Sciencemadness Discussion Board

Are these inline fans generally brushless?

antimon - 24-6-2015 at 00:56

Hi, i am going to build a fume hood, and i wanted to ask if these kinds of inline fans are brushless, so you don't have to worry about anything blowing up if you would work with solvents?

https://images.duckduckgo.com/iu/?u=http%3A%2F%2Fi.ebayimg.c...

I am going to make a fume hood like this one, that will mostly be used for soldering, and stuff like that, but i also want to be able to do electroplating and simple chemical reactions in it. The best thing to do is to make it out of stainless steel sheet metal right away, maybe?

https://images.duckduckgo.com/iu/?u=http%3A%2F%2Fhackadaycom...

Thanks.

[Edited on 24-6-2015 by antimon]

Zombie - 24-6-2015 at 01:21

The fan you pictured appears to be a Bilge fan for marine use.
Yes they are inductive motors, brush-less, and ignition proof. They are generally sold in DC voltages so be sure to buy the correct voltage for your setup.

You can also make most other types of "brushed" motors ignition proof by installing stainless steel screen around any air entry points.

bob800 - 24-6-2015 at 06:51

Keep in mind that Bilge blowers like the one pictured generally do not move enough air to maintain an adequately fast face velocity (how fast particles of air are drawn into the hood). It would certainly draw some of the fumes away, but you should expect a significant amount of fumes to escape into the room, so I wouldn't use that fan for anything involving dangerous gases or lots of solvent fumes.

If you are dealing with a sufficient amount of solvent fumes that you're worried about them "blowing up", then you should NOT use a relatively weak blower like this. Do a search for "fume hood" as the subject on this forum and you can learn how to build a proper fume hood with face velocity calculations. The idea is to remove the solvent fumes at a fast enough rate so there's no buildup of flammable vapor in the first place, rather than just praying that they won't ignite.

If you just want to solder in it, then no problem.

"The best thing to do is to make it out of stainless steel sheet metal right away, maybe? "

If you have the materials and tools to do that, yes, but wood covered with ceramic tiles is simpler to implement and just fine for most uses.

aga - 24-6-2015 at 08:19

The experiments you're doing (and your cash) dictates the level of fabulous-ness and effectiveness of your fume hood.

Mine is fine for all of the basic stuff i do, yet would be totally inadequate for handling extremely corrosive or explosive gasses.

If i were ever to progress to very nasty and dangerous chemistry, then i'd upgrade the entire thing to a shop bought professional setup, probably in a new building designed for the purpose as well.

Horses for courses basically.

alive&kickin - 6-5-2016 at 05:03

Sorry for the old revival, but I thought this might be of interest to those looking to build a fume hood on the cheap and I haven't found it mentioned anywhere. Camera broke, so no pictures, but I use the fan from an old, scrapped dryer. It moves a lot of air, works on the mains, has a plastic input and output from the fan(which is also made of plastic), and has the motor outside the fan and ducts. I'm not sure what all it might stand up to, but it works well for all I have done. Hope this helps someone with a limited budget. They can usually be had at scrap yards(people trash them when the heating element goes out) but the fan is still good.

Dr.Bob - 6-5-2016 at 05:50

The drier fan will move lots of air, but is likely a sparking motor, so you would not want to use it with any real quantity of ethers, ketones, hydrocarbons, and other highly flammable chemicals. But it would work fine for most simple chemistry and acid fumes. (At least until it corrodes).

CharlieA - 6-5-2016 at 15:42

quote] and has the motor outside the fan and ducts.[/rquote]

Is this a "squirrel-cage" type blower? I've wondered about using this for a hood, because the exhaust could be kept separate from the motor.

alive&kickin - 10-5-2016 at 23:13

CharlieA, the one I have is a squirrel cage type, but I have also seen the turbo type. I know it's sealed good because coming out of a dryer any dust from lint has the possibility of starting a fire if it hits a spark from the motor, something manufacturers are sure to protect from.

squirrel-cage blowers

CharlieA - 11-5-2016 at 16:55

Quote: Originally posted by alive&kickin  
CharlieA, the one I have is a squirrel cage type, but I have also seen the turbo type. I know it's sealed good because coming out of a dryer any dust from lint has the possibility of starting a fire if it hits a spark from the motor, something manufacturers are sure to protect from.


Thanks for the info. So I assume that you are using a squirrel-cage blower in a DIY hood. Are you pleased with it? Do you know how many CFM it moves? What is the duct size?

Pardon all the questions, but I have an old dust filter for a woodworking shop that I think has a squirrel cage blower which I intend to re-purpose.

alive&kickin - 11-5-2016 at 19:26

CharlieA, you're right, squirrel cage in a DIY fume hood. Happy as could be with it. It's 5" ducts in and out but I'm not sure how much air it moves. Working great for me so far!

CharlieA - 12-5-2016 at 17:46

Thanks! Now to tear into that dust filter.....