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  1. #31
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    The floors are sanded and sealed and we're just waiting for them to harden up a bit. Meanwhile I'm tackling the short flight of 4 stairs between the kitchen and family room. The floor sanding man wanted much more to do these than I was prepared to pay so I said I would do these myself.

    Now that I have rough sanded two of the 4 steps I can see why he wanted so much. It's taken me about 3 hours to setup and and rough sand 2 of the steps and now I am pretty stuffed so am taking a break. Admittedly the sanding man has much HD sanders than I have (6" Festool ROS and a Ryobi mouse sander to get into the corners) but I can see this is going to take all day - not that I have anything else to do of course The hardest part is doing the vertical faces, and the edges and corners where the previous finish seems to have pooled thicker than elsewhere and of course not worn away.

    Anyway with plenty of dust detectors to play with I have swung 2 into action to see what is going on.

    Here you can see the setup at the stairs with a Dust detector over at the side.
    I have just about finished the rough sanding of the top step.
    The rough sanding is being done with 80grit paper.
    The sanders are connected to a Ryobi W&D Vac out in the laundry by about 4m of hose.
    The Ryobi's outlet (the benefit of a W&D vac ) is then vented by a 5m hose outside through a doggy door.
    When sanding with the sanders the dust sensor detect no more than about 6 ppb (nominal OHS is 500 ppb) of dust.
    Hand sanding with 60 grit paper with the running vac hose nearby produces about 10 ppb of dust at the sensor.

    IMG_2709.jpg

    Here you can see how far it is to the Ryobi in the Laundry.
    One hour later have now rough sanded 2 steps - might have to get the Makita belt sander out!
    IMG_2710.jpg

    In the laundry a 2" hose from the vac outlet snakes through to the back door and out a doggie door.
    There is also a running bathroom type extraction fan in there as well.

    IMG_2711.jpg

    I placed a second dust sensor in the laundry to see what is escaping from the vac and also coming from the Vac motor cooling loop.
    the highest I've seen this go is to 24 ppb - it could have gone higher but that's all I have seen - its being recorded so I can check back later to see if it has gone higher.
    Some of this is dust from the fabrics etc in a laundry but more than 3/4 of the 24 ppb is coming from the vac.
    With no sanding dust being collected the amount of dust coming direct out of a clean (blown out with compressed air) Vac motor cooling loop is around 40 ppb.

    IMG_2712.jpg

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  3. #32
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    What filter type are you using in the vacuum Bob?
    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

  4. #33
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    Quote Originally Posted by rob streeper View Post
    What filter type are you using in the vacuum Bob?
    Standard paper cartridge.
    Remember in this setup anything that gets past the filter is all blown outside

  5. #34
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    More sanding of the steps the morning.

    I brought the Makita belt sander into action, and this time I also wore the wearable dust sensor.

    Today is a lot more humid than yesterday so the ~10 ppb apparent dust back ground was much higher than yesterdays ~2 ppb.

    The belt sander made short work of stripping the bulk of the old finish from most of the steps so it only ran for about 10 minutes generating between 25 and 50 ppb of dust at the wearable and between 20 and 30 at the sensor over on the side of the room.

    The belt sander is just too big to get to the edges and corners and cannot even fit onto the riser (not even the Festool ROS 6" pad will fit on the riser so its back to the Ryobi Mouse and hand sanding for those. While using the ROSs , the wearable reported between 20 to 35 ppb (yesterday it was 6 ppb over on the side of the room) which shows why the wearable is more realistic.

    All the dust readings are well within the safe zone which I think reflects the use of a fully venting vac in this situation.
    [ADDENDUM]
    This after noon I finished the stripping with 80 grit and then moved onto the 120 grit with the ROSs and hand sanding and got similar dust concentration readings as for the 80 grit

  6. #35
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    Great info, the thing that annoys me, and it's my problem though, I'm one of the unlucky people that anything over around 25 PPB, depending on the irritant, causes my sinus to block or I feel hay-feverish. Like I said before, I can't even visit a men's shed for more that 10 minutes (without a mask), yet mowing lawns, clipping trees, being covered in pollen etc has no effect, a wood fire and I'm out of there. The fact that I can spend all day in our WS using machinery without a mask is something I though would be impossible, all because of these threads and heading down the right path to finding something that works for us, even within a tiny budget.

