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explosion concerns!

5K views 36 replies 12 participants last post by  atichargr 
#1 ·
okay I have just read a thread about paint explosions.... and the messages given are very mixed... I have attached pictures of my enclosure I plan on painting in... my plans are to have the compressor, and fans run off of a generator .. and the lights and fresh air hood off of the houses power via an extension cord(s). the only things inside the enclosure would be the lights and fans blowing out...(2 box fans) ... I plan on having the fans blowing out with filters on the inside... then if you look at the pictures the enclosure has a vent at the top on both the front door and back door... I just want some honest opions on what the chances are of this atucally going BOOM!!!!! by the way the enclosure is 12x20x8


thanks
simon
 
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#2 ·
Here is the danger. As you spray you will be creating a lot of fumes and particulate, which MAY be ignited by a spark. The box fans may create the spark, any light switch may create the spark, the compressor switch may create the spark. In all likelihood you will be fine but do you want to take the chance.

Proper spray booths contain explosion proof electrical equipment. Most people don't invest in it for home use and MOST people never have a problem.

It only takes one spark to ruin your life. You will find many people who have never had a problem but that doesn't mean you won't. Keep all the electrical switches out of the enclosure, keep the compressor on the outside with the airline only coming in, and try to find a fan with a sealed motor and you will in all likelihood be absolutely fine.

What is that thing like for static? you could set off the big one as you are spraying by brushing up against it. Might want to check that out.

Don't forget a respirator or breathing apparatus.
 
#3 ·
Incandescent lighting would be the last thing I would think you would want in the bomb, er.. I mean paint booth. Anyone who has ever held out a Bic and hit it w/a spray from a paint can knows all too well how much energy is contained in the solvents of paint.

You wonder about the chances that something bad will happen. Chances aren't what you need to know. What you do need to know (and that I can't really help with, except the obvious) is how to isolate spark and heat generating things from inside the room.

There are light fixtures and electrical outlets, etc. designed for explosive atmospheres- even flashlights designed w/explosion risks accounted for. While these things may be beyond your single-use budget, you still might use their principals in the construction and equipping of the booth.

A box fan's induction motor is probably not a bad risk factor (but do not take my word for it). But an incandescent bulb is nothing less than a freaking FUZE to ignite the fuel/air bomb that's created when you start spraying.

The saving grace to your particular set-up, is the flexible, non rigid walls/ceiling. They will hopefully blow out before a lethal amount of pressure can be built up, (I would think, but have no confirmation of this)- but the burn/heat risk is still there in spades, even if over-pressurization risks aren't.

Be safe.
 
#4 ·
speede5 said:
Here is the danger. As you spray you will be creating a lot of fumes and particulate, which MAY be ignited by a spark. The box fans may create the spark, any light switch may create the spark, the compressor switch may create the spark. In all likelihood you will be fine but do you want to take the chance.

Proper spray booths contain explosion proof electrical equipment. Most people don't invest in it for home use and MOST people never have a problem.

It only takes one spark to ruin your life. You will find many people who have never had a problem but that doesn't mean you won't. Keep all the electrical switches out of the enclosure, keep the compressor on the outside with the airline only coming in, and try to find a fan with a sealed motor and you will in all likelihood be absolutely fine.


What is that thing like for static? you could set off the big one as you are spraying by brushing up against it. Might want to check that out.

Don't forget a respirator or breathing apparatus.
Very good advice.. :thumbup:
 
#6 ·
If you're running a ventilation fan you'll never reach the levels
for combustion.
I watched a painter paint with no ventilation and get a cloud you
couldn't hardly see across the garage, but he never blew,
even with a cigarette.
If you get a cloud dense enough to ignite you're going to have
serious overspray problems anyway, so no one ever reaches that level.
Leave your fan on and you won't have any problems.
Like the thousands out there are doing everyday. :pimp:
 
#7 ·
jcclark said:
If you're running a ventilation fan you'll never reach the levels
for combustion.
I watched a painter paint with no ventilation and get a cloud you
couldn't hardly see across the garage, but he never blew,
even with a cigarette.
If you get a cloud dense enough to ignite you're going to have
serious overspray problems anyway, so no one ever reaches that level.
Leave your fan on and you won't have any problems.
Like the thousands out there are doing everyday. :pimp:
thank you for being honest
I appriciate all the advice and concerns.... but what I notice with a lot of other threads is that there are a lot of "professionals" and you have a lot of governmental requirements to follow (mainly for insurance purposes or you would not get a license for your facility) I know this since I am in the automotive industry and there is a lot we have to follow as well... I am also the kind of person who is very honest.. I will give people advice on how to do things, and even urge them on... where as alot of professionals will say "you can't do it or let someone who knows what they are doing do it sometimes just not to loose the possible customer or money... but if they try it you will find they will be coming back and letting you do things that they know they can't since you were honest and not thinking with your wallet.. I have worked at the same place for 19 years and have a huge following so I know this method works.. what I am really saying is yes there is danger in everything we do such as driving our cars crossing the street and so on... so lets help each other cross that street or drive a car safley and honestly, lets not try scare each other out of doing it . if we did that the world would come to a stand still from fear and we would eventually perish.
 
#8 ·
The box fans as mentioned are probably OK, as long as you start them before you start to spray and turn them off after all suspended paint has been removed. It is the starting and stopping of the fans that creates the spark. The motors are induction and as such do not have brushes to create sparks. The on-off switch is a different animal that most definitely creates a spark when operated. As mentioned the incandescent bulbs are the most worrysome. With incandescent bulbs their surface temperature more than likely exceeds the ignition temperature of suspended paint, so they are of concern. In industry when incandescent bulbs are used in an explosive classified area they are enclosed usually in a clear plastic bowl to prevent explosive gases or substances coming into contact with the high temperature bulb surface.

Vince
 
#10 ·
Any lighting that says explosion proof would be fine. It will have a more heavy duty cord and the bulbs will have a full case around them. your biggest concern would be with box fans. The motors are very exposed and they create a lot of spark just off the motor. They are exactly like the little racetrack cars we used to play with as kids. sparks shooting everywhere. Ahhh the good ol days when toys were still dangerous! good luck!!!
 
#11 · (Edited)
jimmytony007 said:
Any lighting that says explosion proof would be fine. It will have a more heavy duty cord and the bulbs will have a full case around them. your biggest concern would be with box fans. The motors are very exposed and they create a lot of spark just off the motor.
No they do not

jimmytony007 said:
They are exactly like the little racetrack cars we used to play with as kids. sparks shooting everywhere.
No they do not.

Read reply #8. Box fans are generally inductive motors that have no brushes (read cheap), so no sparks. The on-off switch when operated will cause a spark, not the motors.

Vince
 
#12 ·
atichargr said:
what type of affordable lighting would you suggest?
Explosion proof lighting will make your improvised paint booth far to expensive. Most paint booths have fluorescent lighting because it's operating temperature is much cooler than incandescent lighting.

Vince
 
#16 ·
302 Z28 said:
Fluorescent lighting would be OK as it is much cooler than an incandescent bulb.

Vince
302 thank you, that is what everyone needs the "truth".. if you noticed in my very first post on this thread I said how there are so many mixed messages given... and you caught the one with the box fan motors and interjected thank you ... that is what all of us learning and wanting to paint our own cars need ... the truth ... thank you for doing that! :thumbup: :thumbup:

simon
 
#17 ·
One other thing that is possibly worth mentioning on the fans (or most any electrical device), is that when there's a failure- like a short circuit because of old or faulty wiring, for instance- that sparks (thus an ignition source) can be created. So while an induction motor is a safe motor, spark-wise, it can still be an ignition point.

The best bet here, IMO, will be to use a new fan (or any electrical component- extension cords, switches, lights, whatever) that has an hour or two of run time on it, previous to be used in the "booth". This might be seen as overly cautious, I don't know. But I wouldn't trust brand new (as in, the first use of a component in the explosive atmosphere) OR too old, either one.

Static can be lessened by painting on a day that isn't cool and dry, and wear cotton clothing/overalls. Probably best to avoid plastic sheeting, for instance.
 
#19 ·
302 Z28 said:
The box fans as mentioned are probably OK, as long as you start them before you start to spray and turn them off after all suspended paint has been removed. It is the starting and stopping of the fans that creates the spark. The motors are induction and as such do not have brushes to create sparks. The on-off switch is a different animal that most definitely creates a spark when operated. As mentioned the incandescent bulbs are the most worrysome. With incandescent bulbs their surface temperature more than likely exceeds the ignition temperature of suspended paint, so they are of concern. In industry when incandescent bulbs are used in an explosive classified area they are enclosed usually in a clear plastic bowl to prevent explosive gases or substances coming into contact with the high temperature bulb surface.

Vince
I painted a truck in a booth with incadesent bulbs....when in the bed I stood up hit one with my big head and cut myself,then it glowed real bright and arced out ....at the very least I could have electrocuted myself....they made it very hot too.....bad idea...
 
#20 · (Edited)
As stated in a couple posts above, the chance of creating an explosive atmosphere in your setup is extremely remote. Takes a threshold air/fuel ratio to get there and it would be hard to do w/o vent fan, let alone with one. I would worry more about being hit by a falling airplane, swallowed by the earth opening up in an earth quake, etc.

