classification

◆ Fans can be classified into several types based on the material used, such as iron shell fans (ordinary fans), fiberglass fans, plastic fans, aluminum fans, stainless steel fans, and so on

◆ Fans can be classified according to the direction of gas flow, including centrifugal, axial, mixed flow, and cross flow types.

◆ After entering the impeller of the fan axially, the airflow mainly flows radially. This type of fan is made based on the principle of centrifugal action, and the products include centrifugal ventilation fans, centrifugal blowers, and centrifugal compressors.

◆ Axial flow fan. The airflow enters the impeller of the fan axially and flows approximately along the axial direction on a cylindrical surface. This type of fan includes axial flow fans, axial flow blowers, and axial flow compressors.

◆ Rotary fan. Using rotor rotation to change the volume of the air chamber for operation. Common varieties include Roots blowers and rotary compressors.

◆ Fans are divided into axial flow fans, centrifugal fans, and mixed flow fans based on the direction of airflow entering the impeller.

◆ Fans are divided into compression type local fans (hereinafter referred to as compression type fans) and explosion-proof motors placed outside or inside the flow channel, and explosion-proof motors placed in explosion-proof sealed chambers for extraction type local fans (hereinafter referred to as extraction type fans).

◆ Fans can also be divided into single, double, or multiple pressurized fans according to the form of pressurization. If 4-72 is a single pressure fan, the fan is a multi pressure fan.

◆ Fans can be divided into axial flow fans, mixed flow fans, roof fans, air conditioning fans, etc. according to their purposes.

◆ Fans can be divided into low-pressure fans, medium pressure fans, and high-pressure fans according to pressure.

◆ Divided by outlet pressure (boost): ventilation fan (≤ 15000 Pa), blower (150000-350000 Pa), compressor (≥ 350000 Pa).

Fan performance parameters

The performance parameters of a fan mainly include flow rate, pressure, power, efficiency, and speed. In addition, the magnitude of noise and vibration are also major design indicators for fans. Flow rate, also known as air volume, is expressed as the volume of gas flowing through a fan per unit time; Pressure, also known as wind pressure, refers to the increase in pressure of gas inside a fan, which can be divided into static pressure, dynamic pressure, and total pressure; Power refers to the input power of the fan, that is, the shaft power. The ratio of fan power to shaft power is called efficiency. The total pressure efficiency of the fan can reach 90%.

Application scope

Fans are used for ventilation, dust removal, and cooling in factories, mines, tunnels, cooling towers, vehicles, ships, and buildings; Ventilation and induced draft for boilers and industrial furnaces; Cooling and ventilation in air conditioning equipment and household appliances; Drying and selection of grains; Wind tunnel wind source and inflation and propulsion of hovercraft. The working principle of a fan is basically the same as that of a turbo compressor, except that due to the low gas flow rate and small pressure changes, it is generally not necessary to consider changes in gas specific volume, that is, to treat the gas as an incompressible fluid.

precautions

◆ Grounding of fan casing or motor casing;

◆ Prohibit reverse rotation, prohibit rated current operation, and prohibit phase loss operation;

◆ It is prohibited to maintain the fan during operation.

debugging

◆ Fans are allowed to start or start at full pressure, but it should be noted that the current during full pressure starting is about 5-7 of the rated current, and the starting torque is proportional to the square of the current. When the grid capacity is insufficient, starting should be used. When the power is greater than 11KW, it is advisable to use starting. ）When testing the fan, carefully read the product manual and check whether the wiring method is consistent with the wiring diagram; It is necessary to carefully check whether the working voltage of the power supply for the fan meets the requirements, whether the power supply is out of phase or in phase, and whether the capacity of the electrical components provided meets the requirements.

◆ During the test drive, there should be no less than two people, one to control the power supply and one to observe the operation of the fan. If any abnormal phenomena are found, the machine should be stopped for inspection; First check if the rotation direction is correct; After the fan starts running, it should be checked whether the operating current is balanced and whether the current exceeds the rated current; If there is no normal phenomenon, the machine should be stopped for inspection. After running for five minutes, stop the machine and check if there are any abnormalities in the fan. Confirm that there are no abnormalities before starting the machine.

◆ When testing a dual speed fan, start at low speed first and check if the rotation direction is correct; When starting at high speed, wait for the fan to come to a stop before restarting, and then rotate in the opposite direction at high speed, causing the switch to trip and the motor to be damaged.

◆ When the fan reaches normal speed, it should be checked whether the input current of the fan is normal, and the operating current of the fan should not exceed its rated current. If the operating current exceeds its rated current, check whether the voltage supplied to the fan is normal.

◆ The required motor power for the fan refers to the higher power required for the centrifugal fan and fan case when the air inlet is fully open under operating conditions. If the air inlet is fully open for operation, there is a possibility of damage to the motor. During the fan test run, close the valve on the outlet pipeline of the fan, gradually open the valve after operation until the desired working condition is reached, and pay attention to whether the operating current of the fan exceeds the rated current.