Questions for Multi-use air compressor setup including painting

[ttownthomas]

I moved into a new house in central NC about a year ago and I am finishing the garage as a shop. The insulation is done and the drywall is wrapping up this week and am now moving on to plumbing my air compressor. At the old house I just had the air line hooked right up to the tank and I, of course, had water problems. This time I want to do it right.

My compressor is: Porter Cable Jetstream CPLC7060V / 135 PSI, 7HP, 60 Gal, 12.1 SCFM Delivered at 40PSI and 9.7 SCFM Delivered at 90 PSI. The tank outlet is 1/2 inch

I want to use it for every thing from Impact Gun, to Pneumatic Sanders and To paint my project cars.

I have been reading threads for hours today and I have figured out some stuff but need help on others. I am going to use copper tubing for the lines and plan to run a single line (non looped). It is about a 12 foot run from my basement (where the compressor lives) to the garage and then I will install a T with a drain and go up and around the upper perimeter of the shop, around the corner and eventually to several "upside down J shaped" drops with drains at the bottom of each. I will get to my first drop at about 42 feet from the compressor. The next 2 drops will be about 46 and 52 feet from the compressor and I plan a drain line drop about 4 more feet past that.

Copper tubing is expensive but I also want to do it right.

What size tubing should I be using for the main line from the compressor and around the perimeter? Does it matter that the tank has a 1/2 inch outlet? Should I also be using the same size for the drop lines?

I know I "should" run the last long leg of the perimeter line on an incline, but is it ok to run it parallel to the ground and just put a small drop at the beginning to keep it below the high point?

Chris
Raleigh NC

 

[ttownthomas]

I guess I am not able to post without approval yet . While I'm waiting for my post to go live I found this link from another thread.

Compressed Air - Air Flow and Recommended Pipe Size

Pipe line sizing compressed air

www.engineeringtoolbox.com

The graph makes me think 1/2 in pipe is fine. There will be six 90 degree elbows before the long Line with the drops.

 

[ttownthomas]

And then I found this: https://www.powdercoatguide.com/2016/05/plumbing-your-air-compressor.html#google_vignette

Which makes me think it's right on the fence.

On anthoer note, 1/2 inch pipe adds about 8 gallons of volume and if I used the 3/4 it adds about 20 gallons to the total system capacity.

 

[Shiftless]

On anthoer note, 1/2 inch pipe adds about 8 gallons of volume and if I used the 3/4 it adds about 20 gallons to the total system capacity

I think you are way off on your calculation. You didn’t say exactly how many feet of half inch copper tubing you will be running but it takes about 80 feet to equal ONE gallon of capacity.
You aren’t running 600+ feet of tubing are you?

 

[The Cobbler]

1/2 " copper is good for most hobby set ups . especially if you make a continuous loop around the perimeter .
I ran mine below the outlets rather than making the outlets a drop . they pitch away from the feed with drains on the ends . that way any moisture stays in the main line and finds it's way to the lowest points .

 

[ttownthomas]

I think you are way off on your calculation. You didn’t say exactly how many feet of half inch copper tubing you will be running but it takes about 80 feet to equal ONE gallon of capacity.
You aren’t running 600+ feet of tubing are you?

lol...I guess I am way off.....Total will be 70-80 feet including the drops. I wonder where I am off.

My very rough math was: 1/2 ID=.545, Area = Pi r^2: .2725 X .2725 * 3.14 = .23316 inches = 2.8 cubic inches per foot X 70 Feet = 196 Cubic inches / 144 cu inches per foot = 1.36 Cubic feet x 7.5 = 10.2 US gallons...... I figured it was high so I knocked off 20% to 8

What am I missing?

 

[Steve_P]

I used 3/4 copper for mine, with the reason being slowing down the flow in that portion. Mine slopes slightly downward, away from the compressor, and runs down the wall and back to give it ~50' total. It then reduces to 1/2 copper for the regulator. I've posted a picture of the regulator section before. I get almost zero water in my water separator as 99% is removed by the dead legs with drains.

Sand Blasting . . .

So I've owned the Black Bull gravity fed sand blaster for about 5 years. It works "okay" but recently it's been really unimpressive. Getting more air out the gun then abrasive. Then I "jiggle the handle" and it works again as intended. I've kicked around the idea of a blasting cabinet, as this...

www.garagejournal.com

 

[Shiftless]

lol...I guess I am way off.....Total will be 70-80 feet including the drops. I wonder where I am off.


