Setting up "proper" fume extraction?

[justin1985]

I'd like to install some proper fume extraction in the space I use for modelling, but don't really know where to start with ductwork and fans. 

 

The space I use is an integral garage, entirely within the footprint of my terraced house - the only outside "wall" is the wooden up and over garage door itself (which is very seldom opened and now hard to open, making it even more seldom opened ...) with very minimal brick columns either side (one a party wall, the other wall with the hallway/porch). Therefore, it seems like some kind of temporary, or at least temporarily movable, connection through a hole in the door itself will be the only option?

 

A complication is the fact that my workbench, and where I tend to have other machines etc set up, is at the furthest end of the garage from the external door. That is where the electrical sockets are all located, there is much better lighting, and it is relatively safe from dust that inevitably blows in around the up and over door, despite draught excluders. So I'd prefer to have some kind of ductwork rigged down much of the length of the garage - otherwise I'd have to rig up another workstation of some kind, with electrical supply and lighting, at the far end. 

 

I've got an airbrush (which I either try to use outdoors when the weather is good enough, or only briefly, using a 3M respirator before ducking out of the garage while things settle) as well as a resin based 3D printer (which stinks quite badly when running) and now also a small diode based laser cutter (only really used to cut small amounts of card etc so far, but would like to cut more acrylic etc, which would release even more harmful fumes). So I'm looking for a flexible extraction system that could work for all of these. 

 

What should I be looking to get? Especially in terms of diameter of ducting, type of ducting, and power of fan?

 

I imagine I'm looking for some kind of slot in/slot out fitting to mount on the door, with one of those flappy outdoor covers (hopefully available in brown to match the wood) - would the type sold for tumble dryers be good for this side of it? 

 

If I did want to run the ducting from the "workbench" end of the room down to the external door, I imagine I'd need some combination of rigid ducting (steel?) for the long part of the run, and something flexible to connect both ends. I imagine the flexible ducting varies quite a bit in quality - what to look for?

 

And I imagine I'd need an inline fan - presumably one in the back of a hobby grade portable spray booth type thing (or repurposed kitchen extractor) isn't going to be much use at all if there is any kind of distance to cover? What kind of power / spec would you need for it to be effective at shifting paint fumes or smoke from a laser etc?

 

Many thanks for any tips!

 

Justin

[wirey33]

I have a sort of similar extraction situation....

 

The rules and regulations state that I need an extractor fan for the room (it's in a cellar) and in addition, I have had a outlet pipe (4"/100mm) incorporated into my house build specifically for spray-booth extraction.

 

Mine is directly above my work bench, so I won't have the problems of distance that you will. I have purchased some aluminum flex hosing that would be used for a tumble dryer and I'll use that to go from the back of my spray-booth to the outlet pipe. I seem to remember that the hobby spray-booth fan was actually more powerful than a typical bathroom extractor.

 

Would you be better off with an industrial extractor/filter on a trolley? There's probably some hobby versions available for welding?

 

 

[SP Steve]

If extraction of flammable vapors are a possibility then you really ought to use a squirrel cage blower / extractor unit such as this:

 

https://www.amazon.co.uk/SSCYHT-Extractor-Centrifugal-Extraction-Ventilation/dp/B09FQ3MGML/ref=sr_1_4?dchild=1&keywords=squirrel+cage+extractor+fan&qid=1631282398&sr=8-4

 

On these the extracted air is not exposed to the electric motor thus removing a possible safety issue whereas the normal bathroom type extractor fan has the fan motor within the extracted airflow.