I am now fitting out my new workshop. I have a 14" extractor fan, I intend to fit a plpe feeding in to it with the other end fitted with a flexible hose to slide over car exhaust to prevent fumes building up. Any ideas on what material the hose should be made of or any better ideas for extracting fumes.

I've been reading up on spray booth extractor systems today (it's been a slow month) I would also recommend getting a fan to bring in fresh filtered air from outside as well as an extractor fan. It will serve a few purpose's one it will replace the air that the extractor fan will take from the workshop, two it will help the extractor fan be more efficient by diluting the fumes and thirdly it will act like air con in the summer.
As for tubing it depends how clumsy you are and how durable you need it to be, exhausts not only get warm to the point of melting thin plastic but they also produce water.

I recently rigged up a simple exhaust fume extraction pipe. 1st 18" is exhaust flexible tube the rest is 2.5" plastic plummers pipe. No fan.

Works a treat for me in my single garage. Duck tape up the joins and keep a door open!!

Thank you both for the replies, I like the idea of two fans, with regards to water it would only be for short term running so should not pose a problem.

With regards to you looking into spray booth extraction, my painting is restricted to just small areas such as boot lids, doors etc. Finding commercial fans very expensive, but realising that the motor should be fully enclosed for safety reasons I bought a 14" motorsport rad fan off the internet, it is fully enclosed for weather proofing and it cost £12 new. It seems to work well, just an idea for you.

I bought a 10m length of twin wall spiral aluminium flexi-ducting from Screwfix or similar, like_this, it was not that costly. I fabricated a couple of bits of aluminium, one for the hot end with a single screw to hold it on the exhaust return, and the other end with a hook on it so I could hang it up outside above the roof line.

The 10m was advantageous for getting the fumes as far away as possible so they didn't just linger about

No fan fitted, but it seemed to work ok.

I did some silver soldering that involved cadmium so rigged up a 10" wall fan and some ally duct from B&Q.
It was labled as tumble dryer vent, but same as eBay Item

In my case the fan was in the end wall apex and the pipe dangled over the bench. Worked well; must have done as I'm still alive.



Just to state the obvious, if working on fuel/carb/air filter set-ups then a fan with extra suck is needed and a big duct that's a
loose fit over the exhaust. The engine fume plus a bit of extra surrounding air is then "sucked & chucked" without affecting any settings.

Cheers,
Paul G

Not sure what is used, but a couple of rolling roads I've been to have had extraction pipework. I suspect they have flexible exhaust hose to deal with any heat issues and it might be worth looking at workshop suppliers to see what's available. Speaking to a good rolling road might also be helpful.

I've considered fume extraction in my garage, mainly to remove welding fume rather than breath it in. My garage is also integral to my house so it would help keep it out of the house too. As above, I suspect bringing filtered air in and expelling fume is the trick to get it right.

A quick Google threw this up - might help narrow down what you need?

http://www.autoextract.co.uk/p/motor_sport_fume_extraction.php

Car rad fans, some hardboard and make them to fit in an opening window. Works brilliantly. Need a decent old style type battery charger to work them.

I built a wind tunnel about 30 years ago to conduct some experiments. There were 4 mains power axial fans that provided the starting wind speed, and then a single rad fan on a variable 12v supply that gave the adjustment.

I have never worked out how much air it shifted, suffice it to say that the rad fan on full was too much,. some 22 m/s of wind in a tunnel about 1m x 1m,...

It's worth remembering that a 2L engine running (for test purposes) at 6000rpm produces 6000 litres of exhaust gas.
Whatever fan is used must be able to keep up, and more besides.

Paul G

This is the most common system used in actual workshops to give you an idea what to aim for.

http://www.nederman.com/products/exhaust-extraction


But it would be worth having a CO alarm in the garage just to make sure that what ever you have is actually working.

I have seen ducting built with the metal spiral ducts like this,
http://www.ductstore.co.uk/index.html

They also do inline fans.

[Edited on 20/1/16 by DW100]

Thank you, all of you, for your helpful information.