Thread: Dust Exposure while empty DC bags and cleaning filters

I've been meaning to empty my DC bags for a while now and this time I thought I would wear my wearable particle counter to assess the sort of exposure one might undergo while empty DC bags and cleaning the filters. One bag was about 1/4 full and the other was about 1/3rd full.

For those that don't know or have forgotten about it I made the wearable dust particle counter/detector back in 2017and can wear it on me while doing woodie stuff. This provides a much more realistic exposure as the detector is located as close as possible to the operator's cake hole.
Wearable.jpg
For more grimy details Developments in Dust Sensor tech

This detectoruses a small version of the Plantower 7003 counter (A003) connected via blue tooth to a microcontroller that records the data and this usually sits on a bench over on the side of the shed plugged into a wall socket while I go about my activities. In this case as I was going in and out of the shed and from the front of the shed to the back I wore a small backpack and had the micro controller and USB battery power inside the backpack.

I should also add I normally wear a Triton full face helmet/mask while doing emptying teh DC bags but my bro has borrowed the Triton so I just wore a P2 mask.
There was a nice gentle breeze blowing so where possible I tried to keep my back to the breeze at all times.
Nevertheless I was still covered in fine dust when I finished the job.

The process basically involves,
1) opening DC enclosure - its pretty dusty in there I've never cleaned it since I built it 9 years ago.
2) shaking filter bags in situ for about 30 s each to get most of the fine dust on the inside of the filters down into the plastic collection bags
3) removing plastic collection bags and dumping the contents into the green bin
In the photo below you can see how much Aluminium I cut.
sawdust.jpg

4) Remove filters, invert then and shake them out in the garden about a dozen good shakes - its pointless getting them super clean as they get dirty again really quickly
5) Hang filters up and bash them about 20 times with a piece of 3 x 1.
6) Brush any remaining large stuff still clinging to inside of filters using a soft wire brush
7) replace everything.

Here what the filters look like before brushing
dirtyfilters.jpeg

And after
Brushedbag.jpg

And here is the exposure over time of the whole process.
The vertical axis is dust concentration in µg/m^3

CleaningDC.jpg

"A"represents me getting organised and leaving the particle counter in various places to get background readings, eg, at the back of the shed where the DC enclosure is located, the inside of the shed, and the front of the shed where the bag emptying and filter cleaning was going to be taking place. Except for the first count which is the counter clearing itself the PM10 and PM2.5 dust levels were all well <10 µg/m^3 which is normal for these places.

"B" is where I was shaking the filters to get most of the dust clinging on the inside of the filters down into the collection bags.

C and D was where I removed the plastic collection bags and emptying their sawdust contents into the green bin. Big wafts of dust came out of the bin at those points these are the highest exposures during the whole process. On reflection I was not standing upwind when I the dumping and this was almost certainly when I copped most of the dust onto myself.

E was when I was removing the filters
F - G was when I was inverted the filters and shook the dust into the garden
H was when I was brushing the filters with the fine wire brush
I was putting everything back together and
J was the dust levels in the area where I had shaken out the bags - it looked like the breeze had brought the levels back again to where they were to start with.

The green line represents the long term levels PM2.5 levels recommended for seniors or people with health conditions. As you can see there were only 2 points during the whole process where it exceeded this level.

Specific exposures during this process would depend on what type of dust has been collected. In my case most of teh sawdust would have been coarse dust (TS and Thicknesser dust) but there was still a significant amount of belt sander dust in there as well.

So it looks like emptying the bags and cleaning the filters is not that big a deal especially if like me you only do it every so often (In my case its months). Of course if you were doing it every few days or even weeks it's a right PITA and I'd be getting a cyclone.