Knowledge!Precautions for installation and commissioning of centrifugal fans

1. Before fan installation:

First prepare the materials and tools required for the centrifugal fan device, check all parts of the fan, and check the impeller, casing, main shaft, bearings and other components. If damage is found, repair it and then clean the inside of the bearing box with kerosene.

2. When installing:

(1) On some joint surfaces, in order to avoid corrosion and reduce disassembly difficulties, a layer of grease or engine oil should be applied.

(2) If there are positioning pins on the joint surface, install the pins first and then tighten the bolts.

(3) Check the inside of the casing, impeller, and bearing box to remove fallen and lost objects and other debris.

(4) The connection surfaces between the centrifugal fan and the foundation, and the connection surfaces between the air inlet and the air outlet should comply with natural requirements and should not be forcibly connected, not to mention adding weight to the pipes on each component of the fan.

(5) In order to keep the transmission group from rusting, a certain amount of grease is injected into the transmission box before leaving the factory. Please pay attention to the installation.

3. Device requirements:

(1) According to the direction and scale shown in the drawing, pay special attention to ensuring the radial gap and axial overlap scale between the air inlet and the impeller to ensure the performance and efficiency of the fan.

(2) In order to ensure the level of the main shaft device, the distance between the fan coupling and the motor coupling should meet the requirements: generally 3-5mm, the coaxiality tolerance is 0.05mm, and the end face parallelism tolerance is 0.05mm.

(3) When installing the regulating door, be careful not to install it in the opposite direction to ensure that the air inlet direction is consistent with the impeller rotation direction.

(4) After the fan is installed, turn the impeller to check whether there are any abnormal phenomena such as friction, over-tightening, collision, etc., whether the wiring is correct, whether other safety facilities are complete, whether the rotating part or the direction of the inlet and outlet has been separated, and the trial operation can only be carried out after ensuring safety.

(5) In order to avoid the influence of the pipe weight and thermal expansion on the normal operation of the fan, soft joints made of asbestos, canvas or high-temperature resistant materials should be used when connecting the fan inlet and outlet to the pipe.

(6) Machinery oil should be added to the bearing box, and the oil level should be checked with an oil mark. No other grease or waste oil should be injected.

(7) When installing a centrifugal fan on the floor or platform, the following work should be done: ⑴ The floor or platform where the centrifugal fan is installed should be a cast-in-place reinforced concrete slab with a thickness of not less than 80mm. Cold-rolled steel bars should not be used. If it is equipped with vibration damping data, its flatness requirements are relatively high, and the height difference should be controlled below 2mm to ensure that the vibration damping data is evenly stressed. ⑵The span of factory building beams should not be greater than 6m. ⑶ Cantilever structures are strictly prohibited for floors and platforms. ⑷The horizontal inertial force generated by the centrifugal fan should act in the direction of stronger structural stiffness. ⑸ Ventilators with an interference force greater than 3000n shall not be installed directly on the floor and shall be supported by beams. ⑹ The difference between the interference frequency and the self-frequency of the floor is required to be no less than 30% to avoid resonance and increase the oscillation of the floor structure. ⑺ When the ventilator is installed on data with anti-vibration rubber or anti-vibration spring, the anti-vibration data should be centered on the center of gravity of the entire ventilator. Although the selection of anti-vibration data avoids oscillations in the foundation, there is a slight increase in oscillations in the ventilator itself. Therefore, it is recommended to choose flexible joints made of canvas or rubber.

4. Test run:

(1) When starting the centrifugal fan, you should first close the regulating door, and then gradually open the regulating door after the fan starts working.

(2) Trial operation time: no less than 2 hours for a newly installed unit and no less than half an hour for a maintenance unit. It can be put into use after the trial operation is correct.

(3) Note: The working condition of the induced draft fan is a high temperature of 200°C. In principle, trial operation is not allowed at room temperature. The motor condition should be monitored during a short trial run. If the motor temperature rises too high, it should be stopped immediately.

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