Home spray booth - fans, filters and 2K isocyanate fumes

[Jamieg285]

Still doing lots of reading, and have worked out what I am doing regarding 2K and air fed setup. Now my focus is on setting up the painting environment and sorting a temporary spray booth.

I want to set it up with fan(s) to help manage the overspray/cloud (as far as possible), but am looking for advice on choosing correctly.

I'm looking at a portable ventilator/fume extractor to pull the air out of the booth, but I'm not sure which type of filter(s) I need on it - concertina paper or fibreglass (or other). As far as I can tell, these are designed to capture the paint molecules from the air - does this mean it will capture the iso's, as from what I've read these are in the paint mist. If they aren't captured, what are the best options to minimising the fall out area? How far could the iso's get? Do they rise or sink. so do I vent up high, with a chimney, or down low? Would any additional filters help?

Then there is inlet air. I know this needs to be filtered too, and I guess this can be the fibreglass type, as it's only catching dust. Can the inlet just be a filtered opening, or is it better to have a fan pushing air in? I'm guessing the later, to help avoid too much negative pressure in the booth.

Any ideas/suggestions?

 

[the snooper]

A spray booth works on negative presure also you will need to move a massive amount of air if it is to work properly

 

[ford34/2]

Worth a read and remembering::

http://www.hse.gov.uk/mvr/bodyshop/isocyanates.htm

http://www.mig-welding.co.uk/forum/threads/2k-safety-leason-learnt.14051/

Stan

 

[RaceDiagnostics]

I think that most booths just vent the iso to the atmosphere, the filters capture the paint but not the iso. Some top end booths pass the exhaust through a gas burner to remove the iso.

I know there are a few spray booths within 20/30m of domestic residences in Dunfermline, I wouldn't be happy living that close to one.

I occasionally paint with Iso in my garage but only do it during the day, midweek when there is no one about as I don't want to poison any of my neighbours, and also my compressors sound like concord taking off and don't want an asbo.

 

[Parm]

Not for home use, but if you do make sure you tell all potentially affected neighbours that they are risk of inhaling something quite nasty.

In the industrial world isocyantes are usually discharged directly to atmosphere, however there are very strict permitting conditions usually set by the environment agency that require the height of the discharge stack to be calculated to ensure that the discharge point is high enough relative the ambient topography to ensure adequate dispersion of contamination.

2K stuff is so dangerous that in my opinion it shouldn't be sold unless you have specific training and all the correct kit.

 

[pedrobedro]

I think that most booths just vent the iso to the atmosphere, the filters capture the paint but not the iso. Some top end booths pass the exhaust through a gas burner to remove the iso.

That sounds like a recipe for an explosion. When I was spraying in the boiler factory the extractor was through a water curtain and a few other filters before venting outside. It was not 2k system but the amount of solids in the filter was something to see.

 

[steveo3002]

is this for a one off home job? it takes some massive fans to have any effect on clearing a booth , if its just a one off i would break the job into smaller sections and put up with the cloud

 

[dannyp]

a few years ago i looked at building a spray booth with a mate, to do it right you need quite a lot of power. we never finished it never even used it as we never sorted the heat side of things out.

the booth exhaust fan in the end ended up with a 3 cyl kubota diesel engine to run it. the plan was for a negative pressure booth, and use the pressure diffrence to draw air in through some radiators ( party heated by the engines coolant and a massive billy bodgeit wood burner ) then through the filters, useing 1 big exhaust fan. seemed like a good idea but it didn't really ever work

 

[anjum]

I occasionally paint with Iso in my garage but only do it during the day, midweek when there is no one about as I don't want to poison any of my neighbours, and also my compressors sound like concord taking off and don't want an asbo.

I'd like to poison some of my neighbours!!!

There are carbon panel filters out there, not sure how long they last. Probably depend on the amount of prefiltering you do and the frequency of use. I suspect they are pretty expensive especially if you have to replace them frequently.

 

[Daz1968]

Carbon filters are common in the plant growing industry, not sure if those are suitable to remove solvent from fumes, I was hoping so.
I was always led to believe that it is only the paint mist itself that is dangerous and once the spray room has cleared it is safe to enter,
I have in the past put a paper filter in front of a fan that's drawing air out of the garage,
On my next project I am going to build a booth out of timber frame and plastic sheeting and filter air in and out of the booth I was also planning on putting a carbon filter panel on the outlet side to remove smell.
My neighbours are not close though it's mainly to reduce any chance of overspray being blown anywhere.
I also only use a touch up spray gun, devilbiss sri pro. I have managed a full respray of a classic mini with it and other than having to fill it more regular had no issues and this gives much less overspray than a larger gun as well as using less air so my airfed mask can be used.

 

[the snooper]

most home made booths will fall massively short on air flow
see below from the binks web site

To calculate the amount of exhaust air needed for the booth, a simple calculation is used.
CFM = Booth Face Area in square feet multiplied by the required flow (typically 100 FPM)
For example, and 8 X 10 filter bank (80 square feet) would require an exhaust of 8000 CFM (100 X 80) to achieve the required 100 FPM velocity.
To calculate the existing velocity knowing the exhaust volume the following formula is used:
Velocity = Exhaust in CFM divided by the booth filter area.
For example, a fan that exhausts 9000 CFM with a 10 X 10-filter bank would have a velocity of 90 FPM.