commercial exhaust fan for drop ceiling

commercial exhaust fan for drop ceiling

4-82 type centrifugal fan is a new product developed by our company according to user requirements, which can meet special demand of air-conditioners for large air flow and low pressure.
Product description

Ⅰ Purpose of fan
4-82 type centrifugal fan is a new product developed by our company according to user requirements, which can meet special demand of air-conditioners for large air flow and low pressure. This fan is compact in structure, high in efficiency, low in noise, flat in curve and wide-ranged in performance.
4-82 type centrifugal fans are all driven by double-suction belt and they are applicable to ventilation in chemical fiber, textile and industrial mining enterprises, as well as malls, hotels and common buildings, while B4-82 type centrifugal fans used for ventilation of flammable volatile gas are the best products as fans used along with purification equipment of air conditioner. And the gas temperature shall not exceed 80℃.
B4-82 type fan is identical with 4-82 type in terms of performance and optional part and can be selected as per samples of the latter.

Ⅱ Form of fan
Fans are of single-suction type with total thirteen machine Nos respectively from 5.6 to 22.4.
Each kind of fans can be made in the form of either right rotation or left rotation. When it is viewed from the front of the motor, the fan is called a right-rotation one and represented by Right in case that its impeller rotates clockwise; those whose impellers rotate counter-clockwise are called left-rotation fans and represented by Left. The location of fan outlet is represented by the angle of air outlet of casing. The Right and Left fans can be made in three angles of 0°, 90° or 180°.

Ⅲ Fan structure
The fan is mainly consisted of impellers, casing, air inlet and drive part.
1. The impeller - welded between arc wheel cover and flat plate wheel disc through backward blade. It is made of steel plate or aluminum alloy and it is in stable operation upon calibration by static and dynamic balance.
2. Casing - volute casing welded with common steel plates. №5.6~11.2 casings are made into integral structure, and №12.5~22.4 housings are made into split type.
3. Air inlet - integral structure of convergent streamline and fixed at the inlet of casing
4. Drive part - consisted of main shaft, bearing stand, rolling bearing and belt pulley.

Ⅳ Performance and selection
The performance of fan generally refers to the capacity of air transmission under standard situation. The specified status of fan is pa0=101325Pa, gas temperature t0=20℃, gas density ρ0=1.2kg/m3
When the actual situation does not match the above specified one, the performance under actual situation must be converted to the one under specified situation, after that, the fan can be selected according to converted performance.

When the fan is put into normal operation upon installation, or the flow is excessively large or small during utilization, one of following methods can be used for removal.
1. To adjust the flow using the extent of opening and closing of the damper.
2. To adjust the flow through changing rotation speed of the fan.
3. To adjust the flow through replacement of fan with higher or lower pressure.
4. To adjust flow through changing resistance factor of pipeline network.

It must be noted that a throttling device is generally used to adjust the flow. But when actual flow is much greater than required one, this method is not quite economical due to too much power waste. If it is permitted, it is usually used to lower rotation speed of the fan or replace the fan with lower pressure.

When the damper is fully open, the flow still seems to be excessively small, then the throttling device does not work any longer. So the user shall try to reduce resistance factor of pipeline network to increase the flow, or the user may increase rotation speed of the fan and replace it with a fan of higher pressure. But rotation speed of the fan generally cannot be changed if the fan is connected to the motor directly and connected through coupling, and only the rotation speed of the fan driven by belt may be varied through changing diameter of belt pulley. However, the highest rotation speed of the fan shall not exceed the highest one in Performance Table and motor power is calculated.

Ⅴ Notes to order
When placing order, please clearly indicate fan model, machine No., rotation speed, air flow, air pressure, angle of air outlet and rotation direction, motor model, power, configuration of fan accessories, etc. Any special requirement shall be promptly proposed at the time of ordering.

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