    Thanks for all the work Bob and keep it coming for as long as you feel the force

  7. #36
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    Quote Originally Posted by MandJ View Post
    Great info, the thing that annoys me, and it's my problem though, I'm one of the unlucky people that anything over around 25 PPB, depending on the irritant, causes my sinus to block or I feel hay-feverish. Like I said before, I can't even visit a men's shed for more that 10 minutes (without a mask), yet mowing lawns, clipping trees, being covered in pollen etc has no effect, a wood fire and I'm out of there.
    Some woods seems to bother me more than others, eg I've been sanding these Jarrah stairs all day with up to 50 ppb exposure no immediate problem.
    Even milling in a fog of 100 year old Jarrah sawdust does not seem to cause immediate problem.
    I do have a full face Triton air make for this sort of work - just didn't have it with me when I did the milling.
    reddust.jpg faceshield.jpg

    It would be very different if it was MDF or WRC.

    My most sensitive symptom is asthma which I have only developed recently. I can tell that there is burning off in the Perth Hills long before I see any smoke. Grasses and pollens generate a mild reaction and there are couple of vines down the side of the house that come over from the neighbours place and form a dry tangled mess that gets up into our roof space. These set me coughing and spluttering after I cut them down and generate a bunch of dust.

  8. #37
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    Here's some dust data for a Men's Shed just outside a small town in the lower coastal South West WA.
    The shed stands unprotected by vegetation and there are no other buildings close by.
    The coastal sea breeze is pretty regular and relatively strong compared to most other sheds

    The shed is quite large - must be at least 15 x 25 m and is divided into a number of sections/rooms. The main WW area is probably 12 x 15 m.

    The photo shows the west end of their main WW space - lathes and some other machinery are in an adjacent room.
    There are large sliding doors at each end of the WW section and another large sliding door into the MW section so there is decent ventilation going through it most of the time
    The red oval in the picture below shows where the sensor is located - I would like to have gotten it lower in the shed but I worry about it getting damaged.

    CMS2018.jpg

    They are planning to install a fully ducted system and a DC that vents outside the shed but currently they have 3-4 conventional DCs located inside the shed and only used 100 mm ducting between machines and DCs.
    Admittedly their member attendance use while the data was being collected was below average but given their situation I was still pleased to see the low concentrations.
    We are collecting data more data over teh coming weeks so it will be interesting to see what happens when membership attendance gets back to normal.


    CMSDataJan2018.jpg

  9. #38
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    Is there any difference in activity type during the times that I've highlighted below in your plot? i,e., machines off or different types of machines in operation?

    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

  10. #39
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    Quote Originally Posted by rob streeper View Post
    Is there any difference in activity type during the times that I've highlighted below in your plot? i,e., machines off or different types of machines in operation?
    There was probably no one in the shed at those times - the shed is open from about 8am to 5pm but hardly anyone turns up until 9am and by 4pm most members have gone. There might be members at the shed but in other areas of the shed eg metal work or automotive repairs but these take place in other rooms.

    The next thing is that I don't place much meaning in data of <1 ppb. I really should run the long term smoothing averages for longer when the data gets down to that level.

    Secondly, concentrations less than about 10 ppb are most likely all due to natural background. The nearest AQI station to that mens shed is in the town of Busselton (~20,000 people) people and it has an annual average PM10 concentration of 17 ppb which is the same as nearly all towns on or near the west coast of Western Australia. The mens shed is in a village some 40 km away from Busselton and it has <1000 people with only farming as its surrounding industries. I would guess their long term PM10 background would be around 10 ppb

    Long term (30 minutes +) variations in the background will be temp/humidty related. Shorter term variations will be causes by variations in wind of varying speeds speed going past the shed and maybe occasionally moving some dust around inside the shed?

