12v dc extractor

Why on earth would somebody want a battery fan?

 

Yes. Try Maplin's (www.maplin.co.uk). They have a number up to 5 in dia for less than £10.

 

Why on earth would somebody want a battery fan?

Boat, Caravan?

 

Check out fans made for electronic equipment - they may well work off ELV DC supplies.

 

The fans used in PC cases run off 12V DC, the main sizes are 120mm and 80mm. They're designed for fitting into a case so if you wanted to use it as an extractor fan you'd need to buy a couple of finger guards and build a mounting for it. That's assuming it could cope with the enviroment you're using it in - I doubt they're as resistant to humidity as a proper extractor, they should handle dust ok though. Also bear in mind that air flow will be lower.

You should be able to get them from any decent PC component supplier. To give you an idea of the cost - Ebuyer do an own brand 12V DC 120mm black case fan for 82p, a 120mm stainless fan guard to fit over it will cost you 17p. Probably worth paying a bit more for a branded one though, oh if you're concerned about the noise there's a lot of low noise/silent fans available now that more people are 'modding' their PC systems.