Output of Air Movers

Fans are used on water restoration jobs. In the water restoration industry they are often called “air movers”

They range from high output to relatively little. Which one you will use depends on the Airflow needed, in each situation.


Two Measurements of Airflow


CFM - This is cubic feet of air per minute, coming out the front of the unit. It varies, on different units, from hundreds to thousands of cubic feet per minute.

Lift - This is the strength of the air. Does the unit have the power to keep moving when it needs to push through attachments or lift floated carpet? The original concept of “lift” comes from a mercury meter, in a laboratory, that moves up a scale. (Sort of like a thermometer) The higher the meter reads, the more lift or strength exists.


NOTE: more lift uses more amps of electricity



Two Basic Designs of Air Movers




These have a drum inside that spins horizontally pushing air out the snout. This airflow is created by blades that have been bent up, on the drum. Circular force, like that created by the drum, is called “centrifugal.”

These fans usually have high lift; they are strong. They have to be strong to do the work that they are asked to do.

Typically, they are lower volume (CFM) and higher lift (AMPS) machines designed for work loads. They used to average about 9 amps of electricity use, while newer machines have more efficient motors and can be down around 4 amps.


Interesting – A centrifugal fan under a load actually runs “easier” because of the backflow of air, than a unit running flat out with no load.




These fans have elephant ear type blades attached to an axle. Fire departments often have large ones to remove smoke from burning buildings. The design of the blades makes huge amounts of air, often around 3,000 cubic ft/min. These units can be two types, when it comes to lift; (power) low pressure or high pressure. Low pressure units have weak motors. It gets away with it because it only moves air. It will not have attachments or be asked to float a carpet.

Because of this low “lift” or “pressure”, these air movers can move large volumes of air with as low as a 1.5 horsepower motor. This means less units will put out more air. Also, if needed, more units can be run on a single circuit.

There are also high pressures axials. That are asked to push Injectidry equipment or move air through duct work. These draw more amps; possibly as high as 9. They, usually, will not slow down under a load.


Another difference, between the two, is Centrifugals are “laminar” or a layer close to the floor, while axials blow out air, but not laminar. Some are designed to direct the air down.

These air movers have a job to do. Know each one and when and how to use them.

Dennis Klager



Copyright 2012 by Dennis Klager