Low, Medium and High Static Pressure Low Cfm Industrial Exhaust Centrifugal Fans 4-79 4-2X79 Series

PURPOSE
Type 4-79 centrifugal fan can be used as ventilation and air exchange in the rooms of general plants and large buildings or transferring air and other gases which are non-natural, non-explosive, non-volatile, non-harmful for human body and non-corrosion for steels. Type 4-79 centrifugal fan, dust and hard particle content in the gas is not greater than 150mg/m³. The gas temperature shall not exceed 80?. The fan which the performance is similar can also be used.

TYPE
The fan can be made of 2 types of rotation i.e, right and left. Viewing from one end of the motor, it is called as clock-wise fan if the impeller rotates clock-wise, symbolized with “right”, On the contrary, it is called as counter-clock-wise fan if the impeller rotates counter-clockwise, symbolized with “left”.
The outlet position of the fan is expressed with the outlet angle of the casing. ?.3A~6A of type 4-79 fan is manufactured one model when it is ex-works, user shall install it in the required position according to the requirement. The regulating angle of the outlet position is 0°~225°, the distance is 45°. The regulating angle of outlet position for ?.7C~8C is 0°~180°, the distance is 22.5°. The single and double inlet and outlet position for ?.10E~20E is manufactured three models:0°, 90°, 180°, and they can not be adjusted. If you want to order the special model,special outlet angle and non-standard type of fan,our factory can also design and manufacture the type which you wanted,but you must note in detail when purchasing.

STRUCTURE
?3A~6A of Type 4-79 centrifugal fan mainly consist of impeller, casing, air intake and motor etc. ?7C~20E with driving unit except the above structure.
Impeller —It is made of steel plate, and it shall be balanced statically and dynamically,thus it guarantees a smooth operation.?3 and 3.5 impeller consist of 12 blades, ?4 and 4.5 consist of 14 blades,above ?5 consist of 16 blades.
Casing — To be welded into a volute with normal steel plate.it shall be made two kinds of different types, among them: ?3~12 casing is made in integral type, it can not be disintegrated.?14~20 is manufactured in two-opened model, it is divided into two halves along the split surface, and connect then with bolts.
Inlet — the inlet is manufactured as an integral type, the inlet is generally fixed on the side of the fan, the section which is parallel to the shaft is curved forms and gas is allowed into the impeller smoothly with a little loss.
Driving unit — It consists of shaft, bearing box, rolling bearing, belt pulley.

PERFORMANCE AND SELECTION
(1)The performance of fan:the performance of fan is expressed with flow rate,total pressure, shaft speed,shaft power and power parameters. The certain relationship is existed among each parameter. The relationship is listed as follow:

Converting formula for changing density, speed n:

Converting formula for changing speed n, atmosphere Pa, and gas temperature t:

Where:

Q — flow (m³/h)                                  — density (kg/m³)
p — total pressure(Pa)                           n — speed(r/min)
P — power(kW)                                     t — temperature(?)
? — efficiency(%)                                  Pa — atmosphere(Pa)

With footnote‘2’means known performance parameter, with footnote‘1’means unknown performance parameter.
The fan performance indicate the performance of delivered gas under standard state. The standard state means: atmosphere Pa = 101325 Pa, atmosphere temperature t=20?, relative humidity X=50%, air density ?=1.2 kg/m³.

The required power is calculated with the formula below:

Where:

Q — flow (m³/h)                        ?_m — mechanical efficiency(%)
p— total pressure(Pa)                K — Storing factor of motor

?— efficiency(%)

(2)Selection of fan:the fan performance indicates the performance of the delivered gas under the standard state. When the operation condition is under the non- standard state, the performance of non- standard state must be converted into standard performance,then select fan according to the performance table.

Mechanical efficiency

Storing factor of motor

PURCHASE INFORMATION
When purchasing,indicate the fan size, flow rate, pressure,discharge angle, rotation direction and the motor model, power and speed etc.