Fan FAQs

All-Terrain VENTRY Fans - Home

Dealer Locator

Fans / Blowers

 

FAN FAQ TOPICS:

Carbon Monoxide / CO Levels
Electric fans
Exhaust extensions

Honda GC versus GX motors
Negative pressure ventilation (versus PPV)
Fan lifespan and durability
Fan stability and walking
Best seller
Safety Light option
Noise levels

Propeller composition and blades
Wood versus metal propellers
Pneumatic versus solid rubber wheels
Fan placement
Fan horsepower versus size
Confined space ventilation
Shrouds
Troubleshooting
Thrust You are here
Warning

How is thrust a measure of fan performance (in addition to CFM)?

Thrust is actually a better measure of air volume than CFM because there are fewer variables in the measurement process. Thanks to that handy law of physics (Newton’s 3rd Law of Motion) that for every action there is an equal and opposite reaction, it follows that the more air a fan pushes, the harder the fan will also be pushed backwards. Fans must be engineered in such a way as to handle that thrust without walking, rotating, or falling over!

Below is a flyer describing our thrustometer or thrust-measurement apparatus. A simplified version can be done by setting a fan on top of a piece of plywood and the plywood on top of a couple of pipes or broomsticks (rollers). Attach the fish scale to the front of the guard and to something solid in front of the fan so as the fan pushes backwards, it pulls on the scale.

Positive Pressure Ventilation Fans Thrust Measuring Device  

Note: To approximate the volume of air being pushed, multiply pounds of thrust by a little over a thousand cubic feet/pound.

As a rule of thumb, you should have 11-15 pounds of thrust for residential fires, 15-18 pounds for commercial fires, and 18+ for industrial fires.

Click to download thrust measurement flyer
Click image above to download
a flyer on measuring thrust (PDF)

Fun Application of Thrust

Dad and James needed to move a couple docks across Hauser Lake this spring, about a mile. They first used a small boat supplemented by our shop fan, a propane powered 24GX200 VENTRY. At the end of the journey, they had to maneuver the docks down a long, narrow canal to the beach, so they just let the fan do it all. It worked remarkably well!

In these photos (click them for larger view) you can see the wake of the docks moving through the water. Using the LP VENTRY Fan was equivalent to standing in the water and pushing against the docks with 20 pounds of force. Thrust is a great thing, as long as your fan is designed to handle it, as VENTRY Fans are.

By the way, would we do this with a fan that might walk?! Of course not! VENTRY Fans stay put.

Using thrust to push docks

Using thrust to move docks

 


Good, bad, or otherwise, we appreciate your feedback on this website! J. Neils Enterprises, Inc. - Home of All-Terrain Air, Power and Light. 888-257-8967. J. Neils Enterprises is located on Hauser Lake in Hauser, Idaho Copyright 2007 J. Neils Enterprises, Inc. All Rights Reserved