Filtering hydrocarbon vapors

[cliffy]

Hi all. I don't know if this is the right forum for this so sorry if it's not.
I am wondering if it is possible to filter gasoline or diesel or fuel oil, etc. vapors out of a stream of air coming from a shop vac.
As you may have guessed, the shopvac is not expolsion-proof/inherently safe but I would like to make it so on the cheap.
The flow will be around 50-100 cfm @ 30 psi max.
I'm assuming the media will involve activated charcoal or similar, but a couple hours of searching has not turned up anything promising.
Any thoughts?
thanks

 

[moltenmetal]

You're risking disaster by doing this, especially with the gasoline! You'd need the carbon filter to be on the INLET, because the motors on these units are open sources of ignition- they're all brushed "universal" motors which run immediately adjacent to the material being vacuumed. If there's an explosive mixture drawn into one of these, they WILL blow up! Filtering the outlet would not save you. Needless to say, that wouldn't be very practical in ShopVac configuration, since all the crap you're trying to suck up would end up plugging the carbon bed.

Do yourself and your family a favour and just keep the ShopVac away from the gasoline, or even the sawdust or kitty litter you used to soak up the gasoline etc. The diesel's much less of a risk due to its flash point, but still not a good idea.

 

[cliffy]

Thanks for the reply, moltenmetal. I guess I was thinking that the motor was separate from the intake stream.
Perhaps I can replace the standard motor with a hazardous location type. I'll have to think about this more.

My hovercraft is full of eels.

 

[moltenmetal]

Doubtful you can find a 5000 rpm hazardous location motor to fit a ShopVac!

What are you after? Collection of the liquids themselves, or collection of sawdust/kitty litter absorbents etc?

If it's the former, extreme caution is required. Static discharge is a big concern- not just the motor arc.

If it's the latter, consider a dust collector blower with a 3-phase TEFC motor. Use METALLIC ducting, and make sure it is completely and continuously grounded. Make sure the dust collector blower has a non-sparking impeller- aluminum is fine, and obviously steel is not! Mount the motor switches in the general purpose (non-hazardous) area or use hazardous duty equipment- Div 2 is fine if you direct the discharge to the outdoors etc.

 

[cliffy]

Hi molten. Actually, the medium being vacuumed is soil and pea gravel that MAY have some fuels in it, not by any means puddles of gas or soaked absorbent or anything like that.
Still, any vapors exposed to an ignition source is a no-no of course.
Shop vacs run at 5K rpm? I didn't know that.
Might be time for Plan B.
Thanks for the advice.

My hovercraft is full of eels.

 

[unclesyd]

Do a Google Search on Vacuum Excavators. The use external blowers/vacuum pumps to help eliminate the possibility of any sparking problems. They also use large equipment to allow ingress of extra air to mitigate any problems.

 

[cliffy]

unclesyd: That's a good idea, thanks.

My hovercraft is full of eels.

 

[lastone]

I know of someone that thought they could use their shop-vac to pick up a gasoline/dirt mixture.

He no longer has a garage.