It might sound a bit strange since cubic feet as a unit of volume and not mass or weight. The unit of measurement for the flow rate is CFM which stands for Cubic Feet per Minute. The mass flow rate mathematical definition is: dm/dt which is the derivative of the mass with respect to time. The term "mass flow rate" refers to the amount of material that passes through the fan per unit time. So let's take a closer look at these concepts before we start using the calculator. In particular, in the fan world, we use the term "mass flow rate" and a unit called cubic feet per minute (CFM). However, when we are talking about airflow being a more complex quantity than pressure, there are certain remarks and special units that should be used.
The way pressure is mentioned and used in the fan world is reasonably standard and does not call for the use of exotic units of measurement. Hence, higher pressure is required to avoid the flow of air being completely obstructed.
On the other hand, pressure-optimized fans are designed for situations in which there is an object blocking the airflow like a radiator. The idea is that an airflow optimized fan will be better for moving significant amounts of air in an unrestricted scenario, i.e., when there's nothing close to the fan that may obstruct the flow. This distinction between airflow or pressure optimization of a fan is important in some aspects but is also very hard to parametrize, which is why it's left out of this fan CFM calculator. Efficiency - Is the ratio between power input and power output expressed as a number between 0 and 1.Power - It measures the power produced/consumed by a fan (respectively called power output/input).Blade shape - Depending on the design of the fan blade, a fan can be optimized for air pressure, or airflow.Size - Parametrized by the diameter of the circumference the fan covers.Now that we have talked about the types of fans and their places, it's time to talk about the things that make one fan different from another.
Hereafter we shall not discuss those types of fans. The last type of fans you can find are sports fans, but those are not very efficient at moving air and make a lot of noise. Here we can include computer fans easily, both the fans used to cool it and the USB or battery-powered fans that cool you. They are also available in a wide variety of designs, sizes, and prices. They strike a balance between mass flow rate (don't fret, we will explain later what it is) and noise. The best known are outdoor and standing fans like the ones you would pull out on a hot summer day in the hope of a refreshing breeze. We also have bathroom fans which could fall into the ventilation category since bathroom fans are barely ever meant to be seen. Finally, they should, at the very least, not detract from the appearance of the room they are located in. On the other hand, ceiling fans tend to be quiet since, apart from the obvious function of moving air, they should not disturb people having conversations under them. Because they are generally hidden they barely ever serve any aesthetic purpose. For ventilation purposes, fans tend to be ugly and big but powerful and optimized for performance rather than silence. Regarding what types of fans we expect to find in each place, we should start with the obvious: most fans exist in hot places and closed spaces.
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