Model Expo Spray Booth - Annoying doubt!

[panzer360]

Hello, i recentlly bought the Model Expo Spray Booth because of the danger of spraying paints like enamels or hiroboy zero paints.

Well the spray booth just arrived today but the problem is that in the spray booth manual it says:

5. Safety instructions and warnings
-Never spray toxic or flammable painst or materials

My doubt is, i bought this exatclly for spraying the more dangerous paints like enamels or zero paints and now i can only spray acrylics on it?
Please someone thats knows or have one tell me what is this all about? Is this spray booth just for acrylic paints i´m afraid to spray some zero paint on it and the van or something explodes.

Please help me i have waiting for so long to paint my models and i´m waiting for you response to start or not.

The model is this:

[stevenoble]

Looking at it, it appears to have no extraction to the outside..??? If you use it with strong smelling paints such as Zero, I dare say the fumes will build up inside the room you are using it in. You need one with a pipe that you place through an open window and then the fumes are sucked through the filters, all the nasty stuff is caught and the odours are extracted outside via the pipe. That way no smells ever stay in the room. I got mine from Graphic Air and it has a pipe attached to properly extract the fumes. Works with Zero and all other paints with no smell and no problems at all.

[panzer360]

Hello Steve thanks for the quick reply. I bought the pipe also to attach to the spray booth and extract the air outside, the problem is that i don´t understand why they say to not spray toxic or flammable paints.??

Are they saying to not spray toxic fumes without a pipe to extract fumes outside or are they saying to no spray toxic and flammable paints to the fan because it might explode?
Because having a spray booth only for acrylics sucks, because revell acrylics dont even have smell...


By the way are you this Steve Nobel :

[stevenoble]

Hi, yes, I am the same Steve Noble who built that McLaren.. If you have the pipe to extract the fumes to the outside then you should be fine. What is the fan like on your booth..?? Is it sealed away at the back..?? Ideally it needs to be shielded so that no sparks from the motor will ignite the paint fumes. Maybe send an e-mail to the supplier and ask them if the fan is shielded or not. If it is and you use the pipe, it will be fine with the Zero paints etc..

[flyonthewall]

I think Steve is right and I would assume that it's just the manufacturer covering their backside regarding ignition of paint fumes.

[panzer360]

I emailed Model Expo about the warning in their manual saying to never spray toxic or flammable paint on the spray booth and the reply was:

"The manual states this because of the risk of combustion"

They only said this, so since english is not my main language what do you guys think they want to say:

-To not use enamel/zero paints on spray booth or might explode with the fan

or

-Just a warning saying that spraying flammable paint might generate a combustion if near fire for example.


Please dont tell me i spend money on a spray booth that only can take acrylic

[stevenoble]

I think they are just covering their back by saying that. If it's anything like my spray booth then the fan is well away from any paint fumes or vapours and by the time they get to the fan any risk of combustion is long gone. It's the actual motor that drives the fan that needs to be shielded, because some motors produce sparks whilst they are in use and you don't want sparks when there are flammable vapours around. E-mail them again and ask them specifically if the motor that drives the fan is shielded or not. If they say no I would return the booth to them as unfit for purpose and ask for a refund. No where on their website does it state that you can't use it with toxic paints. A spray booth should be able to be used for all paints and should certainly have a shielded motor because of that..

[panzer360]

Great answer Steve, i will have that in mind when i email them again. After that reply from them that wasn´t very clear i send them a direct question "Can i use enamel/lacquer or other flammable paint with this spray booth?"

If they reply to me i will let you guys know what they say.

Note: In the back of the spray booth i can see the fan and it says "Axial AC Fan"
I searched this in google and found this:
"Any build up of paint, lacquer or varnish can present an explosive condition, should a spark occur in the system. Therefore, all Tube Axial Fans used to exhaust a paint spray booth should have a spark resistant, cast or fabricated aluminum propeller. If the propeller should come loose or if a metal part should hit the propeller, it will minimize the chance of a spark being generated."

Does Axial AC Fan means that is prepared for toxic paints or doesn´t mean that necessarily

[RonCla]

I've got the same spray booth here which I've been spraying Zero paints and 1k and 2k clear coats without issue using a Tamiya Spray Work HG Wide Airbrush.

I've been using it in a well ventilated area with the vent hose out a window.

My instruction sheet just says for health reasons don't use poisonous or flammable paints.

In this Youtube video the reviewer is using a spray can of Halfords Primer which I think would be flammable.

http://www.youtube.com/watch?v=Z-F30...eature=related

[CFarias]

Originally Posted by panzer360

"Any build up of paint, lacquer or varnish can present an explosive condition, should a spark occur in the system. Therefore, all Tube Axial Fans used to exhaust a paint spray booth should have a spark resistant, cast or fabricated aluminum propeller. If the propeller should come loose or if a metal part should hit the propeller, it will minimize the chance of a spark being generated."

Does Axial AC Fan means that is prepared for toxic paints or doesn´t mean that necessarily

The "tube axial fan" refers to the type of fan on motor combination style and does not mean that it is prepared for toxic or flammable paints.