My (hobby) stick framed and drywalled booth has seen many, many paint jobs going thru and not a whimper. I use the squirrel cage blower from an old 5000cfm swamp cooler blowing out w/ 1/2hp induction motor directly in the air flow. This setup changes the air in the room every minute or so. I never even come close to generating a cloud. Of course I use a spray mask but I'd bet if you didn't stand between the fan and my spray gun, you would probably be challenged to smell the paint!

I did a search on Yahoo for "Paint Booth Explosion" and found zero incidents, and that's a pretty good endorsement since gory web pictures are a staple when they exist. I did take some precautions such as embedding 14 4' fluorescent fixtures in the walls and ceiling and covering each with a clear poly sheet but that is more to protect the lights form me running into them and breaking them and from me spray painting them. Another reason for going florescence is the light color. The whiter the light the truer the color you see in your booth. Lighting is rated according to its Correlated Color Temperature (CCT) is a measure of the "shade" (electromagnetic wave length)of whiteness of a light source. It is listed in the units of degrees Kelvin or the equivalent light wave length given off by by a 'blackbody' (hypothetical perfect radiation emitter) glowing at that temperature. Incandescent lighting is rated at 2700K which is yellowish-white and isn't the best in an environment like a paint booth where you are trying to carefully adjust the color that will be seen in a daylight setting. Halogen lighting is 3000K which is an improvement. Fluorescent lamps are manufactured to a chosen CCT by altering the mixture of phosphors inside the tube. Warm-white fluorescents have CCT of 2700K and are popular for residential lighting. Neutral-white fluorescents have a CCT of 3000K or 3500K. Cool-white fluorescents have a CCT of 4100K and are popular for office lighting. The latter two are better for a paint booth compared to incandescent lighting. Daylight fluorescents have a CCT of 5000K to 6500K, which is bluish-white and are the best possible lighting for a paint booth. They really suck for lighting a home though. That's why the make the 2700K warm light versions. Plain vanilla 4100K cool-white bulbs are great but I sprung for the 5000K Daylight ones in my booth. Don't know if I can really tell a difference but what the hey!! Either are tons better than regular incandescent light bulbs were.

IF your setup ever did pop, you would launch that tarp cover to the stratosphere and be running in circles saying 'Where's my mama?' for a few moments but shouldn't suffer any real bodily harm.

To make a short story long, yes there is a potential for an explosive mixture of paint fumes and air, no doubt about it. However the simplest precautions completely avoid that possibility and your setup far exceeds that requirement. "Paint on Garth!!"
 
#22 ·
I appriciate everyones input... and I am glad we were able to somewhat debunk some of these myths... and now I think my fiance will be a little more at ease about me painting this car... I myself was not as worried since I have worked in the automotive industry for years and even been stupid enough to pull gas tanks with a cig in my mouth.. and thanks to Mike for making me do all this home work LOL thanks master :thumbup:

simon
 
#23 · (Edited)
One day we heard a really big boom .

The workers at a local Macco Auto Paint shop 8 blocks up the street were cleaning the paint booth fan blades and flue with lacquer thinner for some odd reason.. One of the workers lite up a cigarette.

It was his last smoke.

There was a little bit of fire to go with it..

It killed him instantly dead as a mackerel ...

The shop closed and never reopened..

Safety first, safety is no accident...

Had a fan been blowing it probably wouldn't have happened..

http://www.google.com/search?hl=en&...ntain+View+Maaco+Shop+explosion+death&spell=1
 
#25 ·
Never said it is impossible to create a bomb! Happens all the time in the grain industry - grain dust, mixed w/ the right amount of air + a piece of bailing wire rattling and sparking down pneumatic duct = BOOM!! Lacquer thinner, gasoline, rattle can paints, finger nail polish remover, wood sanding dust, etc., etc. etc., in the right mixture with air and a spark will blow every time. Point is, with a ventilated booth, solvent concentrations will be several orders of magnitude too low to be an explosion risk. Analogy in the woodworking industry is central dust collection systems (I have one of those too in my shop!). Wood dust in air is every bit as explosive as paint solvent. However the woodworking industry uses dust collection systems all the time because again, the system is moving so much air that the dust concentration is rarely (won't say never cause it DOES happen) high enough to cause a hazard.

By all means if you are not confident in what you are doing, go with the explosion proof components. However the risk (NEVER zero in anything we do in life) is way less than being struck by lightening, hit by a falling jet liner, going thru a year w/o a tax increase from some branch of government.
 
#26 · (Edited)
I used a car cover with clear visqueen on the sides to allow natural light in. This avoided the issue of lighting.
I also used box fans outside the enclosure blowing air inside the booth through filters. Air compressors were outside and away from the booth.
I also grounded the car inside the booth with a chain.

Pictures here if interested:
http://chris66dad.tripod.com/id24.html
Ron
 
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