What should be paid attention to in the installation and maintenance of fire smoke exhaust fan?

The installation and maintenance of fire smoke exhaust fan is directly related to its reliability and effectiveness in the event of fire, and it must strictly follow the requirements of the code. The following are the key points to pay attention to during installation and maintenance:

First, the installation considerations

1. Preparation before installation

Equipment inspection: check whether the model and specifications of the fan meet the design requirements, and check whether the appearance of the fan is damaged (such as deformation of the impeller, cracks in the casing, etc.), and whether the gap between the impeller and the casing is uniform (generally not more than 0.5mm) to avoid failure caused by improper transportation or storage.

Confirmation of installation environment: confirm that the installation location meets the requirements of design drawings, ensure that there are no obstructions (such as pipes and beams) around, ensure smooth airflow at the air inlet and outlet, and avoid the reduction of smoke exhaust efficiency due to narrow space.

Foundation and support: the fan foundation should be flat and firm, and the bearing capacity should meet the equipment weight requirements; Brackets shall be welded with angle steel or channel steel, and reliably connected with the building structure (such as embedded steel plates or expansion bolts), and shall be rustproof (painted with antirust paint and topcoat).

2. Installation process specification

Fan positioning:

The fan shall be installed horizontally, and the error shall not exceed 1‰, so as to avoid excessive vibration or impeller wear during operation due to inclination.

The air outlet of the smoke exhaust fan should face a safe area (such as outdoor or special smoke exhaust shaft) to avoid the backflow of smoke into the room; If it is installed in the ceiling, it is necessary to reserve enough maintenance space (generally not less than the fan size+500mm).

Pipe connection:

The connection between the fan and the air duct should adopt flexible short tubes (such as fire-proof canvas) with a length of 150-300mm to reduce vibration transmission; The flexible short pipe shall not be tight, so as not to affect the operation of the fan.

The interface between air duct and fan should be sealed tightly to avoid air leakage (sealant or gasket can be used); The smoke exhaust duct shall be made of incombustible materials (such as galvanized steel plate), and the wind speed shall not exceed 20m/s (metal duct) or 15m/s (non-metal duct).

Electrical installation:

The wiring of the motor shall conform to the electrical specifications, and the terminal shall be firm and well insulated, and the grounding resistance shall not be greater than 4Ω.

The fan should be equipped with an independent power supply circuit and linked with the fire control system (for example, it can be started automatically through the fire alarm controller, and at the same time, it has manual start-stop function) to ensure that it can be started quickly in case of fire.

Install overload and short-circuit protection devices to avoid motor burning due to failure.

Fire prevention measures:

When the fan is installed on the firewall or the floor, a fireproof plug (such as fireproof rock wool+fireproof sealant) should be set at the wall/floor penetration position to prevent the fire from spreading.

If the fan is located on the branch pipe of the smoke exhaust system, it is necessary to install a smoke exhaust fire damper at the entrance of the fan (when the smoke temperature reaches 280℃, it will be automatically closed and the fan will be stopped simultaneously).

3. Debugging after installation

Trial operation: After installation, conduct continuous trial operation for at least 2 hours, and check whether the fan runs smoothly (vibration speed ≤6.3mm/s), whether there is abnormal noise ≤85dB, and whether the impeller turns correctly (consistent with the direction marked on the casing).

Performance test: use anemometer, pressure gauge and other tools to check whether the smoke exhaust volume and wind pressure meet the design requirements; Test whether the linkage functions (such as manual/automatic start, linkage stop with fire damper) are normal.

Second, the maintenance precautions

1. Daily inspection (weekly/monthly)

Visual inspection: check whether the fan casing and impeller are deformed and corroded, whether the connecting bolts are loose, and whether the air duct interface leaks air.

Electrical inspection: check whether the power line and control line are aging or damaged, whether the terminal is fastened and whether the grounding is reliable; Test the manual/automatic start function to ensure that the buttons and indicator lights are normal.

Environmental cleaning: remove impurities (such as dust, cobwebs, leaves, etc.) at the air inlet and outlet of the fan to avoid blocking the airflow; If it is installed in a humid environment (such as an underground garage), it is necessary to check whether the moisture-proof measures of the motor are in good condition.

2. Regular maintenance (semi-annual/annual)

Mechanical part:

Check the rotating parts such as impellers and bearings. If excessive dust is found on the impellers, clean them with a soft cloth after power failure (to avoid impeller imbalance). If the bearing has abnormal sound or the temperature rise is too high (exceeding the ambient temperature by 40℃), it is necessary to replace the lubricating oil (grease) or bearing.

Check the fan driven by the belt: the belt tightness should be moderate (it is advisable to press the middle of the belt to sink by 10-15mm), and replace it in time if there is any crack or aging, and the alignment error of the pulley should not exceed 1 mm.

Electrical part:

Use a multimeter to detect the insulation resistance of the motor (insulation resistance between phases and ground shall be ≥0.5MΩ). If it is lower than the standard, check for damp or winding failure.

Check the linkage logic of smoke exhaust fire damper and fan: manually close the fire damper and observe whether the fan stops immediately; Use a temperature controller to test whether the fire damper automatically closes and stops the fan at 280℃.

Performance retest: Test the exhaust volume and wind pressure of the fan every year, and compare it with the design value. If the deviation exceeds 10%, it is necessary to check the problems such as pipeline blockage and impeller damage.

3. Special case handling

Post-fire inspection: after the fire, whether the fan is started or not, it is necessary to conduct a comprehensive inspection: whether the impeller and casing are deformed at high temperature, whether the motor winding is burned, whether the circuit is blown, and replace the damaged parts if necessary.

Long-term maintenance: If the fan does not run for a long time (such as seasonal buildings), it needs to be electrified once a month (30 minutes each time) to prevent the motor from getting wet; Clean up the dust on the surface before stopping the machine, and do a good job of moisture-proof and dust-proof protection.

4. Maintain records

Establish a complete maintenance file to record the contents of each inspection and maintenance (such as replaced parts, test data, failure reasons, etc.), so as to facilitate traceability and predict the service life of the equipment.

summary

The installation of fire-fighting smoke exhaust fans should strictly follow the Technical Standard for Smoke Prevention and Exhaust System in Buildings (GB 51251) and other specifications to ensure "correct installation and reliable linkage"; Maintenance needs to adhere to the principle of "prevention first", and through regular inspection and professional maintenance, the equipment can be "pulled out and used" in case of fire, so as to really play the key role of smoke exhaust to save people.