Black pipe 1/2" or 3/4"?

[Scoutman]

I have been wanting to plumb in hard lines to my air compressor for a while and I'm starting to gather up the parts to do it. My compressor is an IR 60 gal with a single stage compressor and a 1/2" outlet valve. I was originally planning on 3/4" black pipe but now I'm wondering what the extra cost of it is over 1/2" and would I notice a difference? I'm only talking about running it to a couple of drops to reach the second and third bays in my 3 car 23'x32'. Tools used are the common 1/2" impact, die grinder, tires, plasma, etc. Does 1/2" make more sense or is the overkill worth it?

Please don't bring up any other materials.

 

[CitadelBlue]

Can we assume 'black pipe' is the pipe usually used for natural gas lines?

 

[Scoutman]

Can we assume 'black pipe' is the pipe usually used for natural gas lines?

Yes I suppose that's what it was for. It's the same black pipe that folks use for air lines that you can get at Lowes or similar.

 

[theoldwizard1]

What is the CFM of the compressor ?

1/2" is probably fine for everything except sand blasting. Typical air hose is 3/8".

 

[Scoutman]

What is the CFM of the compressor ?

1/2" is probably fine for everything except sand blasting. Typical air hose is 3/8".

Looks like it's 10.3 cfm at 135 psi. I think my Reelcraft hose reel is 3/8"

 

[pattenp]

I have similar size garage and ran 1/2" air line for about 30' with two drops. I use it for the same things you listed and it works good for me. I don't think up sizing the line to 3/4" will be of any noticeable benefit for your use.

 

[C96]

Although ½” would most likely be adequate for your situation, I would run the main trunk line using minimum of ¾”, then branch off for the drops using ½”.

Glad to see you are going to use the black iron pipe. Does a great job dissipating the heat, makes a strong and firm installation especially at the service points.

 

[Wingnut65]

3/4" lines also offer more capacity to the air system. Kinda like getting a little bigger storage tank

 

[Scoutman]

Although ½” would most likely be adequate for your situation, I would run the main trunk line using minimum of ¾”, then branch off for the drops using ½”.

Glad to see you are going to use the black iron pipe. Does a great job dissipating the heat, makes a strong and firm installation especially at the service points.

The black pipe just makes sense for the short runs I'm going to make. I looked at some of the air line kits and I would have a lot of hose left over and still have to buy a few drops and pieces which starts losing it's value to me. I'm going to be doing this in stages so the pipe allows me to do that pretty easily as long as I have a plan.

 

[Scoutman]

3/4" lines also offer more capacity to the air system. Kinda like getting a little bigger storage tank

I would agree with you but the space is uber small. I ran a few quick numbers and assuming a total of 50 added feet of 3/4" line would only net me ~1.14 gal of added capacity.

 

[bochnak]

https://www.tptools.com/tech-metal-piping.dlp

These guys recommend 1/2" up to 75'. I plan on piping mine soon and will use 1/2".

 

[MFolks]

If the pipe is Chinese made, be prepared for leaks. If it were me. I'd get a set of taps and dies, and re-do the mating threads, and use pipe dope(not tape), when assembling the pipe sections.

 

[Scoutman]

If the pipe is Chinese made, be prepared for leaks. If it were me. I'd get a set of taps and dies, and re-do the mating threads, and use pipe dope(not tape), when assembling the pipe sections.

I was learning that last night when I was doing some reading on here about how folks have assembled their air systems. I looked at the sticker on the piece of 3/4" that I bought a few days ago (for another project, not air related) and it's made by Southland and says made in Mexico. I guess that's better than China.

I have some pipe threading equipment, dies and such but I'm not sure what sizes I have. I'll have to check if there's a 1/2" or 3/4".

 

[mikefromme]

Everyone has their favorite way to seal black pipe -- I've tried most everything; the easiest to use and hardest to mess up is Loctite 55... It has been discontinued in the USA but still available on ebay.

 

[Scoutman]

There was a thread on sealants that I found on here that discussed the different types. I'll probably use some flavor of pipe dope and not the T. Tape I've used in the past for brass fittings.

 

[mechan]

If the pipe is Chinese made, be prepared for leaks. If it were me. I'd get a set of taps and dies, and re-do the mating threads, and use pipe dope(not tape), when assembling the pipe sections.

Tape and dope is used together on carbon ...

 

[OccupantRJ]

I used 3/4 in my system, With 1/2 drops for general use, but I am also running air to two blast cabinets. I think 1/2" would do fine in your case. I have worked in a 27,000 sq ft factory with 3/8" steel pipe branch air lines, and they did surprisingly well for general air use. Here is the link to my system if you want to peruse it for ideas.

http://www.garagejournal.com/forum/showthread.php?t=227948

 

[Scoutman]

I used 3/4 in my system, With 1/2 drops for general use, but I am also running air to two blast cabinets. I think 1/2" would do fine in your case. I have worked in a 27,000 sq ft factory with 3/8" steel pipe branch air lines, and they did surprisingly well for general air use. Here is the link to my system if you want to peruse it for ideas.

http://www.garagejournal.com/forum/showthread.php?t=227948

Good thread, I had not seen that one yet. Picts always help too when laying things out. Thanks

 

[kbs2244]

You have to balance PSI and volume to be used.
The problem is flow friction.
I would go with the 3/4 for the whole system.
The up front extra cost is not that much and it will head off any possible future problems.

 

[volleyball]

You run and number of users means 1/2" is plenty. Spend the bucks on thread sealant. Loss from all those fittings add up.

 

[KCarGuy]

I was Lucky...
A Friend and Neighbor, brought over a Boat Load of Black Pipe, Threader and Vise Stand.
We Spent a weekend cutting, threading and assembling my Air line throughout my Garage.
Its Overkill...1" all the way around with 1/2 drops on each wall. Along with drip legs and drains.
I also have a Quick Connect out the front wall of the Garage.
And he only charged me Beer!

 

[EOC_Jason]

Check your local plumbing wholesaler. They are probably cheaper than a big box store. I got a long piece and just cut it in the parking lot before taking it home.

I used 3/4" just because, as others have said it also adds capacity. I painted my pipe before putting it up, then just had to do a little touch-up. Also used pipe dope on the fittings.

 

[sberry]

At 100 # you would save about .2 or less pressure drop at 100 ft with 3/4 vs 1/2 using a 1/2 impact. I use 1/2 drop and 25 ft of 1/2 hose with 40 cfm blaster. I like to work with the smaller pipe so much better and 1 size fitting makes it easier.

 

[600SL]

I used PVC not recommended for cold temperatures but I had it for about 15 years in CT.

After I installed it I went to McMaster Carr to order fittings and there were warnings on every page not to use PVC for air lines. Those warnings are no longer there. The issue was brittle and explosive failures in cold weather. How cold, I don't know.

 

[sparky7]

I used 1/2 but now wish i used 3/4 or 1

 

[sberry]

I got to ask,,, why?

 

[OccupantRJ]

Check your local plumbing wholesaler. They are probably cheaper than a big box store. I got a long piece and just cut it in the parking lot before taking it home.

I used 3/4" just because, as others have said it also adds capacity. I painted my pipe before putting it up, then just had to do a little touch-up. Also used pipe dope on the fittings.

My local distributor now has Chinese pipe. 21 foot stick was same as two 10 footers at Lowes. Got the 10 footers for handling reasons.

 

[kyrbz]

I'd be sure to have filters at your point of use. Moisture in the lines causes a lot of rust and crud to develop in black pipe.

 

[akdiesel]

I'd be sure to have filters at your point of use. Moisture in the lines causes a lot of rust and crud to develop in black pipe.

This is why you need to clean you air before it gets into your main line. Better for your pipe, better for your tools, and just better all around.
Tape and dope your threads. Tighten till you can not tighten no more. Leave room for expansion. Black pipe is the hardest to add to. In other words buy some extra "T's" and install them every 20 feet for future needs.

 

[j-guenth]

loop the pipe

 

[volleyball]

When I put in my pipe, I used T's and plugs for expansion. I also include unions.

 

[kyrbz]

This is why you need to clean you air before it gets into your main line. Better for your pipe, better for your tools, and just better all around.
Tape and dope your threads. Tighten till you can not tighten no more. Leave room for expansion. Black pipe is the hardest to add to. In other words buy some extra "T's" and install them every 20 feet for future needs.

