Type of fan and specifics (RPM/CFM) needed for blowing dust

Apr 8, 2018
4
0
10
0
Hi,

I'm doing a project whereby I have 3 perspex boxes that are arranged in a triangle and connected by ducting, with a prototype I've been building it contains two fans at either end of each ducting (so at the entrance and exit of each box) with the intention of blowing pigment paint/ground chalk in a circuit between them.

I'm looking for a bit of advice on which type of fan I should use and whether I should be proioritising CFM or RPM with the fan.

Many thanks!
 

kanewolf

Titan
Moderator
Computer fans are obviously not intended for immersion in airborne pigments. Maybe you could do something with a squirrel cage blower where the motor wouldn't be in the airflow and therefore contaminated.
 
My suggestion is to use a single fan for air intake only.
That way, the fan will not be contaminated by whatever is circulating around.
Whatever air that comes in will exit somewhere.

As to RPM vs. CFM, they are directly related.
The faster the RPM for a given fan, the more airflow you get.
Then, also is the diameter of the fan.
Larger fans move more air at a given RPM than smaller ones.
Not relevant to your situation is that the lower the rpm the quieter the fan.
 
Apr 8, 2018
4
0
10
0


Thanks for your help, especially the RPM CFM.

I was thinking about this for the fan: https://www.amazon.co.uk/Industrial-Ventilation-Extractor-Commercial-Controller/dp/B06XGRF2YH/ref=pd_sbs_79_6?_encoding=UTF8&psc=1&refRID=T22W3QM5Y9BNBJ7P1ZWP

Are you suggesting adding the supply fan in addition to the design i mentioned above rough sketch here: http://desouza-jones.tumblr.com/post/172726125820

Not sure how I would incorporate this as I need a situation where the "dust" is moved from each box.
 

Karadjgne

Titan
Herald
Not sure it's going to work as intended. The higher the rpm/cfm of the intake fans, the more air it's going to move. At some point, it'll exceed the ability of the air to sustain viable suspension on the 'dust' and anything in that first chamber will literally get blown out quickly into the 2nd chamber, cascading into the 3rd. Somewhat like a full custom loop with a dry reservoir. You'd need a continuous loop, with no input or exit, so the 'dust' will rotate, eventually returning to the 1st chamber, just like a fcl with a full reservoir, the fan acting like a pump. Unfortunately, in a closed loop system, any air is going to get warmer with use, defeating the purpose after a few minutes.

Systems like this can be done with artificial smoke, on exit the smoke is harmless, but with pigments/chalk dust, it's going to go everywhere.
 
Apr 8, 2018
4
0
10
0
Thanks for your help. So the main obstacles I would need to overcome would be to have supply and exit points somewhere and also use the fans in a way whereby they would't need to push the pigments through the fans themselves for risk of them clogging and breaking.

Perhaps I could try a system based on a vacuum cleaner to push the pigments around the boxes?
 
How about:
A single box with one fan blowing in.
Have a small exit hole with a filter to catch any pigment trying to exit.
Place the part to be coated in the box along with a charge of pigment.
When the fan is turned on, there should be sufficient random air movement to allow the pigment to collect on the part.
You may have to adjust the size of the exit hole.
Too small will not let the interior air flow freely.
Too large, and more of the pigment will collect on the filter.
 

Karadjgne

Titan
Herald
Or use a vacuum cleaner on the far end of the loop, with a filtered box at the center. This would allow air into the reservoir pulling air/dust up a tube, into the 1st box, through the loop, then depositing the dust back into the reservoir. Air/dust won't escape through the filter, the vacuum is too strong to allow that. You could probably hijack a cheap black-n-decker dust buster to do the job.
 
Apr 8, 2018
4
0
10
0


Thank you so much, this is beginning to make sense now. So if I were to add an additional 4th box at the end of the loop with a fan that has a filtered box to supply air into the system but stop it coming out, is that what you're suggesting? One thing I didn't mention is that midway through the system, the second box along I'm hoping to have a tiny exit hole for a small amount of the pigments to exit, I'm guessing this would assist with having an exit supply of air to a small degree.

Also, are you able to recommend any fans that could be used for this? I'm currently building a prototype with computer fans but as was suggested earlier this aren't made to allow for particles to pass directly through them and will likely eventually fail.

I've attached a sketch below, any comments or thoughts would be greatly appreciated:

http://desouza-jones.tumblr.com/post/172789140185

Thanks.
 

ASK THE COMMUNITY

TRENDING THREADS