English
The installation of large exhaust fans (industrial exhaust fans, negative pressure fans, etc.) is a comprehensive project involving structural safety, electrical specifications, and ventilation effects. To ensure efficient, safe, and long-lasting operation of equipment, the following are systematic technical points for the installation of large exhaust fans:
1、 Survey and selection confirmation before installation
Wall structure load-bearing evaluation: Before installation, it is necessary to confirm the material of the installed wall (brick concrete, concrete, light steel keel or color steel plate). For non concrete walls, additional structural reinforcement treatment is required, such as embedding steel frames or adding angle steel supports, to prevent wall cracking or collapse caused by vibration during fan operation.
Installation environment matching: Confirm the clearance size of the installation location, ensure that the fan blades are kept at a safe distance of at least 1.5 times the diameter of the fan from surrounding obstacles (such as pipes and lighting) when the fan is turned on, and avoid air vortex interference.
Electrical capacity pre check: Large exhaust fans are mostly powered by three-phase 380V power supply. It is necessary to verify in advance whether the on-site cable diameter, circuit breaker capacity, and overload protection device match the rated current of the motor. It is strictly prohibited to temporarily overlap in the case of insufficient power lines.
2、 Basic bracket and fixing process
Anti corrosion treatment of steel brackets: If external or triangular brackets are used for installation, the bracket steel needs to be hot-dip galvanized or coated with anti rust paint. The welding area must be polished flat and coated with anti rust paint to prevent rusting caused by rain and breakage.
Leveling calibration: When installing the base, a high-precision level must be used for bi-directional leveling. The horizontal deviation should be controlled within 1/1000, otherwise long-term operation will cause unilateral force on the bearing, accelerate wear, and produce abnormal noise.
Chemical anchor bolts or through wall bolts for fixation: It is strictly prohibited to use expansion bolts to directly hit hollow bricks. Heavy duty fans should be fixed using chemical anchor bolts or through bolts with large washers, and the tightening torque should reach the design standard value. Additionally, shock-absorbing rubber pads should be installed on the contact surface between the bolts and the wall.
3、 Shock absorption and noise reduction treatment
Damping shock absorber installation: A dedicated damping spring shock absorber or rubber shear shock absorber pad must be installed between the fan base and the steel structure bracket. This can effectively isolate structural sound transmission and prevent low-frequency noise caused by fan vibration transmitted along the building structure.
Flexible soft connection: If the fan is connected to an external air duct, fireproof canvas or silicon titanium soft connection must be installed at the inlet and outlet of the fan, with a length of 150-250mm. This can compensate for installation errors and cut off rigid vibration transmission.
4、 Electrical Connection and Safety Protection
Grounding and lightning protection: The motor casing and metal bracket must be equipped with independent grounding terminals, and the grounding resistance should not exceed 4 Ω. If installed at high places such as roofs, lightning protection equipotential connection should be considered.
Line protection pipe laying: The power line must be fitted with a metal hose or PVC flame-retardant pipe, and the interface must be connected with a locking buckle to prevent rodent bites or wear on the insulation layer. No joints are allowed in the middle. If wiring is necessary, a junction box must be set up.
Phase sequence verification and overload protection: After wiring, it is necessary to jog and test the direction of rotation to ensure that the direction of fan blade rotation is consistent with the arrow mark (reversing will cause a sudden drop in air volume). The setting value of the thermal relay should be set at 1.05~1.1 times the rated current on the motor nameplate to prevent phase loss or overload from burning out the motor.
5、 Safety protection net and sealing treatment
Double protection net: High density steel wire protection net should be installed on the inside of the blinds, with a mesh diameter not exceeding 20mm, to prevent birds from entering by mistake or personnel from touching their fingers. The protective net must be independently fixed and cannot rely solely on the fan blade cover for load-bearing.
Gap sealing and gluing: The gap between the fan frame and the wall opening (usually reserved for 30-50mm) needs to be filled with polyurethane foam agent and treated with weather resistant sealant on the outside for waterproofing. The inner side is sealed with structural adhesive to prevent rainwater backflow and air leakage.
6、 Debugging and operational testing after installation
Static inspection: Manually rotate the fan blades to check for any jamming or friction sounds, and confirm that the gap between the fan blades and the collector is uniform (usually 3-5mm on one side).
No load test run: After power on, run the motor without load for 30 minutes, monitor whether the three-phase current is balanced (with an error of no more than 5%), and measure the temperature rise of the motor casing. Touch the shock absorber and anchor bolts with your hands to check for signs of looseness.
Dynamic balance retest: If severe shaking is found during operation, the machine should be stopped immediately. This usually indicates that there is a dynamic balance deviation in the fan blades, and the manufacturer should be contacted for on-site dynamic balance correction. It is strictly prohibited to operate with defects.
Shutter opening test: For negative pressure fans, it is necessary to observe whether the louvers can fully open without jamming under the action of wind; Can it be closed naturally by gravity after shutdown to achieve dust and rain prevention effects.
7、 Additional points for special environments
High dust environment: It is recommended to install an automatic lubrication device and shorten the initial oil change cycle (it is recommended to replace the gear oil after 200 hours of operation).
Damp/Corrosive Environment: All fasteners must be upgraded to 304 stainless steel material, and the motor protection level must reach IP55 or above.
Roof installation: A rainproof cap should be made and the motor position should be raised to prevent water from soaking the motor feet.
