purpose
The main use of 4-72 type centrifugal fan for indoor ventilation in general factories and large buildings or the air transport and other non flammable, explosive, volatile, the human body harmless gas corrosion of steel; B4-72 type centrifugal fan can discharge flammable, volatile gases; F4-72 centrifugal fan is mainly used for conveying corrosive gases. However, 4-72, B4-72, F4-72 centrifugal fan conveying gas are not allowed to contain viscous substances, containing dust and hard particles are not more than 150mg/m3, the gas temperature shall not exceed 80 degrees C.
The performance of B4-72 type fan with optional part and foundation of size and 472 type, can be selected according to the sample. The fan structure is basically the same with the 4-72 type motor, No. 2.8A - 6A with B35 type flange and foot, No. 6 - 12C, D and Y series motor selection table corresponding to the YB series, the installation type is B3.
F4-72 type centrifugal fan is made of stainless steel, glass fiber reinforced plastic or other corrosion resistant materials, the performance and the size of the foundation are the same as that of the 4-72 centrifugal fan.
4-72 type centrifugal fan fan is first used in China, but also the most common fan, from high-rise buildings and underground railways, boiler blast to plant ventilation, from the northern border to the South China Sea, from the western plateau to the east side down, 4-72 fans everywhere.
type
From one end of the motor face, where the impeller clockwise rotation are known as "right whirlwind machine" to "right", otherwise, it is called "left whirlwind machine" to "left".
The fan outlet position in said casing outlet angle, 4-72 fan no 2.8 - 6 in the factory are made of a type, the use of units according to requirements to install into the desired position, in order to indicate. The No. 2.8 outlet position adjustment range is 0 degrees, 225 degrees, the interval is 22.5 degrees; No. 8 - 12 outlet adjustment range is 0 degrees, 225 degrees interval is 45 degrees; No. 16, the 20 air outlet angle made of three kinds of fixed 0 degrees, 90 degrees, 180 degrees, can not be adjusted, specify when ordering.
A, B, C, D four kinds of transmission mode of fan: 4-72 fan, No. 2.8 - 5 by A transmission, No. 6 is A type transmission and C transmission, No. 8-12 by C, D two kinds of transmission mode, No. 16-20 using B type transmission.
If the machine number, transmission mode, outlet angle can not meet the needs of your production, our factory has the ability to transform or design for you until you are satisfied.
structure
4-72 type centrifugal fan No. 2.8 - 6A is mainly composed of impeller, casing, air inlet, motor and other components. No. 6C and No. 8 - 20 in addition to the structure, and the transmission part.
The impeller consists of 10 inclined - turbine airfoil blade, curved and flat wheel cover plate, steel (aluminum alloy B4-72) produced by the static and dynamic balance correction and overdrive experiment, high efficiency, stable and reliable operation, good performance of air.
A - made of two different types, including: No. 2.8 - 12 chassis as a whole, they cannot be separated. No. 16 - 20 housing made of three open, in addition to the level divided into two parts, the upper part along the vertical center line is divided into two halves, connected by bolts, so that the installation and maintenance into or out of the impeller.
The air inlet is made into an integral structure which is arranged on one side of the fan, and the cross section parallel to the axial direction is a curved shape.
Transmission - composed of spindle, bearing box, rolling bearing, pulley or coupling.
Performance and selection

The sample was given No. 10 prototype dimensionless performance table and dimensionless performance curve, a number of other machine dimensional performance parameters can be deduced

Table 1 4-72 No. 10 prototype dimensionless performance table
123456
Phi
Only
Only D
Lambda
Eta in 0.1884
Zero point four five eight
Zero point zero three three five
Zero point zero nine nine five
0.867 0.2051
Zero point four five two
Zero point zero three nine seven
Zero point one zero four five
0.887 0.2218
Zero point four three four
Zero point zero four six five
Zero point one zero eight two
0.89 0.2361
Zero point four one three
Zero point zero five two eight
Zero point one one zero six
0.882 0.25
Zero point three nine
Zero point five nine four
Zero point one one two six
0.866 0.2637
Zero point three six three
Zero point zero six six three
Zero point one one three seven
Zero point eight four two
The dimensionless parameters are calculated as follows:
Q=900 D22U2 (m3/h) P= PI Phi Rho 1U22 /Kp (Pa)
Kp= Nin= (KW)
Nre= (KW)
In type:
Q flow (m3/h)
Kp full compression coefficient
P total pressure (Pa)
Nin - internal power (KW)
Nre - required power (KW)
D2 - impeller outer diameter (m)
U2 - impeller blade edge line velocity (m/s)
P 1 - air density (kg/m3)
The mechanical efficiency of M
K - motor reserve factor
Fan performance generally refers to the performance of air transportation in the standard state, the so-called standard state refers to the atmospheric pressure Pa=101325Pa, atmospheric temperature of t=20 DEG C and relative humidity X=50%, air density =1.2kg/m3, when using the state for non standard state, it must be the performance of non standard state properties converted to standard state, then the look-up table select the conversion formula is as follows:
(m3/h) (Pa)
In0= in (KW).
There are 0 footnotes in the form of the standard state without footnote 0 for the use of state
Table 2 mechanical efficiency
Drive motor direct coupling triangle belt
ETA m 10.98 0.95
Table 3 Motor reserve factor
Shaft power KW >0.5-1 >1-2 >2-5 >5 <0.5
K 1.5 1.3 1.2 1.4 1.15
Fan operation, often happened or insufficient flow phenomenon, the main reason is because the pipeline resistance when flying in or fan area and other reasons; if in use process, after a long time to gradually reduce or decrease suddenly in a short period of time, is the network congestion.
In the new installation of the fan, the flow is too large or insufficient phenomenon, the main reasons for this phenomenon are the following two points:
(1) the difference between the actual value and the calculated value is too large. General wind characteristic equation: P=KQ2 can be seen, such as the actual value of K is less than the calculation of K, the flow increases, otherwise, the flow reduction. See Figure 2
(2) the selection of the fan does not take into account the full pressure deviation of the impact of P, when the actual fan pressure is a positive deviation, the flow increases, the negative deviation, the flow is reduced.
If the flow is too large or too long after the new installation of the fan is started or when in use, one of the following methods can be used to eliminate: