1、 The purpose of ventilation fan
9-12 and 9-26 centrifugal fans are generally used for forging and high-pressure forced ventilation, and can be widely used for conveying materials, conveying air, and gases that are non corrosive, non self igniting, and do not contain viscous substances. The temperature of the medium generally does not exceed 50 ℃ (up to 80 ℃), and the dust and hard particles contained in the medium do not exceed 150mg/m3.
2、 Types of ventilation fans
This ventilation fan is a single suction type, with 13 machine numbers including NO4, 4.5, 5, 5.6, 6.3, 7.1, 8, 9, 10, 11.2, 12.5, 14, and 16.
The ventilation fan can be made in two types: right-handed and left-handed. Looking from one end of the motor, if the impeller rotates clockwise, it is called the right whirlwind, represented by "right"; The counterclockwise rotation is called the left cyclone machine, represented by "left".
The outlet position of the fan is represented by the outlet angle of the casing. Both "left" and "right" can be made into six angles: 0 °, 45 °, 90 °, 135 °, 180 °, and 225 °.
The transmission modes of the fan are Type A (NO4-6.3) and Type D (NO7.1-16).
3、 Structure of ventilation fan
NO4-6.3 is mainly composed of impeller, casing, air inlet, bracket, etc. NO7.1-16 is mainly composed of impeller, casing, air inlet, transmission group, etc.
Impeller: There are 12 blades for the 9-19 type fan and 16 blades for the 9-26 type fan. All belong to the forward curved blade type. The maximum circumferential velocity at the outer edge of the impeller diffuser shall not exceed 140m/S. After the impeller is formed, it undergoes static and dynamic balance correction to ensure smooth operation.
Shell: Welded into a snail shaped shell with ordinary steel plates as a whole.
Air inlet: Made into a convergent streamlined overall structure, fixed to the front cover plate group with bolts.
Transmission group: composed of main shaft, bearing box, coupling, etc. The main shaft is made of high-quality steel, and the bearing box has an overall structure, using rolling bearings and lubricated with bearing grease.
4、 Performance and selection of ventilation fans
The models 9-19 and 9-26 only provide the dimensionless performance table and curve for the NO10 prototype. The dimensionless performance table or curve provided is used to calculate the dimensionless performance of fans above NO10.
Formula for calculating dimensional parameters from dimensionless parameters:

In the K-motor reserve coefficient formula:
When the usage state is in a very standard state, it is necessary to adjust the non-standard η in - internal efficiency
Convert the performance of the state to the performance of the standard state, and then convert it to n-speed (r/min)