Simple Safe Spray Booth?

[raferguson]

I was not sure what forum to post this on, but here goes.

Anyone have any suggestions for a simple small spray booth? One that would be more or less sparkproof, for safety? This is not something that I would use often, but the last time I sprayed, I coughed for days, even with a respirator. Explosion proof is probably too expensive, especially for occasional use. I am thinking something like 2 by 2 by 2 foot, for spraying small pieces.

I actually have a book on my shelf about designing industrial exhaust hoods, my issue is more making it safe.

Perhaps a simple cheap fan would suffice, induction motors do not have brushes, and the shaded pole motors don't have a switch to cut out the capacitor. (I have a drill press with capacitor start, and you can hear the switch cut in and out). I could put the switch outside the booth, or even omit a switch, and just plug it in when I want to use it.

Applying the general rule of thumb for industrial hoods, I would assume 100 ft/minute at the face, so with a 2 by 2 opening, that would be 400 cubic feet per minute. Bathroom exhaust fans are more like 100 cubic feet per minute, so too small. Typical exhaust fans are too large.

I am probably making this all too complicated, but I do want it to be safe.

 

[andrewordrew]

In my opinion, you are over complicating the matter, but I’m not particularly picky when it comes to health and safety. I don’t spray enough at one time to overwhelm my respirator, and I’m rarely concerned of a spark igniting a fire in something like spray paint... in my experience, the unexpected will hurt you before the in-your-face stuff.

Would something like this suffice?

I would think the filter would do most of the heavy lifting, and help keep your paint job somewhat clean.


Sent from my iPhone using Tapatalk

 

[Falcon67]

If I needed something like a 2x2 paint booth, I'd go looking for a length of 12" or better flex duct. Attach to both ends, place a fan blowing in on one duct and use the other to route fumes outside. You could use heavy plastic sheet for the "door", maybe with a couple of holes for hands to enter.

 

[raferguson]

A few comments:

Sometimes I use an air brush, and that is when I had trouble with a cough. The air brush really atomizes the paint, so it hangs in the air. Lots of overspray.

I like the idea of a folding paint booth, thanks. That makes a lot of sense for something that would only be used occasionally.

Whatever I do, I want to push/pull the dirty air outside.

I am occasionally accused of making things too complex. ;-)

Looking around a bit more, a duct fan might work. In other words, attach the 6 inch hose to the booth, run it out the door, and then hook it up to a duct fan. The duct fan could be inside or outside. Duct fans seem to be available in about the right CFM. But is the motor such that it will not generate a spark?

Richard

In my opinion, you are over complicating the matter, but I’m not particularly picky when it comes to health and safety. I don’t spray enough at one time to overwhelm my respirator, and I’m rarely concerned of a spark igniting a fire in something like spray paint... in my experience, the unexpected will hurt you before the in-your-face stuff.

Would something like this suffice?

I would think the filter would do most of the heavy lifting, and help keep your paint job somewhat clean.


Sent from my iPhone using Tapatalk

 

[6PTsocket]

I would prefer a bigger both that you can work in. The filter is on
one side to keep dust out of the booth and the fan is on the other. This can make a big difference if you are outside. I guess a second filter on the fan would protect the fan from getting gunked up. I think I would go for more of a fabric and frame design; aluminum tube or PVC for the frame.

Sent from my SM-G900V using Tapatalk

 

[Lelandwelds]

If you set up your fan to blow instead of to ****, spark generation is much less of an issue. If you must ****, use a pulley instead of driving fan directly.

I use to paint in a factory setting. We used a roll filter with a very porous media. It was blue on one face and was much less restrictive than a throwaway HVAC filter. I would cut squares as needed from something similiar. I would build a frame similiar to a box kite and cover it with plastic sheet from the orange store. There is a plasticizers resistant packaging type tape out there for plastic.

 

[GirchyGirchy]

You don't mention using a respirator...that's the first step. Look on 3M's site and choose the correct filters and cartridges for what you're using.

 

[sberry]

If you set up your fan to blow instead of to ****, spark generation is much less of an issue. If you must ****, use a pulley instead of driving fan directly.

I use to paint in a factory setting. We used a roll filter with a very porous media. It was blue on one face and was much less restrictive than a throwaway HVAC filter. I would cut squares as needed from something similiar. I would build a frame similiar to a box kite and cover it with plastic sheet from the orange store. There is a plasticizers resistant packaging type tape out there for plastic.

A fan blowing moves air everywhere, a paint booth uses a fan to draw. http://finishingacademy.com/training/aero/aero_mod3/aero_mod3_intro.html Read thru this, its about booths. 3.3 has a good drawing about air pressure differential.

 

[johninct]

Get a forced air breathing system. A little expensive but what good is money if you don't have your health. I am not that concerned with safety, but when you said you coughed for days and only painting small items, my safety alarm goes off.