What am I missing?

Good work except for one error. Start with One foot is 12 inches.
one cubic foot is 12 cubed not 12 squared. So there are 1728 cubic inches in one cubic foot.

So you’re only off by a factor of 12 !!

 

[GeoBruin]

Keep in mind when looking at charts/graphs like those linked that the flow numbers you plug in need to be the flow to tool from the tank, not the flow of your compressor's pump. Your compressor may only make 10 cfm, but the air consumption of a tool can be 4 of 5 times that amount (or more!) and it's the air delivery to the tool that you're at risk of restricting. Also, keep in mind any hoses you'll be adding in addition to the hard pipe length.

 

[RTM]

My very rough math was: 1/2 ID=.545,

What am I missing?

You trusted the AI definition?

inside diameter (ID) of a 1/2 inch copper pipe is typically around 0.545 inches.

Explanation:

• When referring to copper pipe sizes, the "1/2 inch" refers to the nominal outside diameter (OD).
• A 1/2 inch copper pipe will have an actual ID slightly less than 1/2 inch, usually around 0.545 inches.

I was going to check your math, but this gave me too much of a chuckle. Maybe later

Table from copper.org says 0.0121 gal/ft, x 70 gives 0.847 gal. Make someone else do the hard math.

Copper Tube Handbook: Table 14.2b

Dimensions and Physical Characteristics of Copper Tube: Type L

copper.org

Other tables may have a slightly different value, based on min, max or mean dimension used.

 

[ttownthomas]

Good work except for one error. Start with One foot is 12 inches.
one cubic foot is 12 cubed not 12 squared. So there are 1728 cubic inches in one cubic foot.

So you’re only off by a factor of 12 !!

Lol....Cubed. Of course. Thanks!.

 

[ttownthomas]

You trusted the AI definition?

inside diameter (ID) of a 1/2 inch copper pipe is typically around 0.545 inches.

Explanation:

• When referring to copper pipe sizes, the "1/2 inch" refers to the nominal outside diameter (OD).
• A 1/2 inch copper pipe will have an actual ID slightly less than 1/2 inch, usually around 0.545 inches.

I was going to check your math, but this gave me too much of a chuckle. Maybe later

Table from copper.org says 0.0121 gal/ft, x 70 gives 0.847 gal. Make someone else do the hard math.

Copper Tube Handbook: Table 14.2b

Dimensions and Physical Characteristics of Copper Tube: Type L

copper.org

Other tables may have a slightly different value, based on min, max or mean dimension used.

Good ole AI. I was just trying to get in the ballpark. With my factor of 12 I was never going to be close.

 

[ttownthomas]

OK. Im going to make my main line 3/4. Im tired of doing math!

 

[NakeDiesel]

I do everything with my air system in my shop (painting cars/equipment/parts, sand blasting, air tools, etc.). Have an 80 gallon vertical 2 stage compressor that flows into a chiller using 3/4" hydraulic hose, then another hydraulic hose to my 3/4" black pipe. I've got runs all over my shop all with full pressure, I have one outlet that goes through a filter/regulator for painting. Each drop has a drain valve as well.

 

[dnschmidt]

What you're missing is that your compressor is TOO SMALL to paint complete cars. I have at least 50 spray guns, (collecting them and using them are hobbies of mine) and the average air consumption for a pro level spray gun (SATA, Iwata, DeVilbiss, Sagola, Walcom and most others) is 17 SCFM. I have a 5 HP Quincy that puts out 17 SCFM and it barely keeps up when I do a complete car. If I ever need another compressor I'm going 7.5 HP and likely an Eaton with the noise suppressor which is remarkably effective. Also, as small as they are air powered die grinders, belt files, Mud Hogs, Straight Line Sanders (I like Hutchins) and DA sanders (I use Hutchins, Dynabrade and AirVantage) are air hogs as well.

These air compressor threads come on this board at lease twice a month and in every one the OP thinks their compressor is big enough and in virtually every case IT ISN'T.

1/2" WILL WORK, 3/4 WOULD BE BETTER but since your air hoses are going to be 3/8" ID it really doesn't matter that much. Use Prevost European style high flow fittings (what are mistakenly called Milton V in America).

