Peripheral knowledge of PPH equipment: selection of fans

How to choose the most suitable fan from the known parameters is what every salesperson must know. Usually, the customer will specify the air volume Qm3/h (CMH) and pressure P (Pa) of a fan. From the performance curve table on the company's catalog, we can choose an optimal model. This parameter The intersection point is as far as possible in the high-efficiency region of the performance curve.

From the performance curve table of the selected model, from the corresponding curves, we can know the shaft power N of the fan, which we need to use when selecting the motor; in addition, we can also find the dynamic pressure Pa, Noise dB (A), speed n, wind speed V and other parameters.

As long as you know the two parameters of the fan's air volume and pressure, you can determine the model of a fan and find other parameters. You can also select the required fan model from the fan selection software.

1. In the case of known air volume and pressure, it is also necessary to understand the working environment of the place of use (such as ordinary, high temperature, explosion-proof, anti-corrosion, etc.), air medium, use, and atmospheric pressure (altitude). , in order to judge which fan to choose (the bearing type and material are different).

2. Under normal circumstances, double-suction fans are used for air supply, and single-suction fans are used for exhaust air (in addition, it depends on whether the air inlet is connected to pipes. It can be used for both exhaust and supply air.

3. Know the place of use and then choose to use the forward or backward fan according to the ratio of pressure to air volume.

4. At present, belt-driven fans are mostly used in the market. The advantages are: strong adjustability, and the actual use can be achieved by adjusting the speed when the system design is deviated. The disadvantages are: the price is higher than the direct-connected type. And the space is relatively large. The direct-connected fan has the advantages of simple use and small space, but the disadvantage is that the working range is small and cannot be adjusted.

5. On the performance curve table of the product catalog, make the intersection of air volume and pressure as far as possible in the high-efficiency area (that is, the outlet air speed is generally between 10-12m/s), and confirm an optimal model. From the performance table of this model, we can find the shaft power, dynamic pressure, noise, speed, wind speed and other parameters of the fan.

6. Sometimes for economical consideration, we also choose a fan with a smaller efficiency than the optimal one, because the fan can be used only by increasing the motor power, and it has an advantage in size and price. However, it is recommended that the wind speed should not exceed 15M/S, otherwise the fan is prone to unstable working conditions, such as vibration and loud noise.

7. Basic reference selection of centrifugal fans: Q (CMH)*10 (single suction is *20) square root, and then push up two models (this is the size of the impeller in mm, and the impeller in other units is converted according to it).

For example: Q=10000CMH is 10000*10(20)=100000(200000) the root number is 316 (447), the model is 400 (560), the Japanese number system (1#=150mm) is 2 1/2# (4#), inch system (1in=25.4mm) is 16-16 (22-22), domestic standard system (1#=100mm) is 4# (5.6#)
In addition, the fan motor power can be converted by the fan efficiency formula.