Power for a radiator fan to use as a spray booth extractor

[boatbuilder]

Just picked up a double fan unit from a SEAT. Planning to use it in my diy spray booth to suck out the over spray.
They are obviously 12 volts but any ideas what I could use to power them apart from a car battery?
Not sure how long it would run on a car battery before it went flat?

[Margo88]

You can buy 240vac - 12vdc transformer on rs components. You can then plug the transformer into the mains and connect the fan to the transformer. You will need to know the power rating of the fan though

[boatbuilder]

I think it's 80 amps!

[Paul Weeding]

size is the cable that feeds it??

80amp would be like starter cable

[boatbuilder]

Ah i meant 80 watts! thats on normal speed. 350 watts at high speed.
Looks like two cables feeding it, one for high speed and a slightly thinner one for normal speed. Slightly chunkier wires than say normal wiring but nothing massive.
Trying to do this on the cheap so don't really want to buy anything else if I can help it!

[boatbuilder]

I think 350 watts is 29 amps at 12v.
So am I right in thinking that if you had a fully charged say 70 AH battery, you would get a run time of 70÷29= 2.4 hours?

[Oldiebut goodie]

I always work on not taking a battery below 50% to keep it in good nick. So halve that - 1 hour.
I notice that you haven't said anything about how you are going to make the fan sparkproof (it should be good to start with but I doubt that it is rated for potentially explosive atmospheres). Look at what happened at the wood dust factory and I should think theirs were sparkproof.

[boatbuilder]

Yeah I know but I'm just using Rustoleum so wouldn't be just as explosive as 2k paint thinners I would imagine.

[colinthefox]

It is very dangerous to use that type of fan for a spray booth extract.

Rustoleum thinners can be just as explosive too, as can sawdust, flour, icing sugar, coal dust, etc etc it's all about the mixture of air and fuel you get.

OBG is right about the fan not being sparkproof, but that's not the whole story. It's not just the sparking that can cause an explosion. There are two types of fan that will do the job, one is called bifurcating (that is the motor is out of the vapour laden airflow), and the other is called flameproof, which is a construction where all the hot and sparky bits are inside a cast iron enclosure so even if the vapour ignites in the enclosure, it won't spread to outside. Both are very expensive.

I'm not sure what to recommend in your case. You might well get away with running any old fan if you don't spray for more than a couple of minutes at a time, or might not. Do you play Russian Roulette often? I'm sure most of us have sprayed stuff without the proper gear at some time or other, but mainly with good natural ventilation, and the lights off, or outdoors. You'll never know until it explodes, or turns your spray gun into a pressure jet burner.

How do I know? In a previous life I used to design and install explosion proof electrical installations.

[ethelred the ready]

How about using the fan to suck fresh air into the booth, that way only fresh non flammable air possess over the motor. The positive pressure in the booth would exhaust fumey air through a passive vent to outside
Might try making one myself, just got to mot van first...

[boatbuilder]

If you did it that way the intake air would be moving at a high speed so you'd need a decent filter at the fan to avoid dust getting sucked in.
I was considering just using a few tack cloths taped together as a type of intake filter.