293 replies to this topic

[Rockoz]

It wont be a fire that causes the problem.

It will be an explosion.

The circumstances that are required for it to explode are pretty specific.

But given the right circumstances there will be enough explosive power to demolish the shed its in.

And possibly some surrounding stuff as well.

[slar]

Yes Im very wary of the risk....ive decided to use a 300mm drum extractor / blower.......use it to suck air through a filter and blow the clean air through a 5m length of ducting to the temporary booth.

Im going to attach a couple of strips of spray booth extraction filter to one wall of the booth......that should catch the particulates of paint and allow air flow out of the booth......I really need to keep the overspray trapped as the shed is pretty new and clean and would like to keep it that way.

 

The drum extractor is only $149.00 and can blow 63 cubic meters of air a minute.....my booth is 50.6 cubic meters so it should clear the booth relatively quickly.

 

that's the theory anyway lol

 

I painted the engine bay with out air flow and it did get fairly foggy but not too bad.......but it needs to be better to spray the body as its a much bigger job.

 

Any suggestions welcome

 

cheers Al

[Rockoz]

The only problem I can forsee with a positive ventilation system is getting the air back out.

Too much restriction on the air getting out and it will blow up like a balloon.

The filters will catch the paint particles ok but there will still be solvents being vented past the filters.

An alternative without going to flameproof equipment would be a belt driven fan.

They are used in some exhaust fans in commercial kitchens.

You can keep the electrics out of the potentially flammable atmosphere that way and then vent it outside to a safer place

[ben23]

As long as the fans use induction motors there is no brushes therefore no sparks. However avoid using switches on the equipment switch it from the power point. Even most pedestal fans use small capacitor start induction motors so there is no real drama there. Only possible issue I can see is from the zero speed switch inside an induction motor which open circuits the starting capacitor or start winding in a motor when it reaches operating speed. But that's one momentary spark compared to continuous brush-on-commutator sparking of a universal motor so the chances are reduced dramatically. In saying that flameproof is best of course but yes.

[Rockoz]

Wouldnt take the chance.

Ever seen the effects of a gas explosion?

And I do hope you arent an electrician.

[slar]

OK good advice.....I'm going to use forced induction through a filter into the booth then let the gasses free flow out through ducting to a 240ltr garbage bin with large holes around the bottom....mounted on the inside of the lid will be a water spray with a hose attachment....the idea being the forced air will move the paint particulates and iso's out the extraction duct to the bin which will be spraying water through the exhaust particulates catching most of it and washing it down the drain....this way the motor stays well away from the booth and iso's are attracted to water so should be relatively effective. Also should stop my booth blowing up like a Ballon under pressure lol....what do you think

[Rockoz]

Should work okay but you may need a speed control on the motor depending on how much air it pushes.

You will need to duct the outlet of the fan through the filter to the booth otherwise the air will short circuit around the fan and not go into the booth.

Washing the particulates down the drain may be in violation of some laws though.

How about filtering the exhaust and venting to outside into free air?

[Mort]

When you have it sorted Dave don't forget to post pics during the install and after you finish also a shopping list what you ended up using for the fan, ducting, filters, etc.

 

Might be able to some spraying at home myself then.

[Rockoz]

Only one other consideration that may require some thought is static electricity.

Give it a run using the spray gun empty and see if you get any static build up.

[slar]

Ok will do, going to put it together Thursday night...Friday night....will post pics and describe any problems or failures and successes

[Rockoz]

More concerned about the static build up on the plastic.

Some plastics are great for static build up, others are anti static.

Probably wont be an issue but something to be aware of and checked.

[Mort]

Damn, just re-read me post, was suppose to be Al, don't know why i typed Dave.    

[slar]

That's OK Bill lol

[slar]

As for static build up on the plastic.....I can't see it being too much of a problem as the booth is covered with masking plastic which is caroma coated to prevent any over spray from flaking off....same plastic you use to mask your car when painting so it works for that and should work for the booth.

A wire from the car body to the ground is good idea as well....used to do this when I was working in the panel game many moons ago.

[EunUCh]

Nice job,we just put a temporary booth up to do small stuff,we used one of those sawdust extractor thingies that are used on

timber sizing planes for extraction,just an idea but i think you are better off with a slight negative pressure in booth with a filter on the intake side so

that it acts as a "draw through",some hessian bagging as an exhaust filter will stop the solids but you will still smell it out side,if you 

use a big fan to pull the fumes out make the exhaust filter as big as possible,a slight mist of water on the exhaust will probably kill

a lot of shit and get trapped in bagging which can be replaced.just 2 bobs worth.

