Another Shop air piping question....

[rjprice]

So, I'm going to do copper for my 40x50 shop. Most of the drops will be on one 50ft side with one reel on the other 50 ft side. I have a 5hp, 60 gal CH compressor. ~10cfm @90psi

For the big pipe, is 3/4 good enough or do i need 1 inch?
For drops, I was thinking 1/2 pipe with high flow chuck and a drain for each.

I've sweated a few joints before but wanted to ask if I need to sweat all 3 joints in a tee fitting at the same time. So I should not solder the 1/2 drops later after doing the big pipe? also, it would seem I could assemble the drops on the bench then solder to the tee. Right?

 

[sberry]

1/2 pipe is good enough, a single size of fittings makes it even easier.

 

[Beau Nugget]

I just finished doing the same thing with copper in my shop. I used 3/4”. So far so good.

My under understanding is that it is best to sweat all the holes in a fitting at the same time so you don’t put the copper through multiple heat/cool cycles. I didn’t do this on 100% of my fittings but it’s holding pressure so far.

Yes, It seems like a good idea to assemble the drop where it’s easier to work on, then solder it to the T.

 

[matt_i]

Personally I'd stick to 3/4" just for more common fittings, lower cost. But, it is your shop and going to 1" is not going to hurt a thing. It will however require more heat into the joints.

If you have a specific need which is using "max air" like a blast cabinet or a large air tool, you can always upsize the piping going to that area. Otherwise using air to clear surfaces or inflate tires or impact tools can go on the 1/2" dia.

Its my opinion that your job goes easier when you solder all the fittings at once. You conserve heat because of course the copper conducts it which is a preheat to the next fitting.

The absolute most important task is not to burn down your shop with the torch when working near framing or various types of insulation. Next task is to not melt insulation off existing wiring, etc. I go and get a 10# extinguisher and set it right next to the job, because the time you'd need to go hunt for the extinguisher --if there was an immediate need-- is time you cannot afford. Enough said.

I recommend Stay Brite #8 solder (JW Harris mfg) and Stay-Clean flux. It is more expensive but like many things in life the result of that extra investment is that it works much easier and you get stronger joints to boot.

 

[sberry]

A 3/8 hose will drain that comp in a couple minutes and a 1/2 pipe will deliver 5x what it will make and run a 3/4 impact at 75 ft. Sandblast doesn't take a large line, it takes a large comp.
3/8 hose on a real hooked to blasting would serve 2 of those comps. 10 cfm is about 2.5 hp

 

[matt_i]

Just want to add, if you decide to sweat a tee "twice" don't bother cleaning the entire part because you will have to do the remaining part later after a heat & cool cycle and it oxidizes again.

 

[mike93lx]

For what you have described, 3/4 is money wasted. You would need to get a far larger compressor and really high demand tools for 1/2 to be too small. What's the likelihood of that happening?

 

[signcrafter]

What size outlet does your compressor have, probably 1/2". I'm doing the same thing except I'm using black pipe. My compressor is similar to yours and 1/2" would have been just fine. But cost difference wasn't much between 1/2" and 3/4" so I decided to plumb the main lines with 3/4" and then do 1/2" drops. It's overkill for what I have but it will be setup for if I ever get a bigger compressor. Now, if 3/4" was twice as expensive as 1/2" then I would have probably done all 1/2"

 

[sberry]

Yes, sometimes the cost is minor. The main advantage of 1/2 is simply less steps of reduction needed and some velocity increase may be helpful in driving condensate along.
It's good for larger comps, really doesn't matter much about the comp size but the demand. If you were going from 3/4 drive impact to inch drive for semi wheel work then it would require 3/4 line depending on length. For multiple users or long lines,, 100 ft + inch might be practical.

 

[lis2323]

Like most everyone else mentioned 1/2” would be more than adequate.


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[pancho400cid]

1/2" is probably fine as said.

3/4" is overkill... so that's what I used.

1" is waayyyy bigger than needed for a 10 CFM system. For that application, it is a waste of time, material and money.

 

[sberry]

The modern connector is rated 74 cfm. I am not sure what the loss is at that rate. A heavy 1/2 air gun is probably in the 25 cfm range. This is about the max draw most shops in this class use with some very minor exceptions. Sandblasting with the comp in this thread is less than half that and would lose 10# max thru 50 ft of 3/8 hose, nothing at all to work effeciency. 1/2 copper pipe is prolly 3 times the size that hose and could use 4 for friction math. Only use a couple # thru that part of the circuit if you wanted to blast longer than a couple minutes. I blasted a lot with the jet being an A auto air connector from my 3/8 hose reel. If you really want gains cheap shorten the hose from 50 to 25, 1/2 the loss. Gain 20# on a 1/2 air gun,,, changing the main from 1/2 to 3/4,,, 2# difference,,, ahead of any regulation.

 

[sberry]

The material cost for some of it between 1/2 and 3/4 is rather minor, inch starts to cost more especially compared to 1/2.

 

[bczygan]

The material cost for some of it between 1/2 and 3/4 is rather minor, inch starts to cost more especially compared to 1/2.

I was thinking I needed 3/4" for my main line.

But then I used a pressure drop calculator.

I based this on an 18CFM compressor, type L copper, a 100' of line, and a PSI of 150.

For a 3/4" line, the pressure drop was .283PSI.

For a 1/2" line, the pressure drop was 1.76PSI

Neither of these are objectionable.

Even at 100PSI, the results are and .425 and 2.63. Not a lot.

This doesn't account for turns, which must do a lot more than just length. I'll check that out.

Bill

 

[Lucky13driver]

I ran 3/4" on a loop all the way around the shop. I went with 3/4" because it would be covered up with Sheetrock and if I wanted to run things like a media blaster or upgrade the compressor I didn't want have to open up the walls to replace the pipes, the cost difference was minor.

 

[ez-duzit]

3/4" copper mains with 1/2" drops is what I have for my smaller shop.

 

[sberry]

It's not really based on compressor size but tool demand. This is likev saying I need a bigger outlet than 20A because I changed the breaker on the main from 100 to 200. Loss in "media" blast is actually less relevant than impact tool.

 

[sberry]

I was thinking I needed 3/4" for my main line.

But then I used a pressure drop calculator.

I based this on an 18CFM compressor, type L copper, a 100' of line, and a PSI of 150.

For a 3/4" line, the pressure drop was .283PSI.

For a 1/2" line, the pressure drop was 1.76PSI

Neither of these are objectionable.

Even at 100PSI, the results are and .425 and 2.63. Not a lot.

This doesn't account for turns, which must do a lot more than just length. I'll check that out.

Bill

Where and what you have to run that any of this matters? But again doesn't matter if you have 200 cfm compressor if you gonna hook a 10 cfm tool to it.

 

[mcbane]

Here is a pressure drop calculator: https://www.engineeringtoolbox.com/pressure-drop-compressed-air-pipes-d_852.html

Use it to figure out whether any plumbing configuration will give you acceptable losses. Note that if you run unregulated air in the distribution system and then regulate pressure at the point of use you likely will never notice a few psi being lost in your plumbing.


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[bczygan]

Where and what you have to run that any of this matters? But again doesn't matter if you have 200 cfm compressor if you gonna hook a 10 cfm tool to it.

The point is that the pressure drop for the 1/2" lines isn't very much.

Bill

 

[uscarry45]

Go with the 3/4. You will be glad you did. The 1/2 would work fine until you decide you need a bigger compressor. I wish I would have gone bigger

 

[sberry]

The point is that the pressure drop for the 1/2" lines isn't very much.

Bill

This is true. Its also true that some charts like Pex publishes are for 60 ft which is a lot closer to the actual length of the circuit. Its a little like wiring, its often assumed that the calcs need to be 20A at 100 ft.
There is nothing wrong with running 3/4 but there is a lot of insistence that its actually going to help something which isn't accurate. Again another post,,,, which doesn't hurt anything but assumes that a bigger comp will need a bigger line. Its almost a compulsive reaction.

Go with the 3/4. You will be glad you did. The 1/2 would work fine until you decide you need a bigger compressor. I wish I would have gone bigger

I am curious as to why? Has it not worked out? Have you needed better performance? Did you add larger tools that need more air? What happened?

 

[sberry]

This is a little like saying,,, I have 100A service and 12 wire to 20A outlets but I will run 10 in case I upgrade the panel to 200.

 

[pbon]

No point in more than 1/2 with the present 10cfm at 90 compressor. I am not even sure you need more with the next size up compressor that does maybe 18 at 90. 3/4 wont hurt but I see no reason to go any bigger unless you have some industrial use planned for the future with massive compressors—and presume you would have mentioned that if it was the case.

 

[BD1]

I did all 3/4'' too. It's not that much more and worth it in safety and durability.
3/4'' has a little heavier wall and will take more abuse. As for the tees, have them looking up and then set over and drop down. This will provide drier air and the swing joints will correct and if the tees is leaning in or out.

IF you want a awesome system , look into copper PROPRESS fittings. It's great and will cost more. No solder or flux, a clean crimped joint. Depending where you buy, some suppliers will rent or loan you the tool for free.

https://www.viega.us/en/products/innovations/viega-propress.html

https://video.search.yahoo.com/yhs/...17309ab3c2eef5ae9d10666843b151fd&action=click

 

[bczygan]

Go with the 3/4. You will be glad you did. The 1/2 would work fine until you decide you need a bigger compressor. I wish I would have gone bigger

3/4 is not needed, even for a larger air compressor.

