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  1. #16
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    Quote Originally Posted by BobL View Post
    If it's too thin and flops around it will rob air flow and you may be better off replacing it with rigid PVC or stiff flexy.
    Instead of cutting the duct to size I ended up collapsing it entirely from 6m to about 30cm, which is the total length from the fan to the outside mesh, so now the duct is pretty much all collapsed wire and solid.

    Anyway after trying to find the least fussy mounting solution I could think of, and after battling a few hours with the multitool, this is what it looks like (sorry about the terrible photo)



    All it is some construction pine diagonally across the ceiling and some ply screwed on the wall with a 200mm hole in it to pass the duct.

    Basically the whole thing hangs from 2 screws but it runs so vibrationless and smooth that I think it's fine.

    In terms of suction, I struggled to open the door so I guess it does pull some air out.


    I don't know what it does about the dust but when I opened the window it made a very pleasant breeze in here so I really enjoyed that

    But I ordered the 5003 unit last night and I'll have an indication soon, I'll touch base then.

    Thanks again!
    SP

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  3. #17
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    My device arrived today.

    This is the first reading from the shed:




    I let it settle for a few minutes, it didn't change much from that.

    Then I put my mask on and did my worst

    I put a few pieces of MDF and hardwood through pretty much every powertool I own, stopping every couple of minutes to take a reading.

    Then I blew all surfaces with compressed air and vacuumed the floor, as I'd normally do.

    At that point it was pretty much a gas chamber in there, I could literally see dust suspended in the air.

    I left the shed for half an hour to have dinner, and then came back and took a couple more readings.

    Then I cracked the window open and started the fan.

    This is what the readings looked like:



    Basically according to this device it took the fan about 5 minutes to bring the dust content back to normal.

    Which makes sense because the shed is really small, and (if the cfm rating is correct) this fan should need less than 2 minutes to replace all the air and it's contents with fresh air.

  4. #18
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    Well that seems to be a success and a good example of what a decent exhaust fan can do.
    BTW for those detectors you need to double the readings to get closer to the right answers but that does not change the outcome of the test.

    Here is another example of an exhaust fan in action.

    It happened to me yesterday when I was welding up a small bench from some galv 40x 40 x 4mm SHS, mostly under my welding bay exhaust/fume hood.

    Welding is notoriously dusty - way dustier than people think.
    When Stick welding, flux is the prime culprit as it generates significant fine dust/fumes, and even fluxless welding like TIG generates dust and loads of noxious fumes like NOx and CO, plus SS welding generates Cr oxides.

    Welding galv generates large amounts of ZnO and although it can literally "take your breath away" and constant exposure can lead to a condition called "White Fume Fever", it only lasts for a few days and then the symptoms disappear. This can makes it a sort of semi-safe candidate to perform dust experiments. When Welding galv I usually grind away all the galv from the outside of the SHS weld joint area so that it generates minimal ZnO dust. However there is always some ZnO generated from the galv inside the pipe which I rely on the welding bay exhaust fan to remove.

    I started welding with the welding bay exhaust hood fan running and the dust detector located on a shelf about 2m above the floor and about 1.5m horizontally away from the fume hood. Initially the PM10 was at ~5 ug/m^3 rose to no more than about 15 ug/m^3. Some of the welds were performed outside the direct capture of the fume hood whereby some of the flux and ZnO fumes evaded direct capture and rose up to the ceiling and made its way to the dust detector. At these times the dust detector measured ~50 ug/m^3 for PM10 but over about 2 minutes it dropped back to <10 ug/m^3.

    After completing about half the welds I realised that there were 4 weld locations where I had not ground the galv away from the weld area but decided that I would weld those anyway. Two of these 4 welds were not inside the welding bay exhaust hood and I watched the dust monitor reached 485 ug/m^3 about a 30 seconds after completing these welds. It took ~2 minutes to bring these high dust levels back down to <50 ug/m^3 and about another 5 mins to bring it back down to <10 ug/m^3.

  5. #19
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    Quote Originally Posted by BobL View Post
    Welding is notoriously dusty - way dustier than people think.
    When Stick welding, flux is the prime culprit as it generates significant fine dust/fumes, and even fluxless welding like TIG generates dust and loads of noxious fumes like NOx and CO, plus SS welding generates Cr oxides.
    I know Bob, my father in law was a welder and he died early of lung cancer. He was mostly working in his 4 car garage at home, and there was no dust extraction or ventilation to speak of. Hard to prove causation with these things but it was clear he had no idea about the hazards, or at least about the magnitude. I think most people of his generation didn't.