[slar]

Thanks mate all comments welcome.....some very interesting ideas coming forth

[slar]

Oki doki......put the temporary booth extraction system in and tested it today.....It ended up being a positive pressure system and it works really well.

I decided to stick with my water filter idea instead of mechanical filters because its a lot less pressure to force air through a spray than to force it through slowly blocking up filters..

 

Heres some pics of what I done.

 

First of all got an old garbage bin and cut hole all around the bottom with a hole saw....ensuring the total area of the holes is greater than the ducting area used on the inlet side of the booth.

I then went to the local hardware and bought a few garden watering system bits and pieces and made up a spray and fitted it to the lid right in the center.

 

The spray head......made it long enough to reach about half way down the bin and inserted a 360 deg spray tip on the end.

The exhuast ducting has to placed  above the spray head or youll fill your ducting with water.

 

Center the spray in the lid.......attached a normal hose connector to the inlet.

 

This is what it looks like connected up

 

Ok now for the inlet air.

This is what I bought to  make up my air supply. I bought some filter foam from Clark Rubber and inserted it on the intake grill....it pretty fine and has minimal air resistance.( no pic of that)

 

And 5m of 300mm expandable ducting.

 

This is how I connected it to the booth....I used an end cap off that rather large U shaped corrugated box drain and screwed it into into the upper corner of the booth.

Before I screwed it up I cut a hole on the middle of it and used a typical black plastic garden pot which was about 330mm in diameter.....I cut the bottom off the pot...screwed it to the box drain end cap and it made a perfect attaching point for the ducting because the side of these pots are tapered so I could put the ducting on and slide it up for a nice tight fit.......seal it off with duct tape.

 

Did the same thing for the exhaust at the bottom opposing diagonal corner. Used the same pot idea in the back of the garbage bin filter as well.

 

Made up a cowl for the intake to direct the air diagonally across the booth.

 

There you have it......works well.....it pressurizes the booth just nice and has a nice steady air flow.....I tested it out with a piece of smoldering cardboard and the system cleared the booth of smoke in just over a minute......it may not be as efficient as a pro booth but it will do me for the next few weeks while I smack some paint on RUSTY.

 

Cheers Al

 

 

 

[ben23]

Should keep that booth pretty clear id say. Looks like that water filter should work well too. Also Rockoz, I'm an auto electrician by trade but I have done a considerable amount of work with domestic electrical and in particular motors and generators. I know there is a considerable risk associated with motors and volatile/explosive environments. Done plenty of work with tankers and in the bilges of boats with inboard motors and that requires explosion proof alternators and starter motors. All I'm saying is that for an induction motor running continuously would pose no real threat as there is no sparking under normal operation. I don't recommend it of course, use flameproof/explosion proof equipment wherever you can, and if I was a mains electrician I would never supply/fit/recommend anything else for such an application. I was not recommending just pointing out that it's not as bad as its made out to be. It's up to the discretion of the OP to choose the method he wants. In the end he chose the best method by using positive pressure and not drawing the fumes through the motor. I appreciate your concern.

[Rockoz]

Ben.

No worries.

But there is a huge difference in the requirements for auto and mains.

I have done both.

What is considered flameproof in auto is actually a joke when compared to the requirements of mines, mills or gas plants.

Ive seen first hand the effects of a gas explosion that happened not too far from you about 35 years ago.

So I am a bit cautious on the subject.

Sorry if I offended you.

[Rockoz]

AL.

Looks really good. Will be interesting to see how it works.

Youve thought it out pretty well.

[slar]

Yeh it was the only way to keep the fan out of the fume flow without losing air capacity.....will be painting the backs of the doors tomorrow so I guess we'll see how it goes.

[HIBERN8]

You continue to impress me! Outstanding workmanship mate, it's a real treat watching your car come together. Very much looking forward to seeing some more colour

[slar]

Thanks Mark....well I done a bit of spraying today and tested out the water filter garbage bin.......It works a treat.

 

Check this out.....it certainly catches most of the paint particles.

 

 

And this is what I ended up with.......got all 4 door backs done....finally!!

 

 

Cheers Al