What's important is that you have the fan's motor mounted outside of the airstream. Take a look at the products from this company:

http://www.pacepaintbooths.com/pace/

I do not have one of these but I am an engineer by profession who specifies fans for hazardous airstreams. Seeing these units on their website I can say that they look to be top quality. Notice that the fan motor sits on top of the painbooths, out of the way of the airflow. This is what is meant by the fan and motor configuration being "explosion proof". As well the galvanized sheet metal construction means that the booth will be very rugged and be resistant to permanent paint adhesion, making clean-up easier.

The Model Expo booths advertise a 3 cfm exhaust rate. I'm not sure that this is correct as it seems excessively low! Ideally you want about 100 fpm of airflow through the face of the booth while the fan is on. The small Model Expo unit would only be moving 2 fpm (feet per minute, velocity). The smallest unit that Pace produces advertises a 148 cfm exhaust rate, which corresponds to 97 fpm for that unit, about where you want to be to have an effective paint booth.

Also, at 2 fpm I'm not sure that the Model Expo unit will be able to exhaust the air anyway once you connect an exhaust duct. There will probably be too much friction in the exhaust duct for the unit to overcome. Likewise there will be a corresponding loss for the Pace booth, but at 97 fpm there should be enough handle it.

Check this page out: http://modelpaint.tripod.com/booth2.htm

It is a great primer on paint booth design and should be required reading for all of us.

Finally, for those who venture into making your own booth. Computer fans can be used for exhaust as their motors generally are sealed in epoxy making them highly resistant to solvents and consequential fires, but they can lose performance very quickly as these fan types are very sensitive to built up paint on their fan blades or poor exhaust duct design. My opinion when designing a paint booth with these fans is to add 50% more cfm's worth of fans than what you calculate and the booth should be robust enough to handle the drop in performance.

Hope this helps.

[CFarias]

Originally Posted by stevenoble

If it's anything like my spray booth then the fan is well away from any paint fumes or vapours and by the time they get to the fan any risk of combustion is long gone.

Steve, from the picture you provided I'm not sure that your statement of the paint fumes and vapors being "long gone" by the time it gets to the fan is correct. The vapors should not dilute but should remain at about the same concentration as when they passed through the filter no matter how far down the exhaust duct they flow. The vapors will only lose concentration once they have reached the outside and dilute with the outside air.

Also, please everyone notice the paint build up on Steve's filter. Imagine all of that on your fan motor or blades. Steve is doing an excellent job of keeping his booth in tip-top shape by using a filter.

Filters do a great job of catching the particulates of paint, but the corrosive solvents (toluene, acetone, lacquer thinner, etc) will pass through the filter and right into the fan motor. The concentration of lacquer thinner needs to be about 1% in the airstream to make conditions favorable for ignition. For the purpose of our type of painting, this is well above the concentration we would be airbrushing at with a good paint booth, but it just makes good sense to be safe and get a motor that won't cause a risk.

[panzer360]

Hi Roncla, before i bought this spray booth that video review and some others opinions made me buy this.

But after what CFarias said just makes me want to throw it to the trash. Weak fan, not 100% convinced that is safe with flammable paint.

Maybe i will sell my kits since i can´t paint them, because i just spend 120€ on a useless spray booth and the tube and i´m not going to buy another one.

I´m still waiting for model expo to reply to my second email...

[stevenoble]

Originally Posted by CFarias

Also, please everyone notice the paint build up on Steve's filter. Imagine all of that on your fan motor or blades. Steve is doing an excellent job of keeping his booth in tip-top shape by using a filter.

I change the filter every couple of months. But I also use an air blower after every model. I take the filter outside and blow it out to remove all the dust and paint particles that it has trapped. It's amazing how much dust and debris the filter traps after the spraying of just one model. Once the filter is off you can see the fan assembly, and there is never any dust or debris on it at all. So the filters are doing a pretty good job of stopping all that dust and overspray from affecting the fan assembly. The spray booth is really the best purchase I ever made and it has made my painting sessions a real pleasure with no toxic fumes or smells in the model room anymore I can concentrate purely on my painting.

[RonCla]

Originally Posted by panzer360

Hi Roncla, before i bought this spray booth that video review and some others opinions made me buy this.

But after what CFarias said just makes me want to throw it to the trash. Weak fan, not 100% convinced that is safe with flammable paint.

Maybe i will sell my kits since i can´t paint them, because i just spend 120€ on a useless spray booth and the tube and i´m not going to buy another one.

I´m still waiting for model expo to reply to my second email...

I wouldn't describe the booth as useless. I find it removes the overspray adequately when using my airbrush which is all I require it to do.

It would be disturbing to find out it isn't safe to use with flammable paints though. There is nothing on the box it came in or a warning label on the booth to say it would be hazardous to use such paints.

[panzer360]

Originally Posted by RonCla

I wouldn't describe the booth as useless. I find it removes the overspray adequately when using my airbrush which is all I require it to do.

It would be disturbing to find out it isn't safe to use with flammable paints though. There is nothing on the box it came in or a warning label on the booth to say it would be hazardous to use such paints.

Don´t get me wrong i bet is a good spray booth for moderate use and acrylic paint. Some guys used it and are happy with it, but sucks the lack of info by model Expo about if their engine that drives the fan is shielded or not.

I have emailed them but didn´t get a reply only that "The manual states this because of the danger of combustion"
Try send them an email asking if its safe to spray flammable paint with this spray booth, they might answer to you .