How to choose a suitable fire smoke exhaust fan?

Choosing a suitable fire smoke exhaust fan is the key link to ensure the fire safety of buildings and the effective discharge of toxic smoke in case of fire. It needs to be comprehensively judged from multiple dimensions, such as building characteristics, fire protection specifications and use scenarios. The core can be developed around the following six core dimensions to ensure that the selection is scientific, compliant and practical:

First, according to the building specifications and design parameters, the basic needs are defined.

The selection of fire smoke exhaust fans shall strictly follow the national and local fire protection codes (such as Code for Fire Protection Design of Buildings (GB 50016-2014(2018 edition)) and Technical Standard for Smoke Prevention and Exhaust System of Buildings (GB 51251-2017), and the basic parameters shall be determined in combination with the smoke exhaust area, floor height and fire risk category of buildings:

Calculation of smoke exhaust quantity: Calculate the minimum smoke exhaust quantity according to the type of smoke exhaust area (such as atrium, garage, workshop and office area) according to the standard formula. For example:

The smoke exhaust quantity of atrium should be calculated according to its volume ≥6 air changes per hour;

The smoke exhaust volume of the garage should be calculated as a single smoke prevention partition ≥ 20,000 m/h (or as a building area ≥ 60 m/(hm2)) to avoid smoke retention caused by insufficient smoke exhaust volume.

Wind pressure matching: The pipeline resistance loss (including straight pipe resistance and local resistance of elbow/valve/fire damper) of the smoke exhaust system should be considered, and the "total pressure" of the fan should be greater than the total resistance of the system (usually 10%-15% wind pressure margin should be reserved) to prevent the smoke from being effectively transported to the outside due to insufficient wind pressure.

Limitation of installation location: it is clear whether the fan is installed on the roof, on the wall or in the machine room, and different locations need different protection levels (for example, roof ventilator needs rain protection and corrosion protection, and the fan in the machine room needs noise control).

Second, according to the usage scenario, select the suitable fan type.

Fire-fighting smoke exhaust fans can be divided into different types according to their structures and functions, and should be selected according to the scene characteristics to avoid functional mismatch:

Fan Type Core Features Applicable Scenarios

Axial-flow smoke exhaust fan has large air volume, moderate wind pressure, small volume and flexible installation in small and medium-sized smoke exhaust areas (such as offices, shops and small garages)

Centrifugal smoke exhaust fan has the advantages of high wind pressure, large air volume, strong overload resistance and stable air flow to exhaust smoke from long-distance pipelines (such as large factories, underground garages and atriums)

The high-temperature smoke exhaust fan can withstand the high temperature of 280℃ for 30min (or 150℃ for a long time), and the smoke exhaust system with automatic temperature control protection must pass through the fire compartment and need high temperature resistance (such as stairwell and smoke compartment partition).

Explosion-proof smoke exhaust fan motor, impeller and other components are explosion-proof (such as Ex d IIB T4). Places with flammable and explosive substances (such as oil depots of food processing plants and auxiliary buildings of chemical workshops).

For example, the centrifugal high-temperature smoke exhaust fan is preferred for the underground garage because of the long smoke exhaust pipeline and large resistance; In the dust workshop of food processing plant (if there is explosion risk), explosion-proof smoke exhaust fan should be selected.

Third, pay attention to the core performance indicators of fans and avoid "virtual parameters"

When selecting the type, check the test report provided by the fan manufacturer (such as CCCF certification by the National Fire Products Conformity Assessment Center), and focus on confirming the following performance indicators:

High-temperature resistance: the fire smoke exhaust fan must meet the requirements of "continuous operation for 30 min at high temperature of 280℃" (GB 51251), and some special scenes (such as chemical buildings) need to choose fans that can withstand more than 400℃ to avoid smoke exhaust failure caused by fan damage at high temperature.

Noise and vibration: If the fan is installed in a people's activity area (such as a shopping mall or an office building computer room), attention should be paid to the sound pressure level of the fan (usually ≤85dB, which is lower at night), and the fan with vibration damping base and muffler can be selected to reduce the impact on the surrounding environment.

