4-79 proof centrifugal fan from the motor side of the face, the impeller rotates clockwise, called D-blower to "right" means; counterclockwise rotation of the impeller, called L-blower to "left". B4-79-type centrifugal fan outlet position №3 ~ 6 0 to 225 degrees, the interval is 45 degrees, the transmission mode for the A-type transmission; №7 ~ 20 outlet location for 0,90, 180 degrees, №7 ~ Transmission 12 is C type or E-type transmission, transmission mode №14 ~ 20 for the E-type transmission; №2x5 ~ 2x20 outlet location is 0,90, 180 degrees, the transmission mode for the E-type transmission. B4-79-type centrifugal fan №3 ~ 6 fans are assigned by the impeller, housing, air inlet and other units which consists of direct-coupled motor; №7 ~ 20 and №2 × 5 ~ 2 × 20 addition to the above section, but also There are transmission parts and so on. 1) impeller by 16 sheet backward arc type blade, curved front plate and the plate after plate components. With a cast aluminum alloy, and by the dynamic and static balance correction, air good performance, high efficiency and smooth operation. 2) housing made of two different types. №3 ~ 12 and №2 × 5 ~ 2 × 12 cabinet as a whole, can not be disassembled. Chassis system №14 ~ 20 and №2 × 14 ~ 2 × 20 two open into style, into two halves along the horizontal carve, bolted. 3) inlet made whole, mounted on the fan side, parallel to the axial cross-section shape of the curve, the gas can smoothly enter the impeller, and minor damage.