I have a compressor with an aftercooler,moisture traps and a drip leg before entering my black pipe runs. Still get moisture in the lines during hot midwest summer humidity. Thats why I have additional filters at point of use including a Motoguard M60 sub-micronic filter in my spray booth.

 

[rodm1]

If you can buy US or Canadian pipe and fittings. The chines stuff leaks and will rust out fast. I've had the best luck using 3 wraps of tape starting 2 threads back, with pipe dope on top of that.

I've had good luck buying US pipe from the local LP company's.

http://columbiapipe.com/Default.aspx
http://www.galloup.com/

 

[scottbob]

Where are you putting regulators...if you're using them? Putting separate regulators close to the point of use can make a big difference. In my opinion high pressure on 1/2" is better than low pressure on 3/4". Also when you get your valves make sure you get full port ball valves...you can buy 1/2" valves but the hole in the middle may only be 1/4" or 3/8"


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[Scoutman]

I'll check the valves before I buy them but chances are they will only be on the drop legs below an air chuck to drain the water out. I'll probably put a barbed ****** and a hose in the bottom part of the valve to be able to point the hose outside the garage door or into a catch cup when I drain the line.

I'm not talking about a whole lot of pipe here. From the compressor I may have 25-30' of horizontal pipe. The verticals would be ~6'. I have no need to loop the pipe at this time. I will put in some extra T's with plugs for directions that I could expand toward and a few unions will be in there somewhere to help assembly.

Regulators, I usually don't need regulators for the stuff I run. If I'm using a HVLP gun I have an inline regulator and the plasma cutter runs in the range that my compressor puts out so I don't bother.

Filters, I have a detached assembly that is a water separator piggy-backed to a M-60 filter/dryer that I use for my plasma and painting. It's on quick connects so I can move it wherever it's needed. If I see that I'm getting a lot of water out of my drops then I'll consider putting a hard mounted water separator at each coupler.

So why use both T tape AND pipe dope? I don't mind doing it cause it's a cheap step but I was just wondering why not just dope?

I have to go to Lowes tomorrow so I'll see what the prices are on each size.

 

[LifeLongWNYer]

Just to satisfy my own curiosity, why doesn't anyone recommend copper for air lines? I ran 3/4" copper in my old garage and had no problems.

Getting ready to build a new one, and don't want to do anything that is wrong.

.

 

[Scoutman]

Just to satisfy my own curiosity, why doesn't anyone recommend copper for air lines? I ran 3/4" copper in my old garage and had no problems.

Getting ready to build a new one, and don't want to do anything that is wrong.

.

There are plenty of folks here on GJ that recommend copper. For me I wasn't interested in it due to cost and its more involved to assemble. There is certainly nothing wrong with going that route.

Since all I was interested in was black pipe, I was limiting discussion to just that material.

 

[akdiesel]

Scoutman

All the brass ball valves will be full bore 600# WOG rated. NO issues there.
As for you water drains, I do not recommend holding a cup or bucket to catch the little amount of water if any. You will get sprayed. You could simply blow it out to the floor and it only takes about a second or two.
The top three choices are Black pipe, copper and the aluminum vinyl wrap. Stainless is another option.

 

[Scoutman]

Scoutman

All the brass ball valves will be full bore 600# WOG rated. NO issues there.
As for you water drains, I do not recommend holding a cup or bucket to catch the little amount of water if any. You will get sprayed. You could simply blow it out to the floor and it only takes about a second or two.
The top three choices are Black pipe, copper and the aluminum vinyl wrap. Stainless is another option.

Every time I blow out my tank valve there is about a cup or so of water and it's pretty nasty stuff. If I just blew it out on the ground it'll be everywhere, sprayed all over the walls, and just a mess. I usually keep an old cup around and very slightly crack the valve to get the water out till clear air flows.

 

[shooting4life]

There are plenty of folks here on GJ that recommend copper. For me I wasn't interested in it due to cost and its more involved to assemble. There is certainly nothing wrong with going that route.

Since all I was interested in was black pipe, I was limiting discussion to just that material.

When I did my garage last fall and compared the price of 1/2" copper and 1/2" BIP the price was actually very similar. I went with copper because it was easier to modify at a latter date and install without a pipe threader.