（1） Purpose

4-72-12 centrifugal fan (hereinafter referred to as fan) can be used for general ventilation, and its service conditions are as follows:

1. Application site: as indoor ventilation of general factories and large buildings, it can be used as both input gas and output gas.  

2. Type of gas transported: air and other gases that are non self igniting, harmless to human body, and non corrosive to steel materials.  

3. Impurities in the gas: there shall be no viscous substances in the gas, and the contained dust and hard particles shall not be more than 150 mg/m3.  

4. Gas temperature: no more than 80 ℃. B4-72-12 explosion-proof fan has № 2.8-12, 9 machine numbers in total. Its air performance and shape structure are identical to those of the 4-72-12 type with the same machine number. Except that the impeller material is ZL104 aluminum and the motor is explosion-proof, it can be selected according to the performance and selection table of the 4-72-12 type fan. F4-72-12 anti-corrosion fan can be used for ventilation of corrosive and non self combustible gases. The temperature of transported gas shall not exceed 60 ℃, and the relative humidity shall not exceed 98%. BF4-72-12 explosion-proof and anti-corrosion fan can be used for ventilation of corrosive, flammable and volatile gases. The temperature of transported gas shall not exceed 60 ℃, and the relative humidity shall not exceed 98%. F4-72-12 and BF4-72-12 fans are different from 4-72-12 fans in the above points. The aerodynamic performance and installation dimensions can be selected according to the performance and selection table of 4-72-12 fans.  

（2） Features  

F4-72-12 anti-corrosion fan can be made into two forms according to different use conditions of users: A is Ⅰ F4-72-12, made of all glass fiber reinforced plastic, B is Ⅲ F4-72-12, and SZ-1 inorganic salt ambient curing anti-corrosion coating is sprayed on the surface of ordinary 4-72-12 fan. BF4-72-12 explosion-proof and anti-corrosion fan can be made into two forms according to different use conditions of users: A is type I BF4-72-12, which is made of full glass fiber reinforced plastic, the impeller is treated with anti-static coating, and the explosion-proof motor is used, B is type III BF4-72-12. The exposed parts of the fan are sprayed with SZ-1 inorganic salt curing anti-corrosion coating at room temperature. In addition to spraying, the impeller is also made of iron aluminum structure, Explosion proof motor is adopted. Ⅰ F4-72-12, Ⅰ BF4-72-12 all glass fiber reinforced plastic fan is made of epoxy glass fiber reinforced plastic with superior ratio, and has the following characteristics:

1. The machine structure has high mechanical strength and light weight. The mechanical strength of glass fiber reinforced plastic is much higher than that of plastic, which is basically the same as that of steel, while its weight is only about one-third.  

2. High efficiency. The efficiency of FRP fan is similar to that of steel fan.  

3. Stable operation and low noise. The fan impeller also adopts wing type blades, which improves the aerodynamic curve and reduces the resistance loss. The impeller is durable, stable and low noise.  

4. Perfect structure and good quality.

In order to improve the structure of 4-72 FRP fan and ensure the quality, we have taken the following measures during manufacturing:

(1) According to the size of the machine number, different reinforcement measures shall be taken for the manufacture of the impeller.  

(2) After the production of each fan, it shall be carefully checked, subject to precise dynamic balance correction and overspeed test.  

(3) Be responsible for the matching of fan accessories according to the requirements of the user.

5. All glass fiber reinforced plastic fan can discharge acid, alkali, salt fog gas and various corrosive gases of certain concentration.

The Ⅲ F4-72-12 fan sprayed with SZ-1 inorganic salt room temperature curing anti-corrosion coating has the following characteristics:

(1) Each performance index is completely the same as that of ordinary 4-72 fan.  

(2) It can discharge corrosive gases such as water vapor and salt spray, and is suitable for working environments such as seawater corrosion.  

（3） Fan type  

The fan can be divided into two types: right rotation and left rotation. When viewed from one end of the motor, the impeller rotates clockwise, which is called the right cyclone. When it rotates in the right direction, it rotates counterclockwise, which is called the left cyclone. When it rotates in the left direction, it is called the left cyclone. The outlet position of the fan is indicated by the outlet angle of the casing. The 4-72-12 fan produced by our factory can provide six angles of 0 °, 45 °, 90 °, 135 °, 180 ° and 225 °. № 2.8-5 adopts A-type transmission; № 6 adopts A-type transmission, C-type transmission and D-type transmission, and C and D are supported by rolling bearings; № 8-12 is supported by rolling bearings, which is divided into C-type transmission and D-type transmission; № 16-20 is supported by rolling bearings and is driven by type B.  

（4） Structure of fan  

The № 2.8-6A fan in the 4-72-12 fan is mainly composed of impeller, casing, air inlet and other components and supporting motor. № 6C and D-20B have not only the above components, but also the drive set.  

1. The impeller is composed of ten backward inclined airfoil blades, curved front disk and flat rear disk. All are made of steel plate and calibrated by static and dynamic balance, with good aerodynamic performance, high efficiency and smooth operation.  

2. The casing is made into two different types. № 2.8-12 is an integral part and cannot be disassembled. № 16-20 casing is made into three open type. In addition to being divided into two halves along the horizontal plane of the central split, the upper half is vertically divided into two halves along the central line and connected with bolts.  

3. The air inlet is made into a whole and installed on the side of the fan. The section parallel to the axial direction is in a curve shape, which can make the gas enter the impeller smoothly with less loss.  

4. The transmission part consists of the main shaft, bearing box, rolling bearing, pulley or coupling.  

（5） Ordering Instructions  

1. Scope of supply: Type A: one fan, one supporting motor, four sets of anchor bolts for motor. C. Type D and B: one fan, one supporting motor, four sets of anchor bolts for the casing group, four sets of anchor bolts for the box, and four sets of anchor bolts for the slide rail (eight sets).  

2. Ordering: the fan model, number, speed, air volume, total pressure, air outlet angle, rotation direction, motor model and power specification shall be indicated.  

3. If the user has special requirements, please contact the sales department of the factory when ordering, and the factory provides technical consultation. Special requirements must be stated in the contract