 

[Steve_P]

What you're missing is that your compressor is TOO SMALL to paint complete cars. I have at least 50 spray guns, (collecting them and using them are hobbies of mine) and the average air consumption for a pro level spray gun (SATA, Iwata, DeVilbiss, Sagola, Walcom and most others) is 17 SCFM. I have a 5 HP Quincy that puts out 17 SCFM and it barely keeps up when I do a complete car. If I ever need another compressor I'm going 7.5 HP and likely an Eaton with the noise suppressor which is remarkably effective. Also, as small as they are air powered die grinders, belt files, Mud Hogs, Straight Line Sanders (I like Hutchins) and DA sanders (I use Hutchins, Dynabrade and AirVantage) are air hogs as well.

These air compressor threads come on this board at lease twice a month and in every one the OP thinks their compressor is big enough and in virtually every case IT ISN'T.

1/2" WILL WORK, 3/4 WOULD BE BETTER but since your air hoses are going to be 3/8" ID it really doesn't matter that much. Use Prevost European style high flow fittings (what are mistakenly called Milton V in America).

Yep, that's more like a "5 HP" box store compressor, which means more like 4HP and probably 15A draw. But the question was about the line setup so I ignored that. If OP actually wants to do what he says, he needs at least a real 5 HP compressor that puts out 15+ CFM at 90 PSI. As you said.

The advantage of the 3/4 tubing as I said is that it slows the airflow down which allows the air more time to cool and therefore more time for the water to turn from vapor to liquid and drop into the dead legs. Sure, I haven't actually tested this to see the difference in water separation, but the cross-sectional area is more than doubled between 1/2 and 3/4.

Belt files use 20+ CFM during usage, and a RO sander almost as much. The specs listed by most manufacturers assume a random duty cycle, so they come up with ludicrously low figures like 8CFM. Dynabrade is one of the few that gives real numbers, and they're big numbers in comparison to the others.

 

[ttownthomas]

What you're missing is that your compressor is TOO SMALL to paint complete cars. I have at least 50 spray guns, (collecting them and using them are hobbies of mine) and the average air consumption for a pro level spray gun (SATA, Iwata, DeVilbiss, Sagola, Walcom and most others) is 17 SCFM. I have a 5 HP Quincy that puts out 17 SCFM and it barely keeps up when I do a complete car. If I ever need another compressor I'm going 7.5 HP and likely an Eaton with the noise suppressor which is remarkably effective. Also, as small as they are air powered die grinders, belt files, Mud Hogs, Straight Line Sanders (I like Hutchins) and DA sanders (I use Hutchins, Dynabrade and AirVantage) are air hogs as well.

These air compressor threads come on this board at lease twice a month and in every one the OP thinks their compressor is big enough and in virtually every case IT ISN'T.

1/2" WILL WORK, 3/4 WOULD BE BETTER but since your air hoses are going to be 3/8" ID it really doesn't matter that much. Use Prevost European style high flow fittings (what are mistakenly called Milton V in America).

Thanks for the input. More reason to do the 3/4 line. Then I wont have to re-do it if I upgrade the compressor.

 

[ttownthomas]

@dnschmidt

This spray gun set looks like a good match for my compressor. Would this not be sufficient to paint whole cars? What am I missing?

Devilbiss Auto Paint and Touch-Up System 802342

Includes full-size HVLP spray gun, mini detail gun, and more

www.eastwood.com

Plus the compressor is 20 years old. Were they over-selling the specifications as much back then?

 

[GeoBruin]

@dnschmidt

This spray gun set looks like a good match for my compressor. Would this not be sufficient to paint whole cars? What am I missing?

Devilbiss Auto Paint and Touch-Up System 802342

Includes full-size HVLP spray gun, mini detail gun, and more

www.eastwood.com

Plus the compressor is 20 years old. Were they over-selling the specifications as much back then?

If it says 7 horsepower, but makes less than 10 CFM, you probably have your answer.

 

[NakeDiesel]

My compressor is 20 some odd years old, it has a 7.5hp motor with I believe 26cfm output at 175psi. I just had to replace the large capacitor in it and have also replaced the auto drain and the unloader valve, just in the last few years. I run mine hard when sand plasting parts.