    [/QUOTE]

  11. #40
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    Hi Bob, a quick off topic question. Do you know if the following sensor would be capable giving meaningful readings of volatile organic compounds when cutting / sanding MDF? If not, do you know of one that could? Perhaps it's not worth the effort but thought I'd ask anyway.

    The CCS811 provides readings for equivalent CO2 (or eCO2) in the parts per million and total volatile organic compounds in the parts per billion.

    https://www.littlebirdelectronics.co...t-ccs811-bme28

    Mike.

  12. #41
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    Thanks for the lead on this one Mike, I have not seen it before.

    I chased up some additional info and found the BME2 sensor details here https://www.bosch-sensortec.com/bst/...roducts/bme280

    The CS811 sensor details are here CCS811 / Air Quality Sensors / Environmental Sensors / Products / Home - ams AG

    The PDF data sheet says it picks up Alcohols, Aldehydes, Ketones, Organic Acids, Amines,Aliphatic and Aromatic Hydrocarbons .
    No conc data is provided but on this page https://www.tindie.com/products/oneh...ality-sensors/ the range claim is 0 - 1200 ppb but no accuracy specs are provided.

    The basic MQ138 TVOC sensors use the same metal oxide type based sensor as the CS811 and cost a bit less (~ $20, $40 in a basic package) but you then have to add on and perform HT corrections yourself.
    The humidity compensation required for TVOC are not that high, between 35 and 85% Humidity is around +/-5% and the temp effect is also ~ +/-5% between 10 and 30 ºC.
    The MQ138 appear to work up to a much higher concentration range (10,000 ppm for benzene, methane, alcohol and hexane, no range given for formaldehyde) than the CS811 but if you start to see 1000 ppm TOC in air and didn't have a good reason ie methanol vapour you'd want to know what is going on

    I reckon they would be worth a go especially given the inbuilt compensation provided by the BME2 HTP sensor.

  13. #42
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    Doing some Al TIG welding this afternoon and had the radio on, plus the welding unit itself has a fan in it which makes a fair bit of noise.

    The welding runs were short (4 x 20 mm long each) and after finishing these (ie <5 minutes given I had to reposition the work between each run) I flipped the helmet up to check the welds and could see a very faint haze in the shed air and realized I did not have any dust/fume extraction on. Looked over at the particle counter some 4m away and sure enough the PM10 dust concentration was over 500 ppb! Remember this is TIG welding - no flux on the welding rods - it just bare Al metal workpieces and rods.

    The dust is almost certainly Al Oxides and organic crap on the Al, I clean about 20 mm either side of the weld with a sander and dedicated wire brush but the whole workpieces get very hot and the metal did have texta marks on it and some adhesive and oil on the back of the work.

    PM1 was 278 and PM2.5 was 420 ppb

    I don't like deliberately contaminating the shed to test dust extraction but this "accident" gave me the opportunity to do it from a contaminated state. Turned one everything I had available exhaust wise, Welding fume hood fan to max (~1600CFM), the central exhaust fan (1200 CFM) and the DC with about 3 blast gates wide open. (>1000 CFM) and the particle counts were down to the same as external shed air after about 3 minutes. This is similar to what I have seen for wood dust

    What is interesting is the higher that usual amounts of PM1 dust compared to PM10 dust.
    When woodworking I typically see the PM1 : PM2.5 and PM 10 dust concentration in a ratio of 0.25 : 1 : 1.5
    ie significantly fewer sub 1 micron particles compared to the others.

    The welding dust ratio was 0.66 : 1 : 1.2 , ie ~2.5 times more PM1 dust than woodworking.

    This could be a due to a couple of things, eg the nature of the welding dust itself, but also it could be that it shows the fine dust just travels further/quicker. It could also be a combo of the two. Either way it shows how quickly it can happen.

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