spray booth design brain pickin'

[atotalnincompoop]

i have decided to build an open faced, colapsable spray booth. perhaps 5-6 feet wide, running from floor to ceiling.
i am going to need a fan to draw the fumes outside through some air filter, the kind traditional booths use.
how would i determine the size of fan needed and because the booth is an open design, would i need an explosion proof fan?
keep in mind that i am trying to build this thing for next to nothing, just to make this a little harder for you guys
this picture is just for reference, my intention is to build something along these lines.

 

[creativecars]

i have decided to build an open faced, colapsable spray booth. perhaps 5-6 feet wide, running from floor to ceiling.
i am going to need a fan to draw the fumes outside through some air filter, the kind traditional booths use.
how would i determine the size of fan needed and because the booth is an open design, would i need an explosion proof fan?
keep in mind that i am trying to build this thing for next to nothing, just to make this a little harder for you guys
this picture is just for reference, my intention is to build something along these lines.

I have had similar thoughts for several years.
First, what are your needs?
What projects are you wanting to spray? What materials are you going to spray?
The explosion proof fan is going to be the most expensive. $ 800.00 new
Take a look at Autobody Toolmart on line. You can compare sizes and CFM of air movement.
I am looking at a homemade modified down draft for my shop and think that is a better design over a cross draft. I have used both professionally and even at home I think I can get it done for less than 1000.00.
Good luck.

 

[Kevin54]

If you want to vent it outside, look into a furnace blower hooked to a ductwork with a filter in the duct. The only thing is that you may need to close down the opening somewhat to equalize the incoming air to the outgoing air.

When I painted my truck in my garage, I had a furnace blower mounted in 2' tall plywood panels that went under the garage door. I then sealed off the top of the garage door. I opened the window at the other end of the garage and had a filter in it. Worked great.

 

[CARS]

For what its worth:

The term "Explosion Proof Exhaust Fans" must be quantified as to its true definition. There is no such thing as "Explosion Proof" either in exhaust fans, blowers or motors. Fans can be manufactured to be "Spark and/or Explosion Resistant". The Air Movement and Conditioning Association (AMCA) has three classifications for "spark resistant" fans and blowers. These are defined as AMCA Types A, B or C spark resistant construction. Type A construction requires that all materials of the fan or blower that are "in contact with the air stream" be made of spark resistant nonferrous material such as aluminum or brass. Type B construction requires a nonferrous wheel and a rubbing ring around the hole where the fan or motor shaft enters the fan or blower housing. Type C construction requires a nonferrous plate on both sides of the inside of the fan or blower housing. The type of construction you require is dependant on the ambient location and/or application severity your fan will be subjected to. You need to be very careful in selecting which type of spark resistant construction you require and specify. If you are not knowledgeable in this area, you should hire a consultant that is.

Explosion Proof motors are not guaranteed to be explosion proof either. They are designed so "if there is an explosion within the motor, the motor design will contain the explosion within the motor and not allow it to go to atmosphere". Explosion proof motors are designed or rated by Classes, Groups and "T" Codes for the atmospheres they will be operating in. If an explosion proof motor is improperly selected for the actual ambient atmosphere it is operating in, it can cause an explosion. Again, if you are not knowledgeable in specifying what type of explosion proof motor you require for your application, rely on someone that is trained in this area.

 

[atotalnincompoop]

If you want to vent it outside, look into a furnace blower hooked to a ductwork with a filter in the duct. The only thing is that you may need to close down the opening somewhat to equalize the incoming air to the outgoing air.

When I painted my truck in my garage, I had a furnace blower mounted in 2' tall plywood panels that went under the garage door. I then sealed off the top of the garage door. I opened the window at the other end of the garage and had a filter in it. Worked great.

i think i have an old squirrel cage blower motor around here somewhere, i can make a tapered transition on the other side of the wall, down to the blower intake plenum. if the blower motor is going to be mounted on the back side of my garage, i'd better make some sort of cover for it as well.
ok, now the wheels are turning

 

[tncatadjuster]

I had good luck making a temporary one using positive pressure. Used 2"X4" frame with 1" battens and visqueen. Clamped with large c-clamps to framing member. Florescent lights were used outside the envelope. Wet the floor inside the booth.

Just a few hours to assemble, with min. storage.

 

[ptschram]

If you have sufficient airflow, the concentration of flammables in the airstream will never rise high enough to be of concern.

With an open-front booth, I can't see who you could possibly have enough to cause a problem.

 

[atotalnincompoop]

If you have sufficient airflow, the concentration of flammables in the airstream will never rise high enough to be of concern.

With an open-front booth, I can't see who you could possibly have enough to cause a problem.

this is what i was thinking.

 

[MP&C]

First, what are your needs?
What projects are you wanting to spray? What materials are you going to spray?

Before you decide on anything, I think these above questions need to be answered so you can safely design a system around that..

The biggest disadvantage of the positive pressure style booth is that the exhaust air will take the path of least resistance, or, in the case of improperly designed (too small) exhaust duct sizing, wherever a leak may exist. So getting back to the "what materials" question, it may fill your garage with isocyanates for yourself or another family member to breathe, creating health hazards. Likewise, it may be forcing flammable vapors within the structure such that a very real explosion hazard exists from any electrical device, not just the fans. Is this taking place in a garage attached to the house? Now you could risk introducing these same hazards inside your home. The fan(s) need to be properly sized that it accomodates removal of these hazards while also considering the cfm introduced by the spray equipment. Most commercial booths that I am aware of draw air into the booth, just as your example picture shows, to better collect/remove any such hazards from the area, and duct it to an outside area where it can dissipate.

Your sandbox, your health, your family. Do as you wish, but think about the consequences. IMO you have given insufficient insight to what you are actually doing and with what paint products for anyone to actually give advice tailored to the situation at hand. What worked for someone else may be less than ideal for your situation, not knowing exactly what that is..

 

[atotalnincompoop]

IMO you have given insufficient insight to what you are actually doing and with what paint products for anyone to actually give advice tailored to the situation at hand. What worked for someone else may be less than ideal for your situation, not knowing exactly what that is..

somehow i guess i missed those questions, oops
the kind of stuff i plan on painting are car parts, i have some gas pumps, so parts from those, perhaps my coke machine, you know regular garage type stuff, nothing that would require any exotic paints, probably just spray some type of enamel or even rattle cans.
i would just like to contain it instead of ovcerspraying everything in the shop.

i should add that i may even want to use it for spraying powder on items i want to powdercoat.

 

[jeffzwoodie]

I do have a 6x8 3 wall paint booth with fan and proper lighting that i am going to sell but i think thunder bay is a ways from norco, ca

 

[cityhick]

Paint fumes are not nearly as flamable as most people think. I have been painting motorcycles is my garage for ten years now for some side money and the fact that I just enjoy making bikes look pretty cool. I have always just put a box fan in the window blowing out and since most folks want thier bikes done in the winter I always have the hanging garage furnace going to and its natural gas with rows of open flame. But you didnt hear that from me. Plastic has a static charge to it also and overspray and dust clings to it which is a good thing. When it gets to dirty just strip it off and replace it

 

[Falcon67]

It's not all about the flames - you want enough air in moving through there so that you can use a good mask and suit and maybe not require a fresh air mask. Still - build it as positive pressure if you are on a budget. Good booth exhaust fans cost big bucks.