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How is the air volume of the fan calculated?

How is the air volume of the fan calculated?

The definition of fan air volume is: The product of wind speed V and sectional area F of air duct. Because the wind speed of large fan can be accurately measured by anemometer, the air volume calculation is also very simple. The air volume can be calculated directly by using the formula Q=VF. To determine the number of fans, it is necessary to calculate the total air volume required by the plant according to the air exchange rate of the selected room, and then calculate the number of fans. Calculation formula: N=V × N/Q, in which: N -- number of fans (set); V - site volume (m3); N -- Ventilation rate (times/hour); Q -- single air volume of the selected fan model (m3/h).

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How to select and purchase fans for the plant

How to select and purchase fans for the plant

The fan model shall be selected according to the actual situation of the plant, and the fan model matching the original window size shall be selected as far as possible. The fan and the wet curtain shall be kept at a certain distance (installed on both sides of the gable of the plant as far as possible) to achieve good ventilation effect. The exhaust side shall not be close to the nearby buildings as much as possible to avoid affecting the nearby residents. Fan air pressure: refers to the resistance to be overcome in the process of conveying so many air volumes, and refers to the pressure rise. However, domestic fans are generally selected according to full pressure, while foreign fans are generally selected according to pressure rise. External residual pressure=total pressure of fan resistance of each processing section of the air cabinet. The resistance of the air supply and return duct is generally 7~8Pa/m, and the resistance of 90 ° elbow is 10Pa/piece. Empirical formula: external residual pressure=total pressure of fan - resistance fan power of each treatment section (W)=air volume (L/S) * air pressure (Kpa)/efficiency (75%)/force rate (75%) Total pressure=static pressure+dynamic pressure. Fan motor power (W)=fan power (W) * 130%=air volume (L/S) * air pressure (Kpa)/efficiency (75%)/power ratio (75%) * 130%

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Five Factors Affecting Fan Selection

Five Factors Affecting Fan Selection

Five factors affecting fan selection: 1. Air volume and pressure 2. Operating conditions 3. Exhaust gas composition 4. Installation position and form 5. Accessories, noise and other requirements.

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What are the differences in fan selection under different occasions

What are the differences in fan selection under different occasions

1. Roof exhaust fan shall be set preferentially if heat or steam exhaust is required. 2. When heating, cooling or fresh air supply is required, warm air or cold air flow should be allowed to flow through the position of the staff as much as possible, so pipe fans or side wall fans are often used. 3. For fire fighting and smoke exhaust, roof fans or hoisted air ducts shall be preferred, so pipe fans are often used. Note: Make full use of natural wind and air flow (fan position and form shall be reasonably set). Fan selection in specific occasions 1. Warehouse ventilation (1) To check whether the goods in storage are flammable and explosive, such as paint warehouse, explosion-proof fans must be selected. (2) Depending on the noise requirements, roof fans or environment-friendly centrifugal fans can be selected. (3) The most conventional fan or exhaust fan can be selected according to the air exchange volume required by the warehouse. picture 2. Kitchen ventilation (1) For kitchens that directly discharge lampblack indoors (that is, the air outlet is on the indoor wall), fans or exhaust fans can be selected according to the size of lampblack. (2) For kitchens with large lampblack, lampblack needs to pass through long pipes, and there is bending treatment in the pipes, it is strongly recommended to use centrifugal fans (4-72 centrifugal fans are the most common, and 11-62 low-noise and environment-friendly centrifugal fans are also very practical). This is because the pressure of centrifugal fans is higher than that of axial flow fans, and lampblack does not pass through the motor, so it is easier to maintain and replace the motor. (3) It is suggested that the kitchen with strong lampblack should use the above two schemes together for better effect.

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