# Need recommendations for 4"-6" blower for fume hood.



## CR2008 (Oct 24, 2010)

Hello all, I got my small fume hood in some days ago, and the makers recommended a blower that is at lest 200cfm, and I wanted to know if anyone could recommend a good blower that can deal with corrosive fumes (gona make a filter for absorbing some of the acid fumes using impregnated activated carbon, but it won't absorb 100%).

I did a quick search on ebay and found some 4" blowers made out of plastic and listed as "corossion resistant" under the boat parts section, for blowers to remove engine exhausts. Other than something like this, there are dedicated lab blowes but these are VERY expensive, about $2000 or so as listed in the cole palmer catalogs.

Are there any good alternatives to the typical fiberglass lab blowers out there, that can pull at lest 200cfm and also made out of plastics that won't rust?

Gona use the fumehood for boiling down Sulfuric acid, distilation of nitric acid etc.


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## Harold_V (Oct 25, 2010)

Don't use a squirrel cage blower. They pack off quickly, although if you don't use your fume hood for incineration (I did), that may not be nearly as big a problem as it was for me. 

W.W. Grainger sells a paddle wheel type blower that will serve your needs. I used to use one for my fume hood. After it was purchased, it was dismantled, sand blasted, then covered with an acid resisting epoxy paint. Under constant use (I refined commercially), it served for several years. 

Harold


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## 4metals (Oct 25, 2010)

Don't forget to figure in the CFM resistance a carbon filter before the blower will add to your system and increase the blower CFM accordingly.


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## CR2008 (Oct 25, 2010)

4metals said:


> Don't forget to figure in the CFM resistance a carbon filter before the blower will add to your system and increase the blower CFM accordingly.



How do I calculate this? Over the weekend I will do some searching on this because I was going to get a blower with maybe 300cfm to compensate for the filter.

I would rather a tried and true formula though, makes me feel better.


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## Barren Realms 007 (Oct 25, 2010)

CR2008 said:


> 4metals said:
> 
> 
> > Don't forget to figure in the CFM resistance a carbon filter before the blower will add to your system and increase the blower CFM accordingly.
> ...



Generaly figure 1,000 cfm per sq ft of face area. A flat filter close woven will reduce your flow by aprox 20%. Carbon filter will possibly reduce by another 50-75% depending on flow capability, haven't seen any figures on this.


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## CR2008 (Oct 25, 2010)

Barren Realms 007 said:


> CR2008 said:
> 
> 
> > 4metals said:
> ...



So is it safe to guess that I would need something in the 500cfm range or so? How about if I used 2 250cfm blowers in with a Y connection? Would something like that compensate?

Thanks


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## Barren Realms 007 (Oct 25, 2010)

It is possible to set something like that up.


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## CR2008 (Oct 25, 2010)

Harold_V said:


> Don't use a squirrel cage blower. They pack off quickly, although if you don't use your fume hood for incineration (I did), that may not be nearly as big a problem as it was for me.
> 
> W.W. Grainger sells a paddle wheel type blower that will serve your needs. I used to use one for my fume hood. After it was purchased, it was dismantled, sand blasted, then covered with an acid resisting epoxy paint. Under constant use (I refined commercially), it served for several years.
> 
> Harold



What exact brand/model was used? I went to the grainger web site and they had many different brands and types.


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## Harold_V (Oct 26, 2010)

CR2008 said:


> What exact brand/model was used? I went to the grainger web site and they had many different brands and types.


Explore the Radial Blade blowers----
The model I used was the 2C863. The opening of my fume hood was approximately 5 square feet, with the blower sucking through a 24" x 25" (furnace) filter. When the filter was new, the blower moved more air than was necessary. I may have enjoyed success with the next smallest blower, 2C862, but I also incinerated with my hood, so I relied on moving large air volumes to cool the stack (which was Transite pipe). Were I to face the same circumstances today, I'd duplicate the original setup, which worked perfectly well. Of course, today, you can't buy Transite pipe any longer. 



Harold


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## Texas (Oct 27, 2010)

Hi, I intend to do my fume hood, putting a simple fan blowing inside the fume hood, and will be closed with a glass window, and will have her chimney, what do you think about that?, I will do because I dont have much money...still
One question, what type of filter used for nitric acid fumes and others?


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## Harold_V (Oct 28, 2010)

Texas said:


> Hi, I intend to do my fume hood, putting a simple fan blowing inside the fume hood, and will be closed with a glass window, and will have her chimney, what do you think about that?, I will do because I dont have much money...still
> One question, what type of filter used for nitric acid fumes and others?


The hood shown above was equipped with a (readily removable) glass cover. Notice that there's fresh air feeding both sides (the 6" diameter light green tubes). 
Didn't work worth a damn. Unless you can throttle your blower so it moves only a miniscule amount of air, there's so much turbulence in the hood that it gives your flame(s) fits, and dissipates heat all too rapidly.

Don't put anything inside your fume hood you don't want destroyed. A motor inside wouldn't last long, assuming you work with HCl and sulfuric acids. 

I used simple fiber glass furnace filters. Didn't care if they had stamped steel inserts restraining the fiber glass as some do. I incinerated the filters, sending the stamped steel to my stock pot, where any values contained were eventually recovered, and the steel was very welcome. 

An incinerated furnace filter will reduce to just a small hand full of dirt. Even the glass, once incinerated, loses its strength and reduces readily. Do not discard the filters. In spite of your most careful work, they will bear values. 

Harold


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## Texas (Oct 28, 2010)

True, had not taken into account the air blowing on the flame, and observing carefully your fume hood, is "hamster wheel", so that fumes do not touch the motor.
Thanks Harold V


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## qst42know (Oct 28, 2010)

From what Harold has described before, the paddle wheel type impeller shown here.

http://www.blowerwheel.com/blower-wheel-radial.htm


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## Texas (Oct 29, 2010)

qst42know, thanks for the link, the plastic fan wheel is the solution.
Texas.


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## capt_dugout (Jul 17, 2011)

has anybody tried using pressurized air to pull the fumes out by vaccume ? a jet put in a 90% elbow and size stepped up should creat a good vaccume. this would also be adjustable according to air pressure at the orifice and would not require much volume.


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