1. Usage 4-72 typeCentrifugal ventilation fanIt can be used for indoor ventilation and air exchange in general factories and large buildings. Transport air and other non self igniting, harmless to human health, and non corrosive gases to steel. The B4-72 fan can be used for ventilation and exchange of flammable and volatile gases. There shall be no viscous substances, dust or hard particles in the gas, with a concentration not exceeding 150mg/m3. The gas temperature shall not exceed 80 ℃.
The performance, selected components, and foundation dimensions of B4-72 fan are consistent with those of 4-72 fan, and can be selected according to its sample. The structure of the fan is basically the same as that of the 4-72 type. The No2.8-6A adopts the B35 type motor with flange and foot, while the No.6-12C and D motors use the YB series corresponding to the Y series in this table, and the installation form is B3.
The F4-72 fan is made of stainless steel and fiberglass material for transporting corrosive gases, and its performance and foundation size are the same as the 4-72 type.

2. When viewed from the side of the electric motor, if the wheel rotates clockwise, it is called a right cyclone machine, represented by "right"; if the impeller rotates counterclockwise, it is called a left cyclone machine, represented by "left".
The outlet position of the fan is represented by the angle of the air outlet of the casing. The 4-72 type fan No. 2.8-6 is made in N different forms when it leaves the factory, and the user unit installs it in the required position according to the requirements. When ordering, it is not necessary to specify that the adjustment range of the No. 2.8 air outlet position is 0 ° -225 °; The interval is 45 degrees. NO.3.2-6 The adjustment range of the air outlet position is 0 ° -225 °, with an interval of 22.5 °. NO.3.2-6 The adjustment range of the air outlet position is 0 ° -225 °, with an interval of 45 °. NO.16、 There are three fixed positions for the 20 air outlets: 0 °, 90 °, and 180 °, which cannot be adjusted and must be specified when ordering.
There are four transmission modes for fans: A, B, C, and D In the 4-72 type fan, NO.2.8-6 adopts A-type transmission, NO.8-12 adopts C-type and D-type transmission, and NO.16-20 adopts B-type transmission.

3. The structural characteristics of the 4-72 type fan, NO.28-6, are mainly composed of impellers, casings, inlet air, and other parts matched with direct connected motors. NO.8-20 has not only the above-mentioned parts, but also transmission parts, etc.
(1) The impeller consists of 10 aft inclined blade types, a curved front plate, and a flat rear plate. Made of copper plate or cast aluminum alloy, and calibrated for dynamic and static balance, it has good air performance, high efficiency, and smooth operation.
(2) The casing is made in two different types. The chassis of NO.2.8-12 is made as a whole and cannot be disassembled. The chassis of NO.1-20 is made as a three open type, which is divided into two halves along the horizontal plane of the center, and the upper half is vertically divided into two halves along the centerline, connected by screws.
(3) The air inlet is made as a whole and installed on the side of the fan. The cross-section parallel to the axial direction is curved, which allows gas to enter the impeller smoothly with minimal loss.
(4) The transmission part consists of a main shaft, bearing housing, rolling bearings, pulleys or couplings.

Type 4-72Centrifugal ventilation fanPerformance parameter table