Blower CFM vs work area

[Gene Uselman]

Post by Mike Henry » Fri May 12, 2017 6:32 pm

Is there a general guideline for how much exhaust air flow that is needed for a given work area? I'm assuming that a 20x28 laser needs more exhaust flow than a 12x20 laser but I don't recall seeing any recommendations.

Post by Pete Cyr » Fri May 12, 2017 7:02 pm

More is generally better. I recommend 400 - 600 cfm.
350 CFM would be on the extreme low end for your size bed.
What you plan to primarily cut will have an impact on how much exhaust you need.
The more smoke/off gassing to more exhaust you will need.
Air assist will generally keep you laser head lens clear of debris and particulates.
The major issue with smoke/off gassing is baking it on the mirrors reflecting the beam to the laser head.
Discharging exhaust out side vice discharging to an internal filter will reduce the back pressure and provide a better flow rate in most instances.
More CFM is better (sucking the chrome of the screw heads is too much)

Post by Gene U- 3.11.19

I have been working with air flow and exhaust fans lately as I update my laser- here is a CFM chart for 6" ducting"

Duct chart.jpg

Common 'Snail' exhaust fan- 550W= 635 CFM- I have a 750W, not sure of the CFM.

Snail exhaust fan.jpg

As you see, flex tubing disrupts the flow as well as elbows and other restrictions. It is good to clean the fan occasonally- here is mine after 3 years.

Exhaust blower after 3 years.jpg

The size of the cabinet makes a difference of course- length, width and depth for volume, and the design makes a large difference- I use a inline duct blower in my daughters which is 440CFM and much quieter than the 550W that came with the machine. The design is unusual [to me] when I bought it, but seems very efficient. I found an actual picture of the bed design:

Automation tech bed design.jpg

Automation tech bed pict.jpg