The 4-72 centrifugal fan can be used for indoor ventilation and air exchange in general factories and large buildings, conveying air and other unnatural, harmless, and non corrosive gases to steel. The B4-72 fan can transport flammable and volatile gases, but the temperature must not exceed 80 ℃.
The performance, selected components, and foundation dimensions of the B4-72 fan are consistent with those of the 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 motors numbered 2.8-6A adopt the B35 type with flanges and feet, while the motors numbered 6-12C and D use the YB series corresponding to the Y series in this table, and the installation type is B3.
When leaving the factory, models No. 2.8 to No. 6 are all made into one type, and the user unit installs them in the required position according to requirements. There is no need to specify when ordering. The adjustment range of the No. 2.8 air outlet position is 0 ° to 225 °, with an interval of 45 °. The adjustment range for the position of air outlets No. 3.2-6 is 0 ° to 225 °, with an interval of 22.5 °. The adjustment range for the position of air outlets No. 8-12 is 0 ° to 225 °, with an interval of 45 °. The positions of air outlets No.16 and No.20 are fixed in three types: 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, A type transmission is used for No. 2.8-6, C and D type transmission are used for No. 8-12, and B type transmission is used for No. 16-20.

The detailed performance parameters of this product are as follows: