Air filter

[wallace]

Instead of capturing the fine dust particles why not just remove the air they are suspended in and replace it with new air. Have an extractor venting outside at one end of the workshop and air will be replaced which does not have the fine dust. Bearing in mind you are still breathing the same air as any filter within your workshop so unless your wearing a mask its pointless, unless you use it on a timer to scrub the air whilst your out. I used a car radiator fan from a scrap yard for a while to suck the air from my workshop

 

[Inspector]

Instead of capturing the fine dust particles why not just remove the air they are suspended in and replace it with new air. Have an extractor venting outside at one end of the workshop and air will be replaced which does not have the fine dust. Bearing in mind you are still breathing the same air as any filter within your workshop so unless your wearing a mask its pointless, unless you use it on a timer to scrub the air whilst your out. I used a car radiator fan from a scrap yard for a while to suck the air from my workshop

That is the best way especially in mild (yours) or warm climates (Aussies). Here though where it is below zero for 5 or 6 months at a time and below 20ºC for 3 months in a row it is less attractive, hence the need to capture it at source. I'm not well heeled enough to have a second place in a warm climate for the winters.

Pete

 

[Terry - Somerset]

I assume all the data on filter efficiency relates to new filters.

What I have never understood is the change in effectiveness as they age:

• I assume the flow rate falls as the filter becomes congested - but by how much
• I assume that with use dust particles clog the filter - by how much is the particle size trapped by a partially congested filter reduced

Intuitively these seem plausible outcomes - is it really the case.

 

[Inspector]

As a filter fills the flow drops until almost nothing flows through but the more dust in it the finer it filters. New filters need some time to "condition" and get a little plugged, which stays in the filter when cleaned unless very aggressive with the cleaning. Too harsh with the filter can damage it allowing more dust to pass through. On industrial machines they will have a pressure gauge (magnehelic gauges) set up to measure the back pressure of the filters and when there is a difference of about 3 inches of water column between clean and dirty it will trigger the cleaning cycle, shakers for bags and pressurized air blasts to momentarily reverse the flow in cartridge types. If you set up a similar gauge and check it you know when it is time to replace or clean them. You can use the simpler water in a U tube manometer arrangement.
https://www.dwyer-inst.com/PDF_files/004.005.d.pdf
Pete

 

[HamsterJam]

Instead of capturing the fine dust particles why not just remove the air they are suspended in and replace it with new air. Have an extractor venting outside at one end of the workshop and air will be replaced which does not have the fine dust. Bearing in mind you are still breathing the same air as any filter within your workshop so unless your wearing a mask its pointless, unless you use it on a timer to scrub the air whilst your out. I used a car radiator fan from a scrap yard for a while to suck the air from my workshop

Granted venting fine dust outside is an option and in summer, a very good one. However pumping warm air outside to be replaced with cold in winter defeats the purpose of heating and insulation so I plan to recirculate.
And yes, scrubbing the air overnight is on the agenda.

 

[HamsterJam]

On industrial machines they will have a pressure gauge (magnehelic gauges) set up to measure the back pressure of the filters and when there is a difference of about 3 inches of water column between clean and dirty it will trigger the cleaning cycle, shakers for bags and pressurized air blasts to momentarily reverse the flow in cartridge types. If you set up a similar gauge and check it you know when it is time to replace or clean them. You can use the simpler water in a U tube manometer arrangement.

A while ago, I worked on some plant which had significant cooling requirements. Outside Air was drawn in through a very large filter and the pressure drop monitored. When the pressure rose to a preset level the filter media was automatically replaced by a roller mechanism, unwinding clean media off one roll and collecting the dirty media on another roll. Once the roll was spent, it was removed and taken away to be cleaned. Quite impressive.

 

[Raymien]

Instead of capturing the fine dust particles why not just remove the air they are suspended in and replace it with new air. Have an extractor venting outside at one end of the workshop and air will be replaced which does not have the fine dust. Bearing in mind you are still breathing the same air as any filter within your workshop so unless your wearing a mask its pointless, unless you use it on a timer to scrub the air whilst your out. I used a car radiator fan from a scrap yard for a while to suck the air from my workshop

I don't heat the double garage I work in, and so this may actually be a suitable alternative option for me as I've not got heated air I need to retain inside. I mostly work with MDF, and despite having a dust extractor and wearing a mask I'd like to have cleaner air inside my workshop. Plus the layer of dust I have laying over everything is getting tedious, so an option to set a timer for it to clean up after I've left would be good.

I'm wondering if I could rig up a small scale extractor setup in the void amongst the roof trusses which ejects the air outside. Having 2 or 3 'vents' which 'suck up' the dust above the main locations I work is what I'm thinking. A part of my shop doubles doubles as a spray booth sometimes too, and so a vent above this area would help remove the airborne overspray too.

Would something like this in line fan be a suitable component? I'm guessing really, so any advice on the parts required to construct such a setup would be gratefully received!

 

[Inspector]

A moderator on another forum with more expertise than I advocates 20 air changes per hour. Assuming you have a decent size 2 car garage of 7.5M x 9M x 3M = 202.5 cubic metres x 20 = 4050 cubic metres per hour. Your fans would have to be sized to move that much air and you will need openings opposite them if possible to keep the air from taking a shortcut and leaving dead spaces. That would mean you would need about 20 of those little guys. Even if you went for half as much airflow you'd need 10. The fans used for barns or greenhouse ventilation are more in line for what you would need.

Pete