    Anyway I'm very very happy with the results and I'd like to thank you again! I'll still wear my mask when making dust and for a (to be determined) number of minutes after, and I'll keep an eye on the dust monitor to get a better idea on how dust behaves in my specific set up. I had pretty much given up on the dust issue and it would never cross my mind that I could do something so impactful with such small footprint in the shop. Never mind quickly and cheaply.

    More people should know about this, a lot of guys work in small spaces and on tight budgets and have also given up. I don't know if you realise just how intimidating proper dust extraction can be, even taking proper readings and assessing them correctly is a whole chapter, even determining which particles are the dangerous ones is a moving target. It seems to me very possible to get fooled into thinking your system is all sorted, and then find out years later in the worst possible way that it really wasnt, because of some obscure bottleneck somewhere. Airflow and dust are complicated things.

  6. #20
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    Cheers Spyro.

    I don't know if you realise just how intimidating proper dust extraction can be

    You are right - I have to keep reminding myself I started thinking about and experimenting with ways of improving air flow and reducing/eliminating dust in the early 80's at work when we set up our first dust free labs. It only took me about 20 years to connect the "dust and airflow management" at work with wood dust making activities after I lost my sense of smell for 6 weeks after 3 days of working with MDF outside my shed. Even then it took me another few years to start testing actual wood dust making activities.

    Anyway I look forward to seeing what you can report on. Even if it is just what the dust levels are like after a couple of hours of "actual work".

    One more thing, post any results here
    http://www.woodworkforums.com/f200/dust-sensor-measurements-post-results-222282 so they are all in one place. It would be useful to at least post something in that thread about your test above even if it is just a link back your post above.

    Which reminds me I should put my welding test results up in that thread.



  7. #21
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    Done.

  8. #22
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    Hi Spyro,

    Can you post what the noise level of the unit is like?

    My "shop" is a garage in an apartment block shop I have top be very conscience of not upsetting the neighbours, especially in the evenings which is when I get most of my woodwork time.

    Many thanks,

    Adam

  9. #23
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    Quote Originally Posted by taz01 View Post
    Can you post what the noise level of the unit is like?

    My "shop" is a garage in an apartment block shop I have top be very conscience of not upsetting the neighbours, especially in the evenings which is when I get most of my woodwork time.
    The noise levels are shown here, scroll down to see the rated dB noise levels
    https://www.ebay.com.au/itm/10-INLIN....c100752.m1982

    They have to be quiet as they are popular with the "grow you own" community.

    BTW for reference a budget level bathroom exhaust fan is 48dB and a quality fan will be <40db BUT you might need to use 3-4 of these fans to match the flow produce be the centrifugal fan.

  10. #24
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    The noise in the shop or from the outside? From the outside it's negligible. It sounds a bit like the humming of those new gas heater units.

    I have a noise measuring app on my phone, I'll check when I get home tonight.

    Sent from my SM-G955F using Tapatalk

  11. #25
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    It's ok, the graphs that Bob pointed out are more than good enough.

    I could see that venting out a hole above the garage door but I'm unsure how to proceed with getting the fresh air into the garage. The internal entrance from the garage to the building I normally keep closed to minimise noise.

    Would it work if I put the impeller in the middle of the garage, the outflow vent above the garage door on one side, with an inflow vent also above the garage door but on the opposite side? I know it's not ideal but my options are limited.

    This would only be for handtool use as power tools are used outside.

    Sorry for the minor thread hijack.

  12. #26
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    Quote Originally Posted by taz01 View Post
    I could see that venting out a hole above the garage door but I'm unsure how to proceed with getting the fresh air into the garage. The internal entrance from the garage to the building I normally keep closed to minimise noise.
    You could put a vent on the internal door.
    Better still you could put an S shaped noise trap/baffle attached to the vent on the door.
    This shows a multiple S shaped baffle noise trap for a DC enclosure but the same principles apple.
    The orange padding is some form of foam rubber.
    You could probably get away with just one S bend.
    Bafflebox.jpg


    Would it work if I put the impeller in the middle of the garage, the outflow vent above the garage door on one side, with an inflow vent also above the garage door but on the opposite side? I know it's not ideal but my options are limited.
    Sorry no this would not work - unrestricted direction of fine dust is like herding cats - all this would do is distribute the fine dust all over your shed. Rae air/dust need to have a positive constrained directional flow (preferably at source) to be effective if not alt least so as the air/dust is exhausted with minimal chance of it circling bak inside the shed

  13. #27
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    Quote Originally Posted by taz01 View Post
    Sorry for the minor thread hijack.
    no problem whatsoever.

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