1) Purpose
The 3-81 type centrifugal fan can be used for indoor ventilation in general factories and large buildings, transporting air and other non-spontaneous ignition. It is a gas that is harmless to the human body and non-corrosive to steel. B3-81 type fan can be used for ventilation of flammable and volatile gases.
2) Applicable environment
There must be no viscous substances in the gas, the dust and hard particles contained shall not exceed 150 mg/m³, and the gas temperature shall not exceed 80°C.
3) Rotation angle
Viewed from one end of the motor, the impeller rotating clockwise is called a right-hand fan, represented by "right"; the impeller rotating counterclockwise is called a left-hand fan, represented by "left". The outlet position of the fan is expressed by the angle of the air outlet of the casing. 3-81 type fans No.2.8~No.6 are all made in one form when leaving the factory. The user can install them in the required position according to the requirements. There is no need to specify when ordering. No.2.8 air outlet position adjustment range is 0°~225°, the interval is 45°; No. 3.2~No.6 air outlet position adjustment range is 0°~225°, the interval is 22.5°; No.8~No. 12 outlet wind The outlet position adjustment range is 0°~225°, and the interval is 45°; the air outlets of No.16 and No.20 are made into three fixed positions of 0°, 90°, and 180°, which cannot be adjusted. Please indicate this when ordering. There are four fan transmission modes: A, B, C, and D. Among the 3-81 type fans, No. 2.8~No.6 adopt A-type transmission; No.8~No. 12 adopt C and D-type transmission; No.16~No. 20 adopt B-type transmission.
4) Overall structure
Among the 3-81 type fans, No. 2.8~No.6 are mainly composed of impeller, casing, air inlet and other parts with a direct-coupled motor; No. 8~No. 20, in addition to the above parts, also have a transmission part, etc.
① Impeller. It consists of 10 backward-inclined airfoil-shaped blades, a curved front disk and a flat rear disk. It is made of steel plate or cast aluminum alloy and has undergone dynamic and static balance correction. It has good air performance, high efficiency and smooth operation.
②Case. Made into two different forms: No. 2.8 ~ No. 12 casings are made as a whole and cannot be disassembled; No. 16 ~ No. 20 casings are made into three-open forms, except that they are divided into two halves along the central dividing horizontal plane. , the upper part is then divided into two halves vertically along the center line and connected with bolts.
③Air inlet. It is made into a whole and installed on the side of the fan; the cross section parallel to the axial direction is curved, which can allow the gas to enter the impeller smoothly, and The loss is smaller.
④Transmission part. It consists of main shaft, bearing box, rolling bearing, pulley or coupling.
