Speedy 300 extraction, straight up through flat roof

[Robert E Mason]

Hi all,

As per the thread title. I'm in the process of buying a Speedy 300 and am planning out the extraction. It's going into an industrial unit in an industrial area so smell isn't an issue (others in same complex have paint booths etc venting through roof). 99% of my cutting will be acrylic (I make architectural scale models) but there will be some wood occasionally (thin veneer type).

My current and favourite plan is to run flexible 4" pipe out of the back of the laser on a very short run into an 8" Elicent fan (not cheap but noise level and longevity of the unit are important, I'd rather pay out more now and have it be the one rather than buy cheap and have to replace it too soon). The fan pulls 636cfm which is excessive but I will put a speed controller on it to drop that a bit which has a nice side effect of also reducing noise (the 6" only pulls 309cfm which I'm under the impression is not enough?). After the fan I will be running 6" metal ducting through a single 90 and then up to the roof (17'6" from floor to ceiling so about 15' run) then out of the flat metal roof (standard industrial type roof, metal sheet covered in osd, insulation and tar sheet with gravel chips), run 3' above roof line then a rain cap.

209552

Couple of question if you don't mind :)

1) Any major problems with the set up as I see it? (See drawing for a very rough layout)
2) At the roof point do I need to do anything with the pipe other than fix it with a metal flashing kit like those sold in Home Depot? I will be clamping the ductwork to the wall until it passes the roof of the mezzanine behind it.
3) Any comments or suggestions greatly appreciated.

Robert

[Scott Shepherd]

I don't see any issues with what you have. We do something very close to that, going out a flat roof.

[Craig Matheny]

All looks well the only thing is make sure to metal tape all your joints from the blower to the roof so you have no leakage into your room. Good Luck

[Joe Pelonio]

I had a similar setup in an industrial area, with 25 foot run and no problems. With metal ducting, use rubber in every place that it attaches to the building, or you will get noise from the vibration.

[Gary Hair]

I would highly suggest you put the fan closer to the exhaust end of the run. Ideally it would be at the very end, but with it being outside that may not be possible. The reason for this is because any leaks you have when you are blowing from the laser to the outisde will result in exhaust escaping into your work area. If it is sucking from the roof then all that happens is that air is drawn into the exhaust. It's possible that you will have a perfect seal on every joint, but not likely - why not eliminate the chance of leakage?

Gary

[Robert E Mason]

Thanks for the replies. I did consider putting the fan mounted to the roof to have all the positive pressure outside but wanted to avoid this to simplify wiring and also as there isn't anything up near the roof to fix the fan to, other than the roof itself. I was hoping that by properly taping every joint I could avoid the greatly increased difficulty of roof mounting (on a 15' run there would only be 4 joints inside the building after the fan ( fan to 90, 90 to tube then 2 joins on the 3 lengths of 6' tube, allowing 3' passed roof line).

Robert

[Mike Null]

Robert

Your installation is quite similar to mine though I have a shorter run and use a smaller blower. I am a big fan of in line blowers--mine is now 14 years old and as quiet and efficient as the day I bought it.

I would add a blast gate in the line probably near the laser.

[Robert E Mason]

Hi all,

Just an update. Extraction is in. After I bought the parts I went back to the original plan of having the fan up on the roof. The fan is rated at 579cfm but you just can't hear it, can hear air being sucked into the wye at the bottom but that's it. Compared to the stand alone extractors it's as good as silent.

Just need the laser to arrive now :)

edit: forgot to add, I put in some 2" pillow foam underneath the strapping. Was $6 from Walmart and has a good amount of give but was still well padded when fully compressed so isolates vibration nicely.

thanks again for the comments

210506

Robert