A 10HP compressor with 35CFM only has 6PSI loss at 150PSI and 9PSI at 100PSI. This is for 1/2" pipe.

For 3/4 pipe it is .969 and 1.45.

Bill

 

[sberry]

I see from another thread the guy above is adding a 3/4 impact which is a different issue than the size of the compressor. But, this has a quite a bit to do with the length of the circuit too. If he is adding the 3/4 gun to a 100 ft circuit the 3/4 pipe would help some, if he is adding it to a 25 ft circuit way less difference.
He is changing to a 1/2 hose also which will really help, its the big factor and as was mentioned by another earlier a little depends on the point of regulation too.

A 10HP compressor

Bill, the size of the comp is really irrelevant to some extent, its the tool demand. But you can see some rise in loss starting to factor as the demand escalates. This is loss before a hose is added. It might not matter at all if it is pre regulator.

 

[ford33]

I used 3/4" copper in my small 2 car garage. I don't really need the larger tube but the additional cost over 1/2" copper was not a significant increase in material cost and the extra flow volume may come in use someday.

Also, if available, use the type "L" rated copper tube. It is stronger than "M".

 

[dr_clyde]

Some of this boils down to small details. Slight increases in flow and capacity.

A home shop doesn't need big air lines. They just don't. 1/2" pipe is sufficient for a lot.

That said, some guys really want to future proof. Be prepared for ANY situation. Whether or not its practical IS NOT a factor. Its worth the extra money for us to not have to think about whether or not the air lines are big enough. They just are.

Labor is pretty constant between sizes, so all it boils down to material cost. If it only costs a couple hundred bucks more to do 1" vs 1/2", most guys will get the bigger.

FWIW, my 1800 sq.ft shop is plumbed with 1" black pipe mains and drops. I am never wanting for more air.

Other than a few extra dollars, there is NO downside to going bigger.

 

[sberry]

Other than more potential for leaks, possibly low velocity to clear condensate. The potential for some people not to get fittings tight enough in larger sizes.
I have 6000 ft shop, the long runs are 1/2 pipe, I also don't want for more air. Biggest gun I use is 3/4 and its a 2 stage system.

 

[dr_clyde]

Other than more potential for leaks, possibly low velocity to clear condensate. The potential for some people not to get fittings tight enough in larger sizes.
I have 6000 ft shop, the long runs are 1/2 pipe, I also don't want for more air. Biggest gun I use is 3/4 and its a 2 stage system.

Ehh, I would say the leak potential is more based on the skill of the plumber, I don't have any noticeable leaks in my system. It was plumbed and leak checked by some friends of mine who are pro plumbers. I will concede with more pipe diameter, there is more surface area for a leak to be, but if the joint is sealed properly, it shouldn't be a problem.

As for velocity, if the air is dried properly and the condensate condensate traps are located in the right place, that's fairly negligible.

The compressor has no effect on air piping. Air is air, whether its compressed by a HF pancake compressor or a Gardner Denver screw, the pipe doesn't know. However, a 1/2" system won't be able to flow the full output of a big screw, where it will be oversized for the pancake's output.


Having plumbed a few big industrial air systems now, I will agree that most home shops would be absolutely fine with 1/2" pipe. However, to say that there aren't situations that will benefit from bigger supply lines is not entirely correct. Sandblasting, large air sanders, and lots of other air hogs will only have an advantage.

I stand by the statement that there is no harm in going bigger if you are OK with spending the money.

At the end of the day, its all about diminishing returns. Most anything will work, but if that extra little bit is worth it to you, I don't see any harm in having it.

 

[signcrafter]

Being the internet I think sometimes some assumptions get made. Usually there is a reason someone will get a larger compressor, usually being that they need more CFM. So yes, a bigger compressor may be irrelevant but at the same time if you are getting a larger compressor usually it's because you are needing to run bigger tools.

So while 1/2" is plenty and probably will be plenty for most on here. And is plenty even with a bigger compressor until you get an air thirsty tool that needs to be fed and depending how far away from compressor it is. But at the same time when you can run 3/4" for very minimal cost over 1/2" then your shop is setup for pretty much anything you can put in it. Where if you run 1/2" and later add a bigger compressor and a high CFM tool then you have to start all over. Guess it all depends on what you see in your future.

For me it makes perfect sense to run 3/4" mains. I have a sandblaster that I would like to be able to use. Right now my compressor is only 10.5 CFM at 175 PSI, not sure what that is at 90 PSI. So it is way too small to run my blaster for more then a few minutes. So eventually I'd like to get a bigger compressor for using the blaster. Also would like to get a blast cabinet at sometime. I have a 3/4" impact. Have a few sanders that really are air hogs. So a bigger compressor is in the future plans for me since I could use it for some of the tools I have or plan to have.

