Spray Room Design

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Posted · Report post

I am finishing up the rough design of my new workshop that I am putting in a 1,000 sq ft garage. I have left an 8 X 10 space for a dedicated spray room. I am a newbie and know diddly about spray room design so I am looking for some recommendations.

My plan was to put a two 3' doors as a French door in one end with drop-in filters in the doors and then put a wall-mounted exhaust fan in the other end which is an exterior wall. I don't have a clue what size will be required for the exhaust fan. I also know some say you absolutely need an explosion proof fan while others say they have been just fine with a conventional fan. Sooooooo, please let me know your thoughts (including how you would optimize the interior of this room-- fixed bench or fold down, work holding/hanging ideas, etc.)

Jim

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Posted · Report post

If I was going to use a room I'd use a false wall like a real booth. My booth is made compliant. If you run over to their web site there is a pic that shows the back filter wall as a wire frame photo.

Don

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Posted · Report post

The explosion proof fan is most critical if you spray anything other than waterbased products. I plan on utilizing some rubber walls on pivoting barn door hardware. When I get around to building it, I'll be sure to blog it, too.

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Posted · Report post

Bob Flexner talked once about making a fan that eliminated the explosion issue. The blade is on an axel with a pulley. The other end of the pulley is on a motor, out of range of the path of flammable material. This eliminates the fire issue and it also makes it cheaper to change fan blade if it gets covered with finish.

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Posted · Report post

Bob Flexner talked once about making a fan that eliminated the explosion issue. The blade is on an axel with a pulley. The other end of the pulley is on a motor, out of range of the path of flammable material. This eliminates the fire issue and it also makes it cheaper to change fan blade if it gets covered with finish.

Excellent idea, kinda like the old style pubs have for flashy fans.

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Posted · Report post

Jmadson, I like the fan blade with belt to a remote motor!

Dwacker, I don't know what you mean by a "false wall like a real booth", can you explain for this newbie?

Jim

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Posted · Report post

Jmadson, I like the fan blade with belt to a remote motor!

Dwacker, I don't know what you mean by a "false wall like a real booth", can you explain for this newbie?

Jim

A spray booth is just a tin box. Put into simple terms, it has two back walls. The inner back wall is just a grid of filters with a dead space of about two feet between the sealed back wall. The fan can go in the ceiling of the dead space or in the back wall. An 8x10 space gives you about an 8x8 or 10x6 booth. The axial tube fans are just as expensive as explosion proof fans. The issue with axial fans is you need the power to run them, the big ones used in most booths are 3 phase. If your booth is in a dusty space you may want to look at tacky filters for the door grid. Id use tacky filters anyways just so you dont have dust falling off the doors when you open and close them. Your door grid should be the same size as your back inner wall or close to it. The two left and right walls should be smooth, can even be drywall painted with latex paint. All you want to do is make a smooth surface so the overspray has les chance of sticking. All your lighting should be explosion proof behind tempered glass. All wires are supposed to be in conduit with the switches on the outside of the booth. Legally you have to have a air supply solenoid that cuts off the air supply to your gun if the fans are not running. You should also install a manometer. You will need this to know when your filters are plugging, as far as I know this is also required by law but really is a neccessity. Dwyer makes some very affordable manometers.

Don

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Posted · Report post

This is essentially what you are trying to build on the back of your room. This is just an exhaust chamber that is used to retrofit a small room for spraying.

exhaust-chamber_cat-01.jpg

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Posted · Report post

Wow, thanks for all the great advice. Turns out the spray room design is MUCH more complicated than I imagined so this is a real eye opener for me. Clearly I need to spend some considerable time thinking this out but thanks for all the good info that will help me get started!

Jim

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Posted · Report post

I'd recommend a positive pressure room, the fan blows clean air into the room through filters, and then out through filters on the other side. This doesn't require explosive proof fans, as the only thing the fan is blowing is clan air.

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Posted · Report post

Positive pressure booth's still need a explosion proof fan. They use two fans one is the exhaust and there is an AMU air make up unit. They also need temperature regulation of the AMU to prevent moisture contamination and pressure contamination. Excess pressure causes contamination issues to do flow imbalance. You still need a negetive pressure to create a vacuum at the exhaust.

Don

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