Why only 6 blades instead of more? More blades = more air, right?

Frequently asked questions about HVLS fans(large industrial/commercial/PMSM fans) and air coolers with explanatory links.

More Blades ≠ More Air

First, More fan blade does not mean more air. It is a balance of total efficiency with consideration of noise level and air volume. You will not get much air if you cover most of the area or the whole area with blades. Such a fan will be useless. We have not just selected 6 blades for our fans, we have tried and tested everything on an experimental basis and then we came with the idea of 6 blades. It is the best possible option for high volume low speed (HVLS) fans.

Our first HVLS big industrial ceiling fans were made with 10 blades and then 8 blades as the second generation. Having 6 blades is the amendment as the 7th generation of our large industrial ceiling fans. We have tried to make our products cost-effective, efficient, better and durable. We are still trying to improve our fan design for better efficiency.

Creating a larger airfoil wasn’t simply the answer to improving efficiency. The airfoil must work efficiently through a range of speeds. When an HVLS fan rotates, the end of the blade moves faster than it does at its fixed point at the chassis, the fan blade angle also gives impact to airflow. While airflow patterns needed strong research and consideration. We did research and we are still trying to come up with innovative and effective ideas to make our fans the best industrial ceiling fans.

When engineers experimented with the airfoil shape, they discovered that a larger shape allowed them to reduce the number of blades. Final fan design decreased from 10 to 8 and then 6 blades, without a corresponding drop in fan performance.

Reducing the number of blades was proved to be beneficial. Moreover, it had also reduced the torque which increased the life span of the fan. A fan’s lifespan is related to torque:

Horsepower = Torque * Revolutions Per Minute (RPM) 5252

As RPM goes up, torque goes down for the same horsepower. Our engineers also found that, due to the longer airfoil shape, 6-blade HVLS fans rotate faster than 8 or 10 blade fans, which lowered the torque. Since torque is constant stress on a fan’s motor, bearings, and gear; therefore, less torque meant longer fan life.

Why do your HVLS fans have only 3 fan blades?

There are high volume low speed (HVLS) fans available in the market with 3 blades. Due to the fewer number of blades, the cost of the fan is also less. The problem with such a design is low airflow. Such fans cannot provide a high volume of air at low speed as compared to fans with more blades. The number of blades plays an important role. It should be perfect to cover more area to provide excellent airflow at low speed.

RTFANS has done a lot of research on the number of blades. We have tested many ideas and finally, we came up with the idea of 6 blades. We found the best performance of HVLS fans in the case of 6 blades. This was our 7th amendment and we are still proud of it. 6 blades provide high volume airflow at low speed.

Hence, 6 blades are for the best performance of our high volume low speed (HVLS) fans.


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