Painters, Q on Air Requirements

[Crazy68Dart]

This was posted over at Moparts... but as usual no hits....

Hey all. I have a few questions for the paint/body guys on air requirements.

I have a 60 gallon single stage IR compressor. Plumbed from it is 1/2 black iron for about 30' underground, comes up into the garage. I then step down to a 3/8" size to the input of the dryer and then to regulator. Currently at the output of the regulator it then steps down to 1/4" to hook into the female part of the quick disconnect. I am currently using 3/8" goodyear hose. All of my quick disconnects have 3/8" NPT, but the inlet is pretty darn small, looks to be 1/4" hole. My air tools all have them, and I have always wondered if that is ok. It seems that is what most places sell.

Anyway, what is necessary for an HVLP gun to operator properly? I have not looked at any close, but what do they generally use for the quick disconnect?

The smallest opening in the system is going to cause a restriction, so if the gun does not use anything bigger than what I already have setup, I should be good to go, right?

I have a little more to add, but will wait for some responses to this first. Thanks!

[azz7772]

you should be good to go with that but i would add a water trap as well as the dryer..... a paint gun only needs  around 50/55 lbs of pressure

[Crazy68Dart]

you should be good to go with that but i would add a water trap as well as the dryer..... a paint gun only needs  around 50/55 lbs of pressure

Ok... what is the difference between the two?  Maybe I am not calling the part correctly.  What I call a dryer does trap water...

[azz7772]

yes it does trap water but the more water you get out of your system the better especially on a small compressor because it will run more and create heat which will create water.

[GTS225]

Oh, my!   That 30' of underground is going to act like an active air dryer.  Maybe I'm thinking too far into it, but if the moisture condenses in that underground piping, and has no way to get out, I would think it may freeze and split your pipe, or rust it out prematurely.

On the plus side, it probably does a decent job of drying the air before it gets into your shop.  I would imagine you don't have much, if any, problems with moisture in your paint gun or sandblaster.

Roger

[PinkE]

I'm thinkin Eldubb will have an answer for ya.  I think that underground line should have an evaporator on each end, the warm air coming out of the compressor is going to sweat as soon as it hits the underground line, then when it cools and comes back out into a warm room it will get warm, and cause more moisture...Prolly depends what temp your gonna paint at, right now might not be too bad, but in the winter it may cause problems.  I would use several evaporators just to be safe.  JMOpinion...

[Crazy68Dart]

I'm thinkin Eldubb will have an answer for ya.  I think that underground line should have an evaporator on each end, the warm air coming out of the compressor is going to sweat as soon as it hits the underground line, then when it cools and comes back out into a warm room it will get warm, and cause more moisture...Prolly depends what temp your gonna paint at, right now might not be too bad, but in the winter it may cause problems.  I would use several evaporators just to be safe.  JMOpinion...

Ok, and an evaporator is?? .  Sorry, I think we all are talking about the same thing, with different naming... maybe not.

Roger,  As far as the pipe goes, it is black iron.  When I dug the trench with my bare hands, I made sure to create fall back towards the compressor, so water would not lay in the pipe.  At the compressor I have a drop in the line, where I have a valve to drain the pipe, and can also drain the compressor tank separately.

I am a little confused now with what the difference between an evaporator, dryer, and water separator are... hmm.

The main reason for the post was to see if my volume would be ok to supply the gun.  All my air tools seem to work fine, and I am sure it takes a heck of a lot less than those.

[PinkE]

It's that glass thingy that catches the condensation in the lines...Some call it an evaporator, others call it a dryer, others call it a water seperator, and others call it a Thingy.... ...It's the same device....All I know is that you shouldn't rely on the one that is built into your compressor (Mine has one) and it should be away from the compressor by 6-8 feet, depending how long your lines are.  You want it away from the heat source (the compressor)...

[eldubb440]

i keep the drain (petcock) in the bottom of my tank cracked slightly open, so water never accumulates in my compressor.  my pipe runs stright up about 6 feet before it turns into the shop. i use a seperator, but get very little water out of it.  i NEVER have a water problem.

[Crazy68Dart]

My compressor is at least 30' away from my garage.  It is in another building, which is lower that my garage, so I get plenty of fall on the underground line.

Now that I understand the nomenclature, my dryer and regulator are in the garage after the 30' of hard line. Immediately out of the regulator is the 3/8" rubber hose.

The water trap in the line is near the outlet of the compressor tank in the other building.  It is to drain any water that might be in the line, but I have not ever drained anything significant.  Any water that I get is usually at the tank.  There is no dryer on the compressor itself.

So, as far as the original Q goes, seem like everything else is ok?

[azz7772]

sounds like your good to go.......post some pics when your done i am interested how it turns out for you another tip is wet your floor down prior to spraying that way you will not have dust flying around from your feet and hose sliding around on the floor.

[sweatybetty]

your lines should be fine. an hvlp gun only needs about 10-15 psi. Hi Volume Low Pressure. when you are ready to paint buy a new 3/8 hose and a couple of the disposable filters. i put one on the inlet end of the new hose and one right before the gun. this keeps the hose dry and clean and the next is just extra protection. ANY oil or water will mess up things fast. the paint dealer will have the filters..i run the regulator before the hose at about 90 psi and the reg at the gun at about 12 psi and it was all good

[Lars]

You should be OK, read this.

http://www.loehle.com/Loehle%20Aero%20Coatings/Ask%20Mike%20-%20Paint%20Tips%20Corner/spray_gun_tips.htm

[Midnight Special]

A double stage trap will work just fine.  Prior to your gunm ise a desicant filter and a round paper filter.  (The dessicant absorbs any additional vapor that may passed thru and the round paper filter will be a final trap just incase).

I painted the dart with a 5 Hp 21 gallon using a Sharp T-1 HVLP(Higl volm[for paint]using low air pressure).  The area of 40-45 with the sharp is really sufficant.  You might have to wait for the air vol to catch up with you time to time.  I have found, that if you use a BC/CC System or even a single stage soild color, adding an additional 10-15 % of a reducer will vastly improve flow.(At least with Sikkens and Dupont Chromabase paints).  As an example, if your using 8 oz of chroma base since its 1:1 ratio. additional 10-15 % of a compatible reducer[8 oz Cbase/8 oz base maker/ 1.5 -2.0 oz of reducer.].  It lays down so purddddddddy.

DISCLAIMER:Always shoot a pattern to see wher your fan is and how its laying down.

[BIG DOG]

I'm going to get flamed for this because I know alot of you do this including me in the past.Don't wet your floor down befor you paint! The extra moisture or humidity from wetting your floor down will cause you to have problems with you paint .
"Your Painting area needs to be bone dry. Any moisture evaporating up from the floor will pass through the space at the end of the spray gun... remember the spray gun? When you pulled the trigger, the pain/clear got real cold? The evaporating moisture from the floor turns some of the hardener into plastic beads on its way to the car. Geez! I got a lot of dirt in my finish. (Nope! You put a lot of “dirt” in your finish.) This doesn't hurt the paint and the paint store dudes win love you because you'll spend extra bucks buying sandpaper and compound to make SHINY HAPPEN. "

Check this out.http://www.neilslade.com/Papers/Painting.html

[sunsetdart]

You must remember that for every foot of hose coming from the outlet to the gun , you will drop 2 lbs. of air pressure. So if your hose is 50 ft.long, your pressure drop will be 10 lbs. at the gun. So if the pressure needed at the gun to spray is 50 lbs, you will need to dial in 60 lbs. to compensate for the drop in length of hose. I would also have a pressure dial at the gun, that will give you a direct reading of the pressure coming from the compressor.