What are the chances of having an explosion if non water based spraying is carried out in a non ventalated garage???
You may think this a stupid question….but I reckon that there are a lot of people out there who spray without the relivant safety equipment in place.
To date I only finish by hand application….but I would like to know if anyone has experienced what happens when the vapours come into contact with the electrical lighting system??????
Are they alive to tell us????
Well I've done it myself. But my garage is unheated so I'm usually doing it in the warmer months with the garage door open and a roof/cupolo exhaust fan running (more for keeping the temperature comfy than worrying about exhausting fumes). I've got a breakdown spray booth I screw together made out of 1x2 frames covered with clear plastic sheeting otherwise I'd have to keep the garage door shut to keep the crud out of the finish. I've had electric lights on full blast to see what I'm doing - even 500W Quartz Halogen tripod mounted spots. I'm probably just an accident waiting to happen.
I've never experienced and explosion but I can tell you what happens when you hold a match in front of a can of hairspray and push the button.... Nuff said ? Given the right conditions anything is possible. You could always challenge the "Myth Busters" with the question, they like blowing things up.
The Tool Guy
I think Chippendale used to spray his now practically priceless antiques in a shop that had no spray booth.
Get the humour?
Put on a nice hand applied finish and be proud of it.
If you're building production pieces then move your operation to an adequate commercial facility.
Got it!!!! He was the poor guy that never got paid and died with nothing!!!!! Bloody Royal Family!!!!
Are tools higher in price now that the $ is at the rate it is?
Are you seeing any price increases in imported, goods, wood etc?
or are things much the same?
No, he actually was quite financially successful.
StrongBO, what is it you hope to gain from spraying finishes? Practically every finish in current use was originally applied by hand quite successfully - lacquer, shellac, varnishes, paint.
Are you running production out of your residential garage workshop?
I would think that the vapors would build quite quickly in a garage-sized space with no windows or doors open. If you swing open the doors and windows you will eliminate the vapors, but you will have an environment not optimal for spraying finishes - especially lacquer and shellac.
Edited 11/25/2004 8:05 am ET by cstan
I have heard that natural gas needs a ratio of 95% air/5% Nat gas to be a hazard, but you need a spark for this to explode. If the lights are already on and the fan doesn't produce sparks, it's not going to explode, but the health concerns are still there.
"I cut this piece four times and it's still too short."
FYO Natural gas combusts at 4% to 14% gas to air .Above 14% it is stable but you suffocate.
Sorry to contradict you but his workshop caught fire and all his precious tools were lost. From then on his business fell into financial ruin and he died penniless.( now I am going to break down sobbing!!!!)
Like many other home wood workers, some where along the line, when you have been at it for a while, you start to look at other possibilities. Finishing by spraying was just one of those avenues for me. After many discussions I am sticking to hand finishing. But no doubt it will raise it's head again when something new comes onto the market.
Good speaking with you, and have a happy Thanksgiving!
So, he was a financial success until his shop burned down. Wow, what a total loser.
Edited 12/2/2004 8:52 am ET by cstan
I could be wrong, but I think you're confusing him with Hepplethwate...Mike Wallace
Stay safe....Have fun
Solvents are hevier than air. thats one reason why our wall recepticles are around 4' of the floor. My home garage is high up as well. The electrician said it was code. Extension coards, drop lights, evan electric hand tools are a serious potential risk.ALL are tools were air for a reason. Our insurance company was fussy but we reduced our rates buy following their suggestions.
I'm no chemist, but I have sprayed a lot of shellac ( I believe the alcohol thinner is one of the most explosive) in the the typical garage/shop conditions. Halogen lights, garage door part way open exaust fan running. The running joke between my helper and I is how long do we wait before we light a cigarette. I suspect that before the vapors reach the consentrations needed to explode due to a switch being thrown or a lighter being flicked you would feel nausious, even with a resperator. You definately need cross ventalation and the like.
Where are your furnace and water heater - and are they gas units? Mine are in the garage (i.e. shop) and I wouldn't dream of doing any serious spraying in there. With my luck one or both would fire up and I might find myself in the next town - lol.