Motor protection level: the IP protection level of the motor should be suitable for the installation environment, such as IP54 or above for roof installation (rain and dust prevention) and IP55 or above for wet environment (such as underground garage) to prevent the motor from entering water and short circuit.

Efficiency and energy consumption: Give priority to the fans with high energy efficiency (such as Grade 1 energy efficiency). Long-term use can reduce energy consumption costs, especially for systems that need 24-hour standby and operate at high frequency in case of fire. Energy efficiency is very important.

Four, combined with the system, to ensure compatibility with pipes and valves.

Fire-fighting smoke exhaust fan is not an independent equipment, but needs to form a complete system with smoke exhaust pipeline, fire damper and smoke exhaust port, and attention should be paid to "compatibility" in selection:

Interface size matching: the size of the air inlet/outlet of the fan should be consistent with the size of the smoke exhaust pipe (or smoothly transition through the reducing pipe) to avoid the sudden increase of local resistance caused by interface mismatch and affect the smoke exhaust efficiency.

Linkage with fire damper: the fan must support linkage with "280℃ fused fire damper"-when the flue gas temperature reaches 280℃, the fire damper will automatically close and trigger the fan to stop, so as to prevent the flame from spreading through the pipeline. Please confirm that the fan control module supports this linkage logic when selecting the type.

Airflow direction adaptation: Make clear the "air supply direction" (downstream/countercurrent) of the fans, ensure that it is consistent with the airflow path of the smoke exhaust system, and avoid the reverse direction of smoke exhaust caused by reverse installation (some fans are designed in one direction, and the reverse operation will greatly reduce the wind pressure).

Five, check the manufacturer's qualification and after-sales, to avoid security risks.

Fire-fighting smoke exhaust fans are "fire-fighting products", so it is necessary to choose manufacturers with legal qualifications and after-sales guarantee to avoid purchasing "three no products":

Compulsory Certification (CCCF): Fans that have passed the National Compulsory Product Certification (CCCF) of China must be selected. Products without CCCF certification are strictly prohibited to be used in the fire protection system (they do not conform to the specifications and will be rejected at the time of acceptance).

Technical ability of manufacturers: manufacturers with mature cases (such as similar food factories and large-scale construction projects) are preferred, and on-site installation guidance and debugging services can be required to avoid the performance being affected by improper installation.

After-sales and maintenance: Confirm the after-sales guarantee provided by the manufacturer (for example, the warranty period is ≥1 year, and the life-long maintenance service). Fire fans need to be inspected regularly (for example, cleaning the dust accumulated on the impeller and testing the linkage function every quarter). The maintenance response speed of the manufacturer directly affects the reliability of the system.

Sixth, consider the needs of special scenes and avoid "universal selection"

Some scenes have special requirements and need to be adjusted and selected:

Multi-smoke zone linkage: If the building is divided into multiple smoke prevention zones (such as large shopping malls), it is necessary to select fans (or multi-fans linkage) that support "zone control", and only start the fans in the fire zone in case of fire, so as to reduce energy consumption and ineffective smoke exhaust.

Anticorrosion requirements: Food processing plants (such as pickling workshops and acidic environments), chemical buildings, etc., need to choose "anti-corrosive treatment fans" (such as impellers and casings made of 304/316 stainless steel, or galvanized+anticorrosive coatings) to prevent corrosive gases from damaging the fans.

Space limitation: If the installation space is narrow (such as underground machine room and ceiling), it is necessary to choose "compact fan" (such as thin centrifugal fan and diagonal fan) to reduce the occupied space on the premise of meeting the performance.

summary

The core logic of selecting fire smoke exhaust fan is: "compliance is the premise, performance is the core, scene is the guidance, and compatibility is the guarantee". It is necessary to make clear the smoke exhaust demand (quantity, pressure and temperature) of the building first, then match the type and performance of the fan, check the qualification and pay attention to the compatibility of the system at the same time, and finally ensure that the fan can exhaust smoke stably and efficiently in case of fire, so as to gain time for personnel evacuation and fire fighting and rescue.