The fan is a kind of machinery used to compress and transport gas. From the point of view of energy conversion, it is a kind of machinery that converts the mechanical energy of the prime mover into gas energy.
According to the principle of action classification, fans can be divided into:
· Turbofan – a fan that compresses air by rotating blades.
· Positive displacement fan – a machine that compresses and transports gas by changing the volume of the gas.
Classified by airflow direction:
· Centrifugal fan – After the air enters the impeller of the fan axially, it is compressed under the action of centrifugal force and mainly flows in a radial direction.
· Axial-flow fan – The air flows axially into the passage of the rotating blade. Due to the interaction between the blade and the gas, the gas is compressed and flows approximately in the axial direction on the cylindrical surface.
· mixed-flow fan – The gas enters the rotating blade at an Angle to the main shaft and flows approximately along the cone.
· Cross-flow fan – the gas passes through the rotating blade and is acted by the blade to increase the pressure.
Classification by high or low production pressure (calculated by absolute pressure) :
Ventilator – exhaust pressure below 112700Pa;
· blower – exhaust pressure ranges from 112700Pa to 343000Pa;
· compressor – exhaust pressure above 343000Pa;
The corresponding classification of fan high and low pressure is as follows (in standard state) :
· Low pressure centrifugal fan: full pressure P≤1000Pa
· Medium pressure centrifugal fan: full pressure P=1000~5000Pa
· High pressure centrifugal fan: full pressure P=5000~30000Pa
· Low pressure axial flow fan: full pressure P≤500Pa
· High pressure axial flow fan: full pressure P=500~5000Pa
Way of centrifugal Fan naming：
For example: 4-79NO5
Way of model and style:
For example: YF4-73NO9C
The pressure of the centrifugal fan refers to the boost pressure (relative to the pressure of the atmosphere), that is, the increase of the pressure of the gas in the fan or the difference between the gas pressure at the inlet and outlet of the fan. It has static pressure, dynamic pressure and total pressure. The performance parameter refers to the total pressure (equal to the difference between the total pressure of the fan outlet and the total pressure of the fan inlet), and its unit is commonly used Pa, KPa, mH2O, mmH2O, etc.
Flow:
The volume of gas flowing through the fan per unit time, also known as the air volume. Commonly used Q to represent, the common unit is; m3/s, m3/min, m3/h (seconds, minutes, hours). (Sometimes also used “mass flow” that is, the mass of gas flowing through the fan per unit time, this time need to consider the gas density of the fan inlet, and the gas composition, local atmospheric pressure, gas temperature, inlet pressure has a close impact, need to be converted to get the customary “gas flow”.
Rotational speed:
Fan rotor rotation speed. It is often expressed in n, and its unit is r/min(r indicates the speed, min indicates the minute).
Power:
The power required to drive the fan. It is often expressed as N, and its unit is Kw.
Common fan usage code
Transmission mode and mechanical efficiency：
Fan common parameters, technical requirements
General ventilation fan: full pressure P=… .Pa, traffic Q=… m3/h, altitude (local atmospheric pressure), transmission mode, conveying medium (air can not be written), impeller rotation, inlet and outlet Angle (from the motor end), working temperature T=… ° C (room temperature can not be written), motor model…… .. wait.
High temperature fans and other special fans: full pressure P=… Pa, flow Q=… m3/h, imported gas density Kg/m3, transmission mode, conveying medium (air may not be written), impeller rotation, inlet and outlet Angle (from the motor end), working temperature T=….. ℃, instantaneous maximum temperature T=… ° C, imported gas density □Kg/m3, local atmospheric pressure (or local sea level), dust concentration, fan regulating door, motor model, import and export expansion joint, overall base, hydraulic coupling (or frequency converter, liquid resistance starter), thin oil station, slow turning device, actuator, starting cabinet, control cabinet… .. wait.
Fan high speed precautions (B, D, C drive)
·4-79 type: 2900r/min ≤NO.5.5; 1450 r/min ≤NO.10; 960 r/min ≤NO.17;
·4-73, 4-68 type: 2900r/min ≤NO.6.5; 1450 r/min ≤15; 960 r/min ≤NO.20;
Fan often used calculation formula (simplified, approximate, general use)
Elevation is converted to local atmospheric pressure
(760mmHg)-(sea level ÷12.75)= local atmospheric pressure (mmHg)
Note: Altitudes below 300m May not be corrected.
·1mmH2O=9.8073Pa;
·1mmHg=13.5951 mmH2O;
·760 mmHg=10332.3117 mmH2O
· Fan flow 0 ~ 1000m at sea height can not be corrected;
· 2% flow rate at 1000 ~ 1500M elevation;
· 3% flow rate at 1500 ~ 2500M elevation;
· 5% discharge at sea level above 2500M.
Ns:
Post time: Aug-17-2024