WHAT ARE HOOD VENTILATION SYSTEMS?
Hood ventilation systems stand out as one of the most critical infrastructure solutions in industrial kitchens. In restaurants, hotels, dining halls, and food production areas, they ensure that oily vapor, smoke, odors, and hot air generated during cooking are removed from the environment in a controlled manner. These systems not only clean the indoor air but also contribute to creating a more balanced temperature and a more comfortable atmosphere in the working area.
In kitchens with intensive use, oil particles mixed with the air tend to accumulate over time on surfaces and inside ducts. This situation increases the need for cleaning and may create a long-term safety risk. Especially in areas where regular air circulation is not provided, problems such as heavy odors, high temperature, and decreased air quality are frequently observed. Therefore, correct design and proper capacity selection of hood systems are of great importance.
When creating a professional hood ventilation system, air flow rate, duct structure, filter type, and fan selection should be evaluated together. It is not enough for the system to be powerful; it must also operate in a balanced, efficient, and sustainable manner. At this point, engineering calculations directly affect the performance of the system.
Hood systems are generally classified according to different needs as filtered hoods, filterless hoods, and double-wall hoods. Filtered systems stand out in oily environments, while filterless systems are mostly preferred in areas with high vapor density. Double-wall hoods are used in applications requiring higher performance and durability.
From this perspective, a properly designed hood ventilation system is not only equipment that removes polluted air, but also an important investment that provides businesses with a healthier environment, a more stable working order, and lower long-term operating costs.
FILTERED HOODS (FOR OILY ENVIRONMENTS)
Filtered hoods are systems widely used in industrial kitchens and especially designed to control polluted air generated during frying, grilling, wok cooking, and similar oily cooking processes. These types of hood systems effectively capture oil particles, smoke, and odors mixed with the indoor air, helping to keep the working area clean and contributing to the protection of the ventilation infrastructure. Among industrial kitchen hood solutions, filtered systems are considered one of the most critical components in terms of fire safety.
The labyrinth type, or baffle filters, used in these systems mechanically separate oil droplets by changing the direction of air flow. In this way, the transfer of oil particles into ventilation ducts is largely prevented. Reducing oil accumulation inside the duct both protects system efficiency and minimizes possible fire risks in the long term. Especially in professional kitchens, this detail plays a decisive role in the sustainability of the system.
Another important issue to consider in filtered hoods is the oil drainage system. Oils captured on the filter surface are collected at a specific point through inclined surfaces and special oil channels located inside the hood body. Thanks to the flow directed from there to the oil reservoir, the system operates more hygienically and cleaning processes become easier. This structure also shortens maintenance periods and helps keep operating costs under control.
Material selection is also very important in these systems. While 304 grade stainless steel is generally preferred in the production of filtered hoods, the use of 316 grade stainless steel offers a longer-lasting solution in areas where chemical vapors are intense or where more demanding operating conditions exist. Depending on the nature of the application, correct material selection directly affects system performance.
Regular maintenance and cleaning are essential for filtered hood systems to operate efficiently. If the filters are not cleaned at certain intervals, air passage becomes difficult, suction capacity decreases, and imbalances may occur in the system. Therefore, during the design stage, an easily removable filter structure and accessible design details must be taken into consideration. This approach provides ease of use and contributes to the long-term high-performance operation of the system.
FILTERLESS HOODS (FOR VAPOR AND CONDENSATION PURPOSES)
Filterless hoods are special solutions within industrial kitchen ventilation systems that are mostly preferred in processes that do not contain oil. These systems, especially used in dishwashing areas, steam boilers, boiling lines, and production areas where intense vapor is generated, ensure that humid air formed in the environment is removed in a controlled manner. The main purpose of filterless hood systems is to manage water vapor and condensation risk in order to protect both the working environment and building components.
