneath the canopy and any recent changes. They should also share details of any previous system activation, faults shown at the fire alarm control panel or problems with the gas shut-off connection. This information helps direct the inspection to the right areas.

The area around the canopy must be accessible so that the equipment can be inspected safely during the service visit. If the panel connection is to be tested, it is helpful for the building’s technical manager or someone familiar with the alarm system to be present. Operating staff should also know where the manual activation device is and must not dismantle or modify the system themselves.

Request a Survey and Quote from Narstek

Based in Istanbul, Narstek Elektronik Bina Teknoloji San. ve Tic. Ltd. Şti. provides site surveys, design, installation, maintenance and fault repair services for fire detection and alarm systems. Existing fire suppression systems and connections to fire alarm control panels can be assessed based on the condition of the installation. You can also enquire about projects outside Istanbul and product supply.

When requesting a quote, please provide the business address, type of kitchen, equipment used beneath the canopy, and any known system brand and model details. If available, include photos or documents showing the cylinder label, latest maintenance record, fire alarm control panel connection and kitchen layout. It will also help with the initial assessment if you let us know whether the system is operational and whether your request concerns maintenance, a fault or a new installation.

You can fill in the survey and quote form, or submit a technical service request. You can contact Narstek on 0212 424 07 24 or via WhatsApp on 0540 001 07 24.