Idea for makeshift spray booth.

[Joe Hillmann]

I started doing quite a bit of engraving work that I color fill with spray paint. In the summer I had an old table in the back yard and would do the painting out there so I didn't have to deal with the fumes. Now that it is getting cold out I can't do the painting outside so I rigged up a makeshift booth and figured it was worth sharing.

All I did was take the larges cardboard box I had and cut a 5 inch round hole in the back. When I need to use the spray booth I disconnect an exhaust pipe from one of my lasers and put it into the hole in the box. Then I can spray the items inside the box and exhaust system takes the fumes away. After I am done spraying I leave the item in the box with the exhaust on for a few minutes and no fumes get back into the work area.

I actually plan to build a wooden spray booth and run a dedicated exhaust line to it but for now my makeshift set up does the job.

[Scott Shepherd]

Joe, careful with that. Some fumes are bad for that, and can end up igniting and causing an explosion. Do some research before you get too far into it to make sure you aren't setting yourself up for a really bad thing to happen.

[Rodne Gold]

Reminds me of an incident I had , we used a Karcher wet and dry vac cleaner to suck up residue on our CnC router , we used a sacrificial table and double sided tape to secure the material. After all the cutting/engraving we then used benziene to loosen the tape we used to hold stuff down with It was never an issue with the Karcher , used to suck it all up no problem..till one day BOOOM..... the thing blew up!!! No one was hurt and no fire , TG...
We stopped using benziene a long long time ago when we found it was carcinogenic and we started using safety solvent..

[Kev Williams]

concur with the others-- you'll soon end up with blower that won't blow because crud will stick to the paint on the blower blades, then more paint will stick to the crud, then more crud, etc...

Consider getting yourself an extractor fan designed for paint. My 'booth' is my basement stairwell, I've had a paint fan sitting in the same place for years- It's fairly covered up so the pics aren't the best. The fan is belt driven by a motor mounted on top, which can be isolated from the paint and fumes. This one is pretty large, I believe our neigbbor (a car painter) gave it to my dad many years ago, there may be smaller ones available...

[Rich Harman]

On both of my blowers the motor is isolated from the airflow. Definitely a concern for shop vacs though.

[Ross Moshinsky]

They make filter media for this specific application.

[Richard Rumancik]

I think Joe's idea is quite workable. Certainly it is not suitable for use with shop vacs and in-line fans and such, but most laser exhaust systems will have a motor that is not in the airstream of the exhaust air. I made a similar paint booth a few years ago. What I did was install a furnace filter at the back of the box and then the air is exhausted from behind the filter. You can get furnace filters with various degrees of filtering and in various sizes. They are not very expensive and could be doubled up if needed. The larger wet particles will adhere to the filter media and the gases will be exhausted.

I think people have to keep things in perspective here. We should all work safely and prudently but Joe is not using his paint booth to paint large metal parts. The amount of spray paint that is typically used in color filling in a year in the average shop is usually not very significant. If someone has an industrial operation with very high production, then of course more appropriate equipment should be considered.

I think the forum should encourage new ideas and suggestions, and perhaps try to improve on the suggestion or idea. If someone suggests something that is dangerous then certainly a warning may be in order, but often responses tend to concentrate on what could go wrong as opposed to encouraging innovation that may be useful to other members. It is more obvious when you read a whole thread at once.

Joe, I suggest that you add lighting to the box as well and consider a rotating table so that you can spin the work. And yes, make sure that your lighting is shielded so that it won't cause an explosion.

[Jerome Stanek]

For light you may want to try leds

[Chuck Stone]

With all due respect, Richard .. that's kinda like saying "Go ahead! There's only ONE bullet in the revolver...."
A safety issue like explosive fumes is dangerous, and it isn't dangerous only for large operations.
I'd MUCH rather see the warnings than try to pass it off as something that we don't need to worry
about.
You mention that there isn't a lot of paint going through, and using filters to keep it out of the motor.
(if I understood correctly) but the paint isn't the problem. It's the fumes. There's a reason that shops
pay extra bucks for explosion proof motors.. it isn't just hype.

[Richard Rumancik]

I don't think I implied that one should ignore safety issues.

Each member obviously needs to evaluate a suggestion based on their own circumstances. If you are really doing a lot of painting, then perhaps this is not the solution for your application. And if you have a motor that is in the same environment as the paint fumes (such as an in-line blower) then it would not be advisable. However, with a typical blower/motor there should be no exhaust gasses in the vicinity of the motor itself. If there is then there are leaks in the exhaust system.