 

[sberry]

Nothing and no amount of equipment makes up for poor design. You cant blow paint out. Well you can but not where you want it to go. A booth or fume removal and ventilation is different than a clean room.
Put a small twin box fan in a bedroom window, open the main door to the house and experiment with the bedroom door and some incense to see how air moves, how much you need to restrict the inlet to get air movement.
Some designs may need to be different for heat makeup while painting. A well clearing enclosure wont have a problem with explosion ( some not so well don't either but) and more and more are water paints.
I can stand up wind in mine and actually spray without a mask if I wanted to, air all progressively moving toward the exhaust.
Fan pulls all the plastic closed, air comes in over the top of the end and in to a downdraft, dirt doesn't get kicked up from the floor and its very clean.
This same fundamental principle is used in all booths, large or small and a divided room helps, it is needed if heating equipment is used.

 

[Retlaw 66]

A couple of ideas:
-A squirrel cage fan from an old forced air hvac unit.
-Belt driven fan.
-Search Craigslist for 'fume hood'.
-Modify a range/stove hood.


Sberry.... I like those roll-up walls!!

 

[Lsversaw]

To build a small parts paint booth, I bought a Jet dust collector with a TEFC (totally enclosed fan cooled) motor that sits outside of the airflow. I should be double protected: the motor won't see any paint fumes, and TEFC motor is sealed. On this particular dust collector, the intake is a vertical duct that draws incoming air downward.

For the actual booth portion, I plan to (sorry, it's not built yet so I can't tell you how [if?] it works) use a cardboard box of the "RSC" (regular slotted container) type. The box will be 2' x 3' (that's the open sides) x 2' deep. I will mount the box to the dust collector with the 2' x 3' opening facing me and a 2' x 2' side down. I'll just cut a hole in the 2' x 2' side that's down, with the hole the same size as the intake duct. Then I'll set the hole in the box over the intake duct. At that point I'll have a 2' wide x 3' tall "booth", 2' deep, that sits about 3' off the floor. But it will need filters.

For filters I will use two 24" x 18" furnace filters, taped together to form one 24" x 36" filter. I may make up two of those 24" x 36" filters and stack them to get better filtration of paint particles. This won't filter out fumes, but with high-filtration furnace filters I hope it will remove particles.

The filters will be mounted vertically, facing the open front, about halfway into the 2' depth of the box. The exhaust duct will enter the box BEHIND the filters. I'll have a area 1' deep x 2' wide x 3' high in front of the filters for hanging parts being painted.

When the box and filters get filthy with paint, I'll just throw 'em away and replace with new.

If that description doesn't make sense, let me know and I'll post a drawing.

I'd appreciate any and all comments on this plan. Do you think it will work? If not, how can it be improved?

 

[Lelandwelds]

Nothing and no amount of equipment makes up for poor design. You cant blow paint out. Well you can but not where you want it to go.

A well clearing enclosure wont have a problem with explosion

I really like your booth. I will need to come back and study. The OP isnt building a booth. He's building what amounts to a tiny bench top sandblast rig with a different gun and media. He will probably stick his hands through overlapping slits instead of elbow length gloves. A Walmart box fan jammed up against one end would work because the volume and pressures involved are tiny. The problem is the operator is scared of "boom" not that he is being overcome by airbrush and tired of being rushed to the ER.

When you say" well cleared" , you're talking about explosive limits. Too low a concentration- no boom. Too high a concentration, no boom. Someone has already taken a thing like a bomb calorimeter and mapped out the narrow bandwidth of "boom" for every chemical out there.

Sometimes I use an air brush, and that is when I had trouble with a cough. The air brush really atomizes the paint, so it hangs in the air. Lots of overspray.


Richard

Listen to Sberry. He actually owns a spraybooth. I just worked in one 40 years ago and hated it. I did not spend much time examining motors I could not see. If the thing blew up, some days I probably would have welcomed it.

I used to sell CO2 to an artist. His rig was modeled on the laminar flow rigs out of UT . I think it was updraft. Parts set on a grid like used on old flourescent lights. He had upper and lower friction fit plexiglass doors that he left wide open. He used roll material actually mfg for paintbooths top and bottom. The filter was held against a wire screen by wires poking through filter and twisted around the screen. He used to go on and on about how his secret was straightening the airflow out.

 

[oldn_rusty]

A friend started with a refrigerator box, added a shelf, light and exhaust fan. He could paint items as large as an 18" wire wheel. Had storage below the shelf. Mounted the whole thing on wheels so could wheel it into a corner when not used. After a few uses, it is an easy move to replace the box and do version 2...

Good luck,

 

[sberry]

A fan from a dryer clears the smoke in this booth. I have used them from microwaves too.