Safe Spraying on Site

      Here's a discussion about how to prevent overspray from setting off alarms or explosions when finishing on site in a high-rise building. July 18, 2013

Question
I refinish a number of commercial office towers (lacquer and CV). Often there are sensors that I can't reach to mask off (elevator shafts, ultra high ceilings). Alarms are driving me crazy and making me famous!

So help me with my decision. I'm looking at the Iwata w400lv compressor driven, Appolo 7500t turbine, AAA cat or Kremlin. I like to use gravity feeds for the ease of c hanging products and cleaning CV. I really like the idea of the turbine, low overspray gravity, plus portability. I have consistently read that the 3-M 10 gun is the top rated turbine gun. Whereas the Apollo can be both gravity and pressure pot. So can anyone compare the 3-M 10 gun with the Apollo 7500t turbine gun for quality of finish?

More information: The Iwata is LVLP. I know turbines are slow but I will gladly trade speed for low overspray!

Forum Responses
(Finishing Forum)
From contributor F:
I will vote for the Apollo 7500. I have 2 of them using a 3 stage turbine. There is minimal overspray, but nothing compared to conventional guns using compressors or airless/air assisted airless units. The finish quality of the Apollo is excellent.



From contributor P:
AAA systems produce less overspray than a turbine, but they need a compressor and you have to flush the lines out to clean or change materials. The most portable AAA unit I've seen is the one CAT sells that has a small compressor and the pump mounted on a cart.

I have a CAT (not the model with the compressor, but same pump) and also an old workhorse Turbinaire HVLP. If you're spraying for hours at a time, the AAA is the way to go. Much faster, the gun is way lighter and can be sprayed at any angle.

If you end up going the turbine route, variable speed unit can theoretically help keep overspray down. I say theoretically because thicker finishes require that the air pressure be pretty high to get good atomization.

What kind of finishes are you spraying?



From the original questioner:
I'm spraying solvent CV and pre- or post-cat lacquer. I will be using the same in waterbased when the job demands it.


From contributor A:
You're lucky the firefighters call you famous and don't kick your butt.


From contributor P:
Sounds dangerous. What are you doing for ventilation?


From contributor A:
You realize that overspray explodes and burns like napalm? If you're a smoker, take your smoke break outside of the building. For heaven's sake, be careful.


From the original questioner:
If you're lucky enough to have a door that opens you can seal it off (plastic) and use power exhaust hoses (12") to help with exhaust. Oddly enough, for all the hvac alarms, I've never seen a fireman. I really believe if I can vastly reduce the overspray, I will be successful. With these big hvac systems you can't just prop the doors open, as the sensors will pick up the temp differences and alarm. Thus plastic the door and seal up the exhaust hose slit.

Never smoked anything but hot dogs, but I appreciate the wisdom of your concern!



From contributor M:
I have never heard of overspray being like napalm. The man that taught me to spray over 30 years ago did so with nitro lacquer, with a lit cigar in his mouth.


From contributor O:
I also knew a man once, a hardwood floor finisher with over 30 years experience, who died a very painful death after finishing a floor with lacquer. This was quite common if a customer needed a refinish done quicker than a varnish could accomplish. The man wasn't smoking, but the water heater pilot caused a flash over, severely burning the man. I saw the man (who I knew well) on the 6 o'clock news that PM, standing with the EMTs outside the home after the explosion, with skin literally hanging from his body, quite coherently telling them he's done this many times before and never had a problem. He died about 3 days later.


From contributor R:
Take your safety seriously. The overspray can and will travel to the source of ignition if nearby, and then you're going to have a really bad day.


From contributor V:
While a youth, I worked for SoCalGas. I worked on the emergency crew under the tutelage of a crusty old-timer who smoked while working on gas leaks. He claimed (correctly) that the ignition temperature of natural gas is above the temperature of a lighted cigarette, so it was safe. He was right, but...

So the cigar story is plausible, but so is the ignition of atomized solvent finishes. Be careful of dogma, experts.



From contributor A:
If you start a fire in a high rise building, all of this hair-splitting won't matter one bit.


From contributor M:
Anyone that sprays any solvent based material without adequate ventilation is a fool. I sure would not want to stand in a room full of overspray.


From contributor R:
Contributor A hit it on the head.


From contributor E:
I notice less overspray when using a small airless (Graco 190) than the HVLP gravity feed.


From contributor G:
Explosions from solvent vapor are like explosions from any other flammable vapor - it requires the right mix of gas and oxygen. You never really know if you are near the critical mixture until it is too late. So yes, people do get away with it for years, and some don't get away with it for very long at all.

Mythbusters has done some testing on flammable vapor explosions and their tests confirmed the fact that a particular mix of gas and air equal a very vigorous explosion. I follow the rule that a man should never gamble more than he can stand to lose.



From contributor E:
To the questioner: I would love to know what you pay for liability insurance. Most insurers look at the worst possible situation. If you don't mind I'd also be thrilled to know your liability limits. I think mine is outrageous, and I don't spray anything on site, much less in a high rise.


From the original questioner:
Thank you all for all your responses. So waterbased is the way to go! I have enjoyed reading this forum for years and I have great respect for this. I am still weighing the decision of lowest over spray (with water base). To that question, I have read 3 different answers. Maybe there there is no clear consensus?


From contributor G:
I think the cat H2O system would be your best bet. I have a Kremlin system and no experience with the CAT system, but AAA is the way to go and it seems CAT is more affordable in initial purchase price and parts. When I started using my AAA system, I turned down the exhaust fan in my booth because the low overspray did not require as large a volume of exhaust air. I would get in contact with the CAT rep and have them demo a system for you.

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