Centrifugal fan (hereinafter referred to as fan) is a low, medium and high pressure fan with a wide range of applications, flat pressure curve, easy installation and maintenance, and low cost. In today's world of numerous fans, it is mainly used for ventilation of general factories, warehouses, high-rise buildings, subways and other large buildings, and often appears in major and critical occasions such as Beijing subway, where people are inundated and their lives are at stake. It can both output and input gas, but the gas to be transported must be air or other non-spontaneous combustion.

Gas that is non-volatile, non-explosive, non-corrosive to steel, and harmless to the human body. The gas must not contain sticky substances, and the proportion of dust and hard particles contained in the transported gas must not exceed 150mg/m3, and the temperature of the transported gas must not exceed 80C.

B centrifugal fan, also known as explosion-proof centrifugal fan (indicated by "B"), can transport flammable, explosive and volatile gases. Its air performance, external dimensions, foundation dimensions and internal structure are exactly the same as those of LF-47 of the same machine number, but the power must be changed to explosion-proof motor, and the impeller should be made of aluminum to prevent the impeller from rubbing against the casing and catching fire due to the tilt of the impeller. The switch should be explosion-proof or away from the explosive point to prevent the switch from igniting and detonating. All wires in the explosive area are not allowed to have joints to prevent "false connection" from catching fire, and the wires should be installed in iron pipes.

Centrifugal fans are often used in mines, tunnels, chemical industries and other occasions.

Centrifugal fans can transport gases that are corrosive to steel, harmful to the human body and toxic. All parts of this fan that may come into contact with the transported gas, such as: casing, impeller, air inlet, air outlet, etc., should be made of corrosion-resistant materials, such as stainless steel, fiberglass and other corrosion-resistant materials. Its air performance, external dimensions, foundation dimensions, internal structure, power, etc. It is often used in important occasions such as chemical plants, galvanizing plants, and fertilizer plants.

Type

In general, centrifugal fans have more than 30 machine numbers and more than 100 varieties, including 2.8A, 3.2A, 3.6A, 4A, 4.5A, 5.6A, 6A, 6C, 6D, 8C, 8D, 10C, 10D, 12D, 16B, 20D~30D, 20F~30F. Any transmission of any machine number can be made into "left" or "right" rotation types. Looking at the impeller from one end of the motor, those that rotate clockwise are called "right-hand fans" and are represented by "right", and those that rotate clockwise are called "left-hand fans" and are represented by "left".

The air outlet position of the fan is indicated by the air outlet angle of the casing. The user unit can install it to the required position according to the requirements. It is not necessary to specify it when ordering.

Special attention: ①The adjustment range of the №2.8A air outlet is 0°～225°, with an interval of 45°;

②The adjustment range of the №3.2A～6A, 6C, 6D air outlet is 0°～225°, with an interval of 22.5°;

③The adjustment range of the №8D～10C, D air outlet is 0°～180°, with an interval of 45°;

④The adjustment range of the №12C, D air outlet is 0°～180°, with an interval of 15°;

⑤The №l6B, 20D air outlet angles are made into three "fixed" 0°, 90°, and 180°, which cannot be adjusted. Please indicate which one to use when ordering.

⑥The above air outlet angles are customary practices in the fan industry. If these practices cannot meet your specific use environment and conditions, our factory can make them for you to satisfy you. When this happens, the installation dimension table at the back of this manual may change. Please pay attention.

There are six transmission modes for fans: A, B, C, D, E, and F:

A means that the fan shaft disc is installed on the motor shaft extension through a keyway, that is, the motor is directly inserted;

B means a cantilever support device, belt drive, and the pulley is between the two bearings;

C means a cantilever support device, belt drive, but the pulley is on the outside of the bearing;

D means a cantilever support device, connected and driven by a coupling.

E means a double support device, belt drive, but the pulley is on the outside of the bearing.

F means a double support device, connected and driven by a coupling.

These transmission modes can generally meet the user's use requirements. If they cannot meet your requirements, our factory has the strength to design and produce fans that satisfy you.

Conclusion Structure

The fan is generally mainly composed of an impeller, a casing, an air inlet and a transmission part, but No. 2.8~6A is an A-type transmission without a transmission group.

Impeller 1 It is the core component of the fan. Its material and profile determine the wind pressure and air volume of a fan. Energy consumption, noise and life. This fan consists of ten backward-inclined wing-shaped blades, a curved wheel cover and a flat rear disc. It is made of ordinary steel plates, 16 manganese steel, stainless steel or fiberglass according to different uses and media. After dynamic and static balance correction and overspeed operation experiments, it runs smoothly and reliably, and has good air performance.

Casing 1 The casing is made into two different types, among which: the casing of No. 2.8~12 is made into an integral part and cannot be disassembled. The casing of No. 16~30 is made into an upper and lower split type along the horizontal direction, and the upper part is divided into two halves vertically along the center line and connected with bolts, mainly for the convenience of disassembly, maintenance and movement. The specific material is welded from ordinary iron plates, stainless steel, or fiberglass according to the purpose of the fan. Of course, the process, cost and construction period are also different.

Air inlet - The air inlet is made into an integral structure. Its cross-section parallel to the axial direction is a curved shape, which facilitates the smooth entry of gas into the impeller with less loss. The air inlet is usually fixed to one side of the fan with bolts. If the radial and axial clearance between the air inlet and the impeller is too small, it will cause friction if you are not careful. If it is too large, it will cause air leakage and affect efficiency. Please ensure the design size.

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

Performance

The performance of the fan is usually expressed by parameters such as flow rate, total pressure, main shaft speed, shaft power, efficiency, etc. There is a certain conversion relationship between these parameters, and the relationship can be expressed by performance curves, mathematical formulas or tables;

If Q is set as flow rate        m3/h;               H is total pressure      Pa;

N is shaft power      kW;                η is total pressure efficiency

ηm is mechanical efficiency   ％;                     r is specific gravity        kg/ m3;

n is main shaft speed    r／min;                t is temperature        ℃