This is my analysis of my particular situation. My exhaust system is exhausting 300 cfm and if I add a small fraction of a cfm of explosive gases to the flow, the concentration at the exhaust end would be an extremely small percentage. If I had a leak of a few percent from an exhaust duct after the blower (and I doubt I do) the concentration of volatile gasses in the vicinity of the motor would a fraction of a small fraction. The only part of the duct that leakage is an issue is the section after the blower which in my case is 2 feet of straight metal duct. The section before the blower is under negative pressure and will not spill volatile gasses even if there is a hole. Everyone needs to decide on the appropriateness for their own hardware and work safely.

You say that the paint isn't the problem . . . we agree on this. I was responding to Ken's concern.


concur with the others-- you'll soon end up with blower that won't blow because crud will stick to the paint on the blower blades, then more paint will stick to the crud, then more crud, etc......

The filter was not intended to keep the paint out of the motor, as exhaust should NOT be going through the motor. As I said before this idea is not suitable for in-line blowers that have the motor in the airstream.

The filter is to keep paint out of the flexible ducting and perhaps keep it out of the blades of the fan. (Although I am somewhat skeptical that the paint would be wet enough to stick to the blades in my case where I have 30 feet of duct.)

Everything has risks but if we just concentrate on risks and never on innovation the forum tends to discourage any new ideas. How about a response such as "Great idea, Joe. Don't forget to consider x and y to ensure safety."

[Scott Shepherd]

Everything has risks but if we just concentrate on risks and never on innovation the forum tends to discourage any new ideas. How about a response such as "Great idea, Joe. Don't forget to consider x and y to ensure safety."

On a public forum that's worldwide, it would be very foolish to post ideas that could end up getting someone killed, their house set on fire, or anything that would damage or harm someone. Not everyone reads every single post on a thread. If ideas like that aren't put into check, then someone might read the first post and go off to make one, doing everything wrong and killing someone in the process. Paint fumes, motors, and lights are a SUPER DANGEROUS and DEADLY combination. There's a reason they make explosion proof motors for fans and explosion proof lights for lighting.

To allow people to say "Great idea" on something that could kill them, I think is irresponsible. If you want to encourage them, then say "That's wrong, you risk killing yourself or someone else by doing that", and then offer up the safe alternative. I haven't seen the safe alternative mentioned, rather just more adding on of things that are equally as dangerous, with suggestions that it's okay to do.

There are WAY to many stories that can be found online of people getting seriously hurt or killed by doing the things that are being suggested by some. How that's "killing innovation and creativity" is beyond me. You have to be alive to be creative.

[Bill Cunningham]

If you use a shop vac on 'blow' into a venturi with the flow going out a window there will be no fumes in the blower, the box, or the building.

[Scott Woodson]

Have you thought about switching to a water based paint? I have a small enclosed shop and took a while to get used to, but once I got the process down it looks very nice...and no explosion!

[Dave Sheldrake]

Each member obviously needs to evaluate a suggestion based on their own circumstances.

Problem is Rich sometimes readers can confuse desire with ability. There may be readers who make something very similar (based on their own belief it is safe) when in reality their version could be a potential bomb.


he concentration at the exhaust end would be an extremely small percentage

Small concentrations are usually more dangerous than saturations when it comes to explosive gasses and materials. For example Xylene has a lower limit of 0.7% when you get a boom and yet at 6% the atmosphere (fumes mixed with air) is no longer a real risk as their isn't enough Oxygen / Fuel to ignite. The vapour equivalence is what matters, a gallon of Diesel fuel in an open top drum in a room 20 x 20 x 10 feet isn't going to be a problem if a match is dropped in the drum. The same gallon as a vapour spread round the room is going to create a pretty big bang. The difference between Extinguish, Burn, Deflagrate and Detonate are fractions of a percentage in many cases.

cheers

Dave

[Martin James]

bill do you have a pict of said setup?? thanks

[Bill Cunningham]

bill do you have a pict of said setup?? thanks

These are the simplest ones
http://www.myonlinediary.com/wall-insulation/images/201-vacuuum-cleaner-blower-nozzle.JPG
http://www.myonlinediary.com/wall-insulation/images/detail-of-inside-venturi-blower.jpg
Looking at the one above, the air source blows through the left side and out the right side. The pressure is decreased in the lower tube by the air flowing across it. this would be fed by a hose to the paint cabinet, and the resulting vacuum would suck the fumes up and they would flow out with the air stream flowing from left to right and the right side would feed out the window or whatever.

[Chuck Stone]

the venturi makes a lot more sense from a safety point of view..
Very nice