When you walk into the farm, you will usually see rows of fans hanging on the outer wall of the pig house, neat and spectacular. If you look closely, you will find that fans of different sizes are equipped with either a white or black bell fan. So why install a bell mouth for the fan? How does the installation of the bell mouth affect the performance of the fan? Let's take a look!

Looking at the fan performance chart, you will find that adding a bell to the fan can improve the performance of the fan. Although everyone knows that this is a thing, most people don't know why.

Benefits of using a bell fan:

The reason is that the fan bell can block airflow interference.

The relatively rapid outflow of air from the fan pushes the airflow outside the fan casing, causing the airflow to rotate. The rotating airflow can cause interference at the tip of the blade, reducing the diameter range of the airflow delivered by the fan blade, resulting in reduced airflow. Add a bell mouth to the fan to let the air flow directly along the wall of the bell mouth to prevent the air flow from being blocked by the outside air to ensure its smooth output.

In addition, the bell-shaped design of the bell mouth instead of the straight wall design increases airflow. Air diffusion can reduce the back pressure on the fan blades and improve air flow.

A large number of documents have now shown that the 7° slope of the bell mouth performance is better. The larger the opening angle of the bell mouth, the airflow is separated from the bell mouth wall to form a turbulent flow. The standard length of the bell mouth is 1 to 1.5 times the diameter of the blade. Increasing the flare can improve performance in some areas, but it also makes the fan more susceptible to rain, snow or wind.

The advantages of using a bell fan are unquestionable in pig houses that use a positive pressure system. Whether the pig house is using a positive pressure system or a vacuum system, adding a bell to the fan can also improve the performance of the fan.

It is not recommended to use a bell fan in winter:

When ventilating in winter, a smaller fan type is usually used. It is not a good choice to add a bell to the fan at this time. Conversely, adding a windshield to protect the fan from the effects of strong winds.

The disadvantage of using a bell mouth is that maintenance work due to weather damage increases. It is common for parts on the flare to fall after heavy snow or windy weather. Once the part is dropped, the benefits of using the bell mouth are reduced.

Precautions for installing a fan with a bell mouth:

When installing a fan with a bell mouth, consider increasing the fan spacing as appropriate. The bell-shaped bell mouth design is not suitable for installing the fan too close. In addition, when installing a row of tunnel fans, pay attention to adding extra support to the gable. Ice and snow will accumulate on the bells, adding extra pressure to the gables. For details, consult your pig house construction contractor.