Purchasing: Laser fume extraction pipes
Lex Bailey
Miki Mokrysz
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Lissa Moriarty
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John Cooper
Seems reasonable.
Do we want a one-way flappy thing on the outside so that the freezing
air from the outside does not drop directly into the back of the laser
cutter and onto the water filled tube when it's not in use? Or maybe a
valve in the ceiling that is interlocked with the fan?
"Metal Back Draught Shutter Damper, Spring Loaded Non Return Valve Backdraft Duct"
https://www.ebay.ie/itm/255271428161
john
> Hi all,
> Wow, a second purchase request in one night!
>
> The smaller laser cutter now has a new tube in it.
>
> Unfortunately we can't use it yet, because there's no fume extraction. We are going to put a hole in the ceiling to fit a pipe for extracting the
> fumes out one of the side windows hidden on the other side of the ceilings.
>
> That means spending money.
>
> Approximately £42.
>
> Assuming that the price does not change between now and buying it, we'll be spending exactly what's shown below...
> That's 3x 1m lengths of 100m plastic pipe. Four 45 degree bends (avoiding 90 degree bends for better air flow) and two couplers to join the
> pipes together.
>
> I can collect these from screwfix as soon as this spend is approved, and then shortly after that we can laser cut again! woohoo!
>
> Thoughts/approvals/grumpiness welcome.
>
> thanks
> Lex.
John Cooper@choffee
Lex Bailey
Lissa, your description of the plan is pretty much exactly what we're doing. I don't think we should put the fan in the roof space, at least not now, maybe in future. it's just a lot of faff, and if we're gonna need a bigger one later on that's capable of doing extraction for several things at once (two laser cutters and solder fumes) then we might end up undoing it anyway. This is very much "let's get at least one cutter working asap" kind of thing.
John, your suggestion of the back draft limiting flaps seems very sensible. anyone object if we bundle that in with this purchase too?
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Nat Lasseter
Gavin Atkinson
Lissa Moriarty
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Gavin Atkinson
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John Cooper
The current one looks like a bathroom fan for inline. These are
different from the wall fans. Most wall fans can't push air down
pipes and expect to have open back and front. There are some more
expensive ones that are designed to deal with the back pressure.
A flappy vent on the outside would reduce the draft and I think
would probably be the best option for a start. I'm also worried
that when it freezes outside the loft will probably be that cold
as well and so the air will drop down the tube into the back of
the laser so a vent to prevent that might help. ( General frost
protection in the space is another thing to consider but maybe not
here. )
I think the fan we have will be fine and probably okay in the
loft space as that's where it's designed to be. It might be
simpler to have it inside but it might be a bit quieter in the
loft.
For the second laser would we have a second fan/pipe or are we going for a shared pipe/fan. In which case a stronger fan might be required to pull from both at the same time.
I'm happy to go ahead with Lex's suggestion with a flappy outside
to get us started with what we have as it can all be used.
john
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David Newton
Good evening.
I’m not a member, but hope to be soonish, so am on the list. As I’m somewhat familiar with air movement perhaps I might clarify a couple of things.
1 – you need an inline fan such as this (https://groworks.co.uk/products/krystal-dual-speed-fans?variant=39407027159084) It’s 125mm dia and dual speed. What this means is that you’ll not need to change it to when you add one or two other pieces of kit to it. Use it with 125-100mm reducers.
2 – commonly brown 4” underground drainage pipe is used as the system back bone as it restricts flow least PLUS it stops material build up inside. Further it’s demountable for cleaning. Make sure all ends are cut perfectly square so as to reduce places for rubbish to accumulate.
3 – as you build the system up, maintain the 4” to the last couple of feet & then drop down to a minimum of 50mm pipe but always smooth bored.
4 – as you build up the system make sure all ends NOT being used are sealed off with say a bung otherwise performance will be severely compromised.
5 – Mount the fan so it is easily accessible and demountable. The fan will need a thorough clean every once in a while to maintain performance.
6 – lastly, make all bends in the 4” pipe 2 x 45deg elbows and in the flexible ends ‘long’ radius bends. Again these restrict flow far less and maximise performance.
7 – the spring operated anti-back draft valve is a good idea but put it just before the pipe goes into the final terminal. If you can, increase the terminal to a 125mm one. That will again reduce flow resistance. The ‘flappy’ version is NOT need due to the internal shutter above UNLESS it terminates facing the prevailing wind. If it does then go for a cowl such as this (https://www.i-sells.co.uk/system-150-white-cowled-outlet-with-non-return-flap-150mm-round-spigot?msclkid=33cbf4e70fb81c85869792eeed1dd495)
This lot may be slightly more as a spend but overall you’ll spend less as you’ll not need to replace anything. Just add as its needed.
David
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