There is little chance of an explosion unless you have a flame source in the garage such as a water heater. An explosive mixture needs to be by volume in air at least 2.1% (Propane), 1% (Gasoline constituents), 1.8% (MEK), and the most dangerous is Turpentine (0.8%). These are all in the 10,000 ppm range, and you'ld probably be passed out at those concentrations, unless you're standing in the door spraying towards the water heater. Even if you do hit the magic concentration #, the explosion won't propagate unless you are well above those lower #s.
Assuming your garage is 20' x20' x 8' high, with propane you'ld have to put about 130 grams into the air to get a weak explosive mixtere, or nearly 1/2 of a benzomatic cylinder.
After thinking about the above, I think that if you work at it, you CAN blow yourself up. The easiest way would be a closed garage (sized as above), an ignition source, and spraying about a quart or more of lacquer in a short period of time. I think you would need a respirator to survive long enough for the explosion to take place, but it can be done.
Please do not take chances! We are all tempted and we joke about it if all goes well. We recently had a family of seven children and a mother die in a fire. That is no joking matter.
If someone is stupid enough to jeopardize their family or theirself, they should immediately go jump off a cliff and do everyone a favor and put no one else in jeopardy. At least their insignificant self can become useful fertilizer at the bottom of the cliff.
Nothing, gasoline, acetone, or alcohol is dangerous if the proper ventilation and safey precaution is used. If you do not have the proper ventilation then you are a foolish idiot to use it.
A good friend of mine got pretty badly scortched by a propane explosion in a trailer.The flame front passed quickly and did not ignite the trailer, blew him out the door but still burned his face and eyes.
So I guess my saying that 5% natural gas to 95% air ratio being explosive is correct, although on the low end. Sorry to hear about your friend.
"I cut this piece four times and it's still too short."
Spraying any kind of flammable finishing material (especially lacquer) is fraught with risk.
Years ago when I first got into spraying, I brought around an acquaintance of my mine who is an expert in all this.
From what I learned then, and since, I would say an explosion (while you are actually spraying) is unlikely -- unless you have a very rare, but still possible confluence of events. The real problem with spraying lacquer is the build-up of residue over time (the dust that seems to fly everywhere, even with a HVLP system). This dust is highly flammable, and once it accumulates in sufficient quantity, and the right kind of ignition source is present, you'll get a quick and disastrous fire.
His advice was don't tempt the fates, and spray only in good weather when you can properly vent the vapors to the outside.
BTW, he suggested that a respirator was not sufficient for your personal safety -- he recommended eye protection as well. I wear a pair of wrap-around safety glasses.
The eyewear is especially important if you are spraying into a cabinet. The blowback comes right at you and goes right where you don't want it. If it can continue past whatever you're spraying, it's less of an issue, but should still be considered.
"I cut this piece four times and it's still too short."
Your concerns are real , and they say accidents happen when we least expect them . The way I see it one of the largest dangers would be a light bulb , florescent or incandescent either blowing or breaking or exploding . Often times the fumes and vapors linger up high in the room if a conventional spray rig is used , with an airless since no air is mixed with the material the fumes seem to stay a bit lower . Never the less in an approved type of spray booth area , explosion proof lighting is required. The spark or flash is contained within the glass cartridge or enclosure , to prevent contact with the air or fumes in the area .Not that we all use those types of lighting fixtures , but we should . If you use a fan to help blow the fumes out a window or door , you can get excellent spraying results even in a small area as a garage . Larger pieces or jobs may not be practical without an adequate exhaust system and temperature control for the winter months.
good luck dusty
It sorta comes down to "it depends" or "poo-poo happens(is that a nice way to say it??)
I have worked with a guy that would spray a whole house full of cabinets in his shop with the doors closed. If you looked from one end of the shop to the other, it was like lookin through a fog bank. He would stand at the door entrace and smoke a cigarette while waiting for the lacquer to dry. No kaboom!!
About 3-4 years ago, there was a buiding in Westwood, Calif where the finisher was spraying solvent lacquer in a hallway for a homeowner. I think it was the 17th floor. It must have been pretty thick because when a halogen work light fell and exploded, it knoched drywall off the wall on the 26th floor. Some people were hurt too. These were not cheap units either.
I've been on too many jobs over the last 20 years that sounded just like the last one and nothing has happened.
This why I have planned to build a seperate enclosure for my propane water heater. Keep it away from all the flamable stuff in my shop.
THE REAL FACTS OF EXPLOSIONS !!!!!!!!!!!!!!!!!!!!!!!!!
I have worked for a gas utility co. for 13 years and I am a wood worker as well. I have read all of the comments above and we all need to realize the potential and real hazards of explosions. The letters above are only a small part of the possibilities. What we need to realize is that the possibilities are endless for explosions. I say that from many years of research and enough explosions and a few deaths. What it really comes down to is this. if you think it can explode it proably can. in short if you dont play on the train tracks you cant get hit by a train. Dont put you or others in danger of an explosion.
The explosive range of natural gas is between 5% - 15 %. I have investigated all of them. A 5% explosion will blow out all of the windows in the house and possibly some doors, a small chance of death and usually severe burns. and a big woof is usually heard. A 10% explosion is a loud boom, loss of windows, doors, walls, severe burns, followed by fire and small chance of survival. A 15% explosion is a severe bang, COMPLETE LOSS of structure, a fire is guranteed, and no chance of survival.
I can tell you I have seen all types of these explosions, A 5% will melt all of your clothes to your body, and a 15% will level your home. There have been many many different sources of ignition in all of them, and you also need to understand you will never ever be able to tell what the explosive level is of your area.
A side note also of carbon monoxide when you spray in your basement. My job also includes investigating carbon monoxide calls, and I can tell you that saw dust and spraying in your basement are very dangerous to your house heater. Spray and sawdust get up inside of your heat exchange and cause the house heater to make very high levels of Co. (more than 400 ppm) inside the flue pipe. Get your house heat inspected every year and have it tested for co. Think about it, one of the most preventable deaths is co. poisoning. Get a couple of co. detectors for the house, not just 1.
Edited 11/27/2004 11:50 am ET by cass
There was a tragic explosion and fire in a triple-decker house in my neighborhood just a couple months ago. The floors were being refinished in the vacant third-floor unit, and the floor finishers kept the windows closed to keep the dust off the drying spray lacquer (this was apparently standard practice). Vapor built up in a stairwell and, well, boom. One worker was killed instantly and another died a day later from third-degree burns over basically 100% of his body. The third floor was completely destroyed by fire and the other two units had massive smoke and water damage (fortunately, nobody else was home at the time). The house was demolished two days later; it's now a hole in the ground.
the short answer is ... BANG
the classic industrial/commercial small scale explosion (small, as in not big enough to demolish the whole building) is when solvent vapours come into contact with an ignition source. A common event is when the vapour from a solvent based floor cleaner comes into contact a gas pilot light.
this thread has lots of comment about explosive concentrations. However, for an explosion to occur you don't need the whole room to reach the explosive concentation, just a layer or pocket of air at the right concentration and an ignition source.
However, apart from the potential to go bang, you also have to think about your respiratory health. I don't know about you, but I don't like wearing a respirator any longer than I have to. If I were into sprayed finishes, I'd build a ventilated booth (exhausting to the outside) just so I could take the respirator off as soon as I finished spraying, rather than hours later after the vapours had disipated.
It seems to me that there maybe a little too much panic here. I agree, don't spray in a shop with all doors closed and no ventilation. But, I don't see a problem with spraying in a shop that uses adequate ventilation and isolates the actual risk. Here is what I do. I have built a spray area by attaching poly sheeting from the ceiling in front of my garage door to create a 10x10 spray area that is open on the back side. I place exhaust fans in front of the garage door and seal around the door. I open the windows nearest my heater (a hanging gas heater), which is opposite the area of the shop that to make up warm air in the winter. So the heater blows towards the spray booth opening and the exhaust fans suck out. With this set up, if I stand at the opening of my booth and spray I can actually see the spray pattern head right through the fans.
Everyone has there own level of comfort and the key is to control the spray and get it out as quickly as possible and remove all ignition source in the area that you are spraying. You should use an explosion proof fan for exhausting.
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