Is 3/4" needed for running a bigger compressor with my tools? I don't know, and to be honest it isn't really worth it to me to figure out if it is or not. I will go with 3/4" and be set for pretty much anything I will ever need or do since cost is very very minimal. It just makes sense to me. Maybe 50 extra bucks for 3/4" system over 1/2" system in my case. Then I will be set and adding a bigger compressor or higher CFM tool isn't a concern. Now if I was to go with 1/2" because it's fine right now, then end up getting a high CFM tool and bigger compressor I have to start all over running 3/4" and all the 1/2" I previously installed is wasted money and time. To me this is an easy decision weather it's really needed or not. Kind of a better safe then sorry situation.

Does my logic apply for everyone, nope. It's just what makes sense to me.

 

[ez-duzit]

Larger piping has greater potential for cooling the compressed air.

 

[bczygan]

I see from another thread the guy above is adding a 3/4 impact which is a different issue than the size of the compressor. But, this has a quite a bit to do with the length of the circuit too. If he is adding the 3/4 gun to a 100 ft circuit the 3/4 pipe would help some, if he is adding it to a 25 ft circuit way less difference.
He is changing to a 1/2 hose also which will really help, its the big factor and as was mentioned by another earlier a little depends on the point of regulation too.
Bill, the size of the comp is really irrelevant to some extent, its the tool demand. But you can see some rise in loss starting to factor as the demand escalates. This is loss before a hose is added. It might not matter at all if it is pre regulator.

The calc. below IS for a 100' line. A 3/4" impact needs 9CFM average and 36CFM continuous duty. See attached chart for CFM needs and explanation of average and continuous CFM.

Ehh, I would say the leak potential is more based on the skill of the plumber, I don't have any noticeable leaks in my system. It was plumbed and leak checked by some friends of mine who are pro plumbers. I will concede with more pipe diameter, there is more surface area for a leak to be, but if the joint is sealed properly, it shouldn't be a problem.

As for velocity, if the air is dried properly and the condensate condensate traps are located in the right place, that's fairly negligible.

The compressor has to no effect on air piping. Air is air, whether its compressed by a HF pancake compressor or a Gardner Denver screw, the pipe doesn't know. However, a 1/2" system won't be able to flow the full output of a big screw, where it will be oversized for the pancake's output.


Having plumbed a few big industrial air systems now, I will agree that most home shops would be absolutely fine with 1/2" pipe. However, to say that there aren't situations that will benefit from bigger supply lines is not entirely correct. Sandblasting, large air sanders, and lots of other air hogs will only have an advantage.

I stand by the statement that there is no harm in going bigger if you are OK with spending the money.

At the end of the day, its all about diminishing returns. Most anything will work, but if that extra little bit is worth it to you, I don't see any harm in having it.

1/2" will handle up to a 10HP 35CFM compressor. If those things needed more CFM, then yes, you would need a bigger compressor and line.

3/4 is not needed, even for a larger air compressor.

A 10HP compressor with 35CFM only has 6PSI loss at 150PSI and 9PSI at 100PSI. This is for 1/2" pipe.

For 3/4 pipe it is .969 and 1.45.

Bill

I don't see a home shop using bigger than this. Maybe I am missing something. I thought it might be loss in the fittings, but 90 degree fittings only add up to 2' of equivalent length to a system. Even if there are 10 turns in the line, it only adds 20' to the calc. Maybe filters have more effect. And maybe rate of flow is the determining factor, I've read that systems should be designed for 20FPM flow to minimize turbulence.

Bill

 

[ez-duzit]

bc--why are you screaming at us?

 

[lis2323]

I have a 5 HP Atlas Copco 22 CFM and have never run into an air supply volume with 1/2 plumbed lines. A sandblast cabinet and a 3/4” impact are probably my biggest “hogs”.

IF I ever get around to setting up my Quincy rotary screw (for sandblasting with my Clemco pressure pot) I will most likely use 1” lines.

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[bczygan]

bc--why are you screaming at us?

Sorry!

 

[sberry]

It might probably could be slower than 20 fps, not sure what 20 cfm is thru 1/2. Yes, the avg is different and a totally useless number for most of us except that the real is normally 4 times that. Its not really a continuous number but actual number.
Good to look up as I guess most of the time, I tend to figure 3/4 guns at 35/40 and 1/2 at 20/25.
That 9 avg number is based on multiple units, a lot based on 100 when doing factory demand calcs. Like electric, say in a trailer park, only need to provide for 25% of them in a demand factor as they wont all be used at once. This was a point I was making in a thread some time earlier, guy was figuring he had to size pipe for everyone working at once and to match the comp size in a shop. It wasn't the true demand. It also doesn't mean squat if there is 