Since there is no need for oil capture in this type of hood, conventional filter systems are not used. This allows the system to have a simpler structure and reduces maintenance requirements. However, this simplicity does not mean that the design is basic. On the contrary, the most critical issue in filterless hood design is condensation control. In environments with high vapor density, special inclined surfaces and integrated drainage channels are used to prevent water droplets that may form on the inner surfaces of the hood from dripping back. In this way, hygiene is preserved and unwanted water accumulation in the working area is prevented.
Filterless hood systems generally operate with lower pressure losses, which provides an important advantage in fan selection. Lower resistance contributes to more efficient system operation and optimization of energy consumption. However, in case of incorrect capacity selection or insufficient air extraction, problems such as moisture accumulation in the environment, condensation on surfaces, and mold formation over time may occur. Therefore, correct air flow calculations and suitable duct design are also of great importance in these systems.
Material selection is also a determining factor in filterless hood applications. In these systems, which are constantly exposed to moisture and vapor, 304 grade stainless steel is generally preferred. In more aggressive environments or areas containing chemical vapors, the use of 316 grade stainless steel offers a longer-lasting and more durable solution. When the correct material and correct design come together, filterless hood systems become reliable ventilation solutions that can serve without problems for many years.
DOUBLE-WALL (FRESH AIR SUPPLY) HOOD SYSTEMS
Double-wall hood systems are special systems developed within industrial kitchen ventilation solutions to maintain energy efficiency and indoor pressure balance, and they are also known as fresh air supply hoods. In these systems, the hood works not only as equipment that extracts polluted air but also as an active ventilation element that supplies fresh air in a controlled manner. Especially preferred in restaurants, hotel kitchens, and high-capacity cooking areas, these systems provide much more balanced air management compared to conventional hoods.
In these types of hoods, extraction is generally performed from the middle section, while fresh air is supplied through special perforations placed on the front surface, lower part, or visible user-facing areas of the hood. In this way, while the hood is operating, the completely conditioned air in the environment is prevented from being extracted and discharged outside. At the same time, negative pressure problems that may occur inside the kitchen are largely eliminated. Thanks to balanced air supply, employee comfort increases and uncontrolled air entry from doors, windows, and other openings is minimized.
In fresh air supply hood systems, the amount of air supplied is designed to be close to the extraction air flow rate. This air can be taken directly from the outdoor environment or, in certain applications, can be pre-conditioned. Especially in projects where air conditioning is required, fresh air is brought to the desired temperature values by using electric heaters, DX coils, or hot water coils. This approach both increases energy efficiency and prevents sudden temperature changes in the kitchen environment.
Thanks to these systems, air losses that may occur indoors during hood operation are controlled, and the heating-cooling load of the business does not increase unnecessarily. At the same time, the suction performance of the hood becomes more stable and air flow is directed in a more controlled manner. A properly designed fresh air supply hood system stands out as an advanced engineering solution that increases ventilation efficiency and optimizes energy costs.
VENTILATION DUCTS (HOOD CONNECTION)
DKP AIR DUCTS
DKP, or deep drawing sheet metal, air ducts are rectangular-section duct systems used especially in hood exhaust lines within industrial kitchen ventilation systems and are suitable for carrying high-temperature, oil-laden air. These ducts allow high air flow rates to be transported and provide long-lasting and safe use with correct manufacturing and installation techniques. In industrial kitchen hood systems, DKP air ducts play a critical role in terms of fire safety and hygiene.
One of the most important features of DKP air ducts is that they are manufactured with a self-flanged structure. At duct connection points, high-temperature-resistant ambient gaskets placed between two ducts are generally supported with silicone-based sealing materials to prevent air and oil leakage. In addition, welded corner connection points prevent the oily air carried inside the duct from leaking to the outdoor environment. This structure provides a major advantage, especially in kitchen exhaust systems with high fire risk.
Maintenance and cleaning access is of great importance in this type of duct. Therefore, hinged or screw-type inspection covers are placed at certain points along the duct lines. Thanks to these covers, internal duct cleaning and periodic maintenance operations can be performed easily. This detail should not be neglected, especially in oily systems.
At points where the duct system rises to the roof, a T-elbow application is generally used. Oil drainage traps placed at the bottom of these elbows ensure controlled discharge of oil accumulated inside the duct. In addition, providing a minimum slope of 3% on horizontal lines is a critical application for directing oil to drainage points without allowing it to accumulate inside the duct.
In DKP air ducts, transported air velocities are generally selected in the range of 6–10 m/s, while these values are optimized according to the project in systems with high oil load. Internal duct temperatures may vary between 60°C and 120°C depending on the application. Therefore, the outer surfaces of the ducts are completely covered with rock wool insulation. Rock wool insulation is resistant to high temperatures and can generally withstand heat in the range of 250°C – 600°C. In this way, in case of a possible flame-up inside the duct, cables, equipment, and structural elements located in the surrounding environment are prevented from being affected by heat.
The aluminum embossed cladding applied over the insulation provides protection against mechanical impacts and increases resistance against outdoor conditions. Thanks to this multilayer structure, DKP air ducts become an indispensable part of industrial kitchen ventilation systems in terms of both fire safety and long service life.
ROUND FLANGED AIRTIGHT AIR DUCTS
Round flanged airtight air ducts are among the aerodynamic duct solutions preferred especially in hood exhaust lines within industrial kitchen ventilation systems, providing high airtightness and low pressure loss. Thanks to their circular cross-section, air flow occurs more smoothly, turbulence effects are reduced, and friction losses along the duct are minimized. This feature both reduces fan energy consumption and increases the overall efficiency of the system.
At the connection points of round flanged ducts, installation is carried out through flanges integrated into the duct ends. In these connections, full sealing is achieved by using high-temperature-resistant EPDM or silicone-based gaskets. Proper tightening of flange connections and correct gasket application are of great importance, especially in hood systems carrying oily air, in order to prevent air and oil leakage. In this way, the system operates both hygienically and safely.
Air velocities transported in round air ducts are generally selected in the range of 7–12 m/s, and these values are optimized according to the system capacity. Internal duct temperatures may vary between 50°C and 120°C depending on the application. Therefore, just like DKP ducts, the outer surfaces of the ducts are completely covered with rock wool or glass wool insulation materials. The insulation materials used generally provide resistance to temperatures of 250°C and above, contributing to the protection of surrounding equipment in the event of a possible fire or flame-up.
The aluminum embossed cladding applied over the insulation protects the duct against outdoor effects, mechanical impacts, and moisture formation. This cladding also improves the aesthetic appearance of the system. Maintenance and cleaning access should not be neglected in round ducts either. Therefore, screw-type or gasketed cleaning covers are placed at suitable intervals. In addition, oil drainage outlets should be created at certain points to control oil accumulation that may occur in duct lines.
Properly designed round flanged airtight air ducts stand out as an important solution in industrial kitchen ventilation systems with their advantages of low energy consumption, high air transport efficiency, and long service life.
FIRE DAMPERS
MECHANICAL FUSIBLE LINK FIRE DAMPER
A mechanical fusible link fire damper is passive fire safety equipment that operates entirely on mechanical principles and is used in ventilation duct systems to limit the spread of flames and hot gases during a fire. These dampers can be applied in both square or rectangular-section air ducts and round air ducts, and they are designed according to the duct geometry. The thermal fuse element located inside the mechanical fusible link fire damper generally melts or breaks and becomes inactive in the temperature range of 70°C – 90°C. When this fuse is released, the pre-tensioned spring mechanism, or spring return system, inside the system becomes active and the damper blade closes suddenly and in a controlled manner.
The blade positioned on the central axis of the damper is kept in the open position under normal operating conditions. When the thermal fuse breaks, it rapidly moves to the closed position under the effect of spring force. Thanks to this mechanism, flame progression, hot smoke transfer, and the spread of fire to different spaces through the ventilation duct line are prevented. The main purpose of using a mechanical fusible link fire damper is to stop the progression of fire along the duct and provide isolation between fire zones.
In this type of damper, the thermal fuse element is single-use and must be replaced with a new one after a fire or test. During fuse replacement, the damper blade is first manually moved to the open position, then a new thermal fuse with a suitable temperature rating is installed and the system is reactivated. During this process, it must be ensured that the mechanism moves freely and that the spring system operates correctly.
The mechanical fusible link fire damper is a critical safety component widely preferred especially in industrial kitchen ventilation systems and duct lines with high fire risk, thanks to its electricity-independent operating principle, high reliability, and low maintenance requirement.
SERVOMOTOR FIRE DAMPER
A servomotor fire damper is automation-supported active fire safety equipment used in ventilation duct systems to prevent flames, hot smoke, and high-temperature gases from being transported to other spaces during a fire. These types of fire dampers can be used in both square-section air ducts and round air ducts. Especially in buildings where the fire scenario is managed together with the building automation system, the servomotor fire damper offers a more controlled and monitorable solution. The main purpose of these systems is to automatically isolate the ventilation line during a fire and prevent the fire from progressing along the duct.
The operation of a servomotor fire damper is provided by the spring return actuator, or in other words, the servomotor mechanism located on it. Under normal operating conditions, the servomotor keeps the damper blade in the open position. The system usually operates with a warning signal coming from the fire alarm panel, smoke detector, heat detector, building automation system (BMS), or directly from a fire scenario output. When this signal from the fire detection system reaches the device, the servomotor cuts the power or receives a closing command depending on the control logic, allowing the blade to close. At this point, the spring mechanism inside the actuator is activated and the damper blade automatically moves to the closed position. Thus, the air flow inside the duct is stopped, flame progression is limited, and hot smoke is prevented from being transferred to other volumes.
Actuators used in servomotor fire dampers generally operate with 24 V AC/DC or 230 V AC power supply. In addition to open-close control, some models include position feedback, auxiliary contact, open/closed status signal, and fault monitoring contact. In this way, the position of the damper can be monitored through the building automation system. Especially in large buildings, this feedback feature provides a significant advantage in terms of correct operation of the fire scenario. During system operation, the airtight seating of the blade enables the duct line to act as a separator between fire zones.
After the servomotor fire damper is activated and closed, the system should not be reactivated randomly. First, the source of the fire alarm or the signal causing false activation must be identified. The damper should not be moved back to the open position without checking the smoke detector, heat detector, or automation line. Then, the damper body, blade shaft, connecting arms, and actuator mechanism should be mechanically inspected. If the system has been exposed to fire, the sealing elements and body deformation of the damper must also be checked. Afterwards, the servomotor is energized or returned to the open position with the help of the manual setting lever. In some models, the reset operation is performed directly through the actuator, while in some models it is performed through the fire automation panel. After reactivation, an open-close cycle test of the damper must be performed to verify that the blade fully opens and fully closes again during the alarm scenario.
Servomotor fire dampers should be selected in accordance with EN 15650, EN 13501-3, EN 1366-2, and relevant HVAC and fire safety standards depending on the application. The fire resistance class, airtightness performance, actuator type, and feedback contacts of the product should be determined according to project requirements. A correctly selected and properly connected servomotor fire damper functions not only as part of the ventilation system, but also as an important component of the building’s integrated fire safety scenario.
HOOD FAN SYSTEMS
CABINET TYPE EXHAUST FANS (PLUG FAN SYSTEMS)
Cabinet type exhaust fans are among modern fan solutions used in industrial kitchen ventilation systems, offering high efficiency and compact design advantages. Cabinet type exhaust fans, especially preferred in hood exhaust systems, directly affect system performance by ensuring the controlled transportation of oily vapor, smoke, and polluted air. Plug fans used in these types of hood fan systems are designed to be directly coupled to the motor shaft, or direct drive, and the motor group is always positioned outside the air stream. In this way, the motor does not come into contact with oily air, and a long-lasting operating structure with low maintenance requirements is achieved.
Metal oil-retaining filters located at the inlet section of cabinet type exhaust fans mechanically separate oil particles in the air, ensuring protection of the fan and duct system. Oils captured in the filters are collected in the oil collection reservoir inside the device and discharged from there through a siphoned drainage line. This structure both contributes to maintaining hygiene and helps minimize fire risk by reducing oil accumulation within the system.
The device body is generally manufactured from an aluminum profile or steel construction frame structure and provides high strength in terms of durability. Cabinet type exhaust fans are mostly produced as double-wall units, and both heat and sound insulation are provided thanks to rock wool insulation placed between the two walls. This insulation structure reduces the outer surface temperature of the device while also reducing the noise generated during operation.
Cabinet type exhaust fan systems are suitable for operation with a frequency inverter (VFD), and the fan speed can be adjusted according to system requirements thanks to variable air flow control. This feature both optimizes energy consumption and offers flexible use in different operating scenarios. A properly designed cabinet type exhaust fan system provides high efficiency, low energy consumption, and long-term reliable operating performance in industrial kitchen hood applications.
CENTRIFUGAL TYPE FANS
Centrifugal type fans are durable and performance-oriented fan solutions preferred in industrial kitchen ventilation systems, especially in hood exhaust applications requiring high static pressure. In systems containing long duct lines, numerous elbows, filter elements, and accessories, centrifugal type fans play a critical role in ensuring the continuity of air flow. These types of hood fan systems offer a reliable solution in industrial kitchen projects thanks to their ability to operate stably under high pressure.
The body structure of centrifugal type fans is generally manufactured from high-strength steel sheet and designed in a spiral, or volute, form. The impeller structure used inside the fan is mostly backward curved, and thanks to this geometry, aerodynamic efficiency is increased and oil and particle retention inside the fan is prevented. This structure provides important advantages in terms of performance continuity, especially in hood systems carrying oily vapor. The inspection hatch located on the fan body allows periodic maintenance, cleaning, and inspection operations to be carried out easily.
The motor group can be selected as direct coupled or belt-pulley driven depending on operating conditions. In fans positioned outdoors, a protective cover must be used to protect the motor against rain, moisture, and UV effects. In addition, technical parameters such as motor insulation class, IP protection level, and operating temperature should be determined according to project conditions.
One of the most critical factors in the installation of centrifugal type fans is vibration control. Therefore, vibration isolators must be used between the fan base and the floor. These elements prevent vibrations generated during fan operation from being transmitted to the structure, reducing sound level and extending system life. A correctly selected centrifugal type fan within hood fan systems provides a significant advantage in terms of high performance, long service life, and reliable operation.
HEAT RECOVERY HOOD FAN SYSTEMS
Heat recovery hood fan systems are engineering solutions that maximize energy efficiency within industrial kitchen ventilation systems and stand out with advanced control infrastructure. Especially in commercial kitchens that operate continuously, operating costs are significantly reduced by recovering the heat energy contained in the exhausted air. Therefore, heat recovery hood fan systems are among the preferred systems in modern HVAC projects and buildings with high performance expectations.
In these systems, polluted air extracted from the hood is drawn by the exhaust fan, passed through oil and particle filters, and then passed through the plate heat exchanger located at the center of the device to recover its heat. The fresh air fan located within the same device passes the air taken from the outdoor environment through the same exchanger, providing pre-conditioning. In this way, the system creates significant energy savings, especially during winter months. When required, the fresh air line is supported with a DX coil, hot water coil, or electric heater to bring it to the desired temperature level.
One of the most important features of heat recovery hood fan systems is that they operate with precise automation infrastructure. These systems generally have a PLC-based control system. Thanks to PLC control, fan speeds, temperature values, filter contamination, and air quality are continuously monitored and optimized. The system can also be integrated into building automation systems (BMS) and SCADA infrastructures. Thanks to this integration, all system parameters can be centrally monitored, reported, and remotely intervened when necessary.
Thanks to these features, heat recovery hood fan systems are widely used especially in smart building projects. These systems provide significant advantages in buildings where energy efficiency, sustainability, and environmental impact criteria are at the forefront. At this point, HVAC systems that provide energy efficiency are of great importance within the scope of LEED (Leadership in Energy and Environmental Design), the international green building certification system. In LEED-certified buildings, systems that provide energy recovery and are controlled by automation are among the critical elements that contribute to scoring.
Heat recovery hood fan systems stand out among advanced technology ventilation solutions suitable for sustainable and smart building concepts, thanks to both their energy-saving structure and advanced automation capability.
DOUBLE-WALL HOOD VENTILATION SYSTEMS WITH INDEPENDENT FANS
Double-wall hood ventilation systems with independent fans are advanced systems within industrial kitchen ventilation solutions that offer high control capability by managing exhaust and fresh air flow independently from each other. In these systems, the exhaust fan that extracts polluted air from the hood and the supply fan, or make-up air fan, that provides fresh air to the hood in a controlled manner are positioned separately and operated independently from each other. This approach provides significant advantages especially in large-volume kitchens and projects requiring sensitive pressure balance.
In double-wall hood systems with independent fans, the most critical design parameter is balancing the exhausted air flow rate with the fresh air flow rate supplied to the environment. In this way, negative pressure formation inside the kitchen is prevented, uncontrolled air entry from doors and openings is avoided, and the suction performance of the hood becomes more stable. At the same time, energy losses are reduced by minimizing the direct discharge of conditioned indoor air to the outside. This provides a serious energy advantage, especially in projects with high air conditioning loads.
The fresh air line can be supported with a DX coil, hot water coil, or electric heater depending on application requirements. Thus, the air supplied through the hood is included in the system after being pre-conditioned in a way that does not disturb indoor comfort. This structure increases employee comfort while also preventing sudden temperature changes.
Double-wall hood ventilation systems with independent fans are generally controlled by PLC-based automation systems. Fan speeds, air flow rates, temperature values, and pressure balance are continuously monitored and optimized. The systems can be integrated into building automation systems (BMS) and SCADA infrastructures, offering central control and monitoring capability. Thanks to these features, these systems are widely preferred especially in smart building projects and applications where energy efficiency criteria are at the forefront.
A properly designed double-wall hood ventilation system with independent fans provides high-performance air management and offers a high-level solution in terms of energy efficiency, comfort, and sustainability.
ELECTROSTATIC AND CARBON FILTER SYSTEMS
CARBON FILTER SYSTEMS
Carbon filter systems are complementary filtration solutions used in industrial kitchen ventilation systems especially for odor control purposes. While electrostatic filters undertake the task of capturing oil and particles, carbon filters adsorb volatile organic compounds (VOC), gas-phase pollutants, and odor molecules remaining in the air and remove them from the environment.
Activated carbon used in carbon filters is generally obtained by processing coconut shell, coal, or wood-based raw materials at high temperatures and then subjecting them to an activation process. As a result of this process, millions of microscopic pores form inside the carbon structure. Thanks to this porous structure, activated carbon has a very high surface area. Typically, the surface area of 1 gram of activated carbon can reach 800 – 1200 m². This feature allows carbon to retain odor molecules on its surface.
Carbon filter systems can generally reduce odors in the air within an efficiency range of 70% – 95%. However, this efficiency varies depending on odor intensity, air flow rate, and the amount of carbon used. In applications with intense odors, carbon filters can be designed as single-pass, double-pass, or triple-pass systems. Especially in kitchens with heavy odors, maximum odor removal is achieved by passing the air through multiple carbon layers.
The performance of carbon filters decreases over time because the carbon surface reaches saturation. Therefore, carbon filters must be replaced at certain intervals. Although the average replacement period varies depending on usage intensity, it generally ranges from 3 to 6 months.
Carbon filter systems provide the highest efficiency when used together with electrostatic filters. Thanks to this combination, both particle and odor control are achieved, and hood ventilation systems gain an environmentally friendly and high-performance structure.
WET FILTER SYSTEMS (WET SCRUBBER)
Wet filter systems are among alternative filtration solutions used in industrial kitchen ventilation systems, especially in applications with intense oily smoke and high particle load. These systems are based on the principle of cleaning polluted air by bringing it into contact with water and may be preferred especially in businesses with heavy kitchen loads. Unlike conventional dry filter systems, wet filter systems create both physical and partially chemical filtration effects.
The operating principle of the system is based on taking the polluted air from the hood into the device and passing it through a water curtain, spray nozzles, or a cyclonic flow zone. During this process, oil particles, smoke, and some pollutants in the air come into contact with water droplets, become heavier, and are carried into the water reservoir inside the system. In this way, coarse and medium-sized particles in the air are retained and the outlet air is made cleaner.
The main equipment in wet filter systems can be listed as the water reservoir, circulation pump, spray nozzles, drift eliminator, level control float, and drainage line. The system generally operates in a closed circuit, and the water is continuously circulated with the help of the pump. When the water level decreases, the automatic water supply mechanism in the system, controlled by a float or solenoid valve, is activated and replenishes the missing water.
In these systems, water consumption varies depending on the type of system used, but it is generally at a low-to-medium level and operates on a recirculation basis rather than continuous flow. However, oil and particle accumulation occurs in the water over time. Therefore, the system must be drained and the water must be renewed at certain intervals. In addition, in some applications, oil skimmer systems can be used to separate oil from the surface.
The efficiency of wet filter systems is generally at a particle capture level of 70% – 90%. However, they are not sufficient alone in terms of very fine particles and odor removal. Therefore, in most projects, it is recommended to use them together with electrostatic filter or carbon filter systems. If not designed correctly, they may require high maintenance and must be operated carefully in terms of hygiene.
In general, wet filter systems provide an effective pre-filtration solution when applied correctly. However, for a high-performance and sustainable hood ventilation system, using them together with other filtration technologies generally provides healthier and more efficient results.
HOOD FIRE EXTINGUISHING SYSTEMS
Hood fire extinguishing systems are active fire safety solutions developed against fire risks that may occur in industrial kitchen ventilation systems, providing local and automatic intervention. Especially in environments where oily vapor, high temperature, and kitchen equipment operating with open flames are present, the hood and duct line are among the most critical areas in terms of fire. Therefore, hood fire extinguishing systems are considered a mandatory engineering application not only for equipment protection but also for life and building safety.
The operating principle of these systems is based on detecting the start of a fire quickly and suppressing the fire at its source. During a fire, a special extinguishing agent is sprayed through nozzles placed inside the hood and above the cooking equipment. The system is generally triggered by a thermal detection line, or fusible link, or a linear heat detector. When a certain temperature value is reached, generally in the range of 138°C – 182°C, this detection element is activated and the system operates automatically. At the same time, the systems can also be activated manually with a manual release handle.
The extinguishing agent used in hood fire extinguishing systems is generally wet chemical based. These chemicals are specially developed for grease fires, or Class F / K type fires. During extinguishing, the chemical agent reacts with the hot oil surface and forms saponification, creating a layer on the surface that cuts off contact with oxygen. In this way, the flame is suppressed and the risk of re-ignition is minimized.
System components consist of a pressurized extinguishing cylinder, distribution piping line, nozzle heads, triggering mechanism, control valve, and safety lock systems. In addition, when the system is activated, it generally operates in integration with a gas line shut-off valve and an electrical shut-off relay, automatically cutting off the energy feeding the fire source.
After the system is triggered, before it is reactivated, it must first be ensured that the fire is completely extinguished and the system must be inspected in detail. The used extinguishing agent cylinder must be refilled, and the triggering mechanism, whether fusible link or sensors, must be replaced. The piping line and nozzles must be cleaned, then the system must be pressurized again and tested. These operations are generally performed by an authorized technical service.
A properly designed hood fire extinguishing system controls the fire before it grows, reducing equipment damage and raising business safety to the highest level. These systems, which are an indispensable part of industrial kitchen ventilation systems, are among the fundamental elements of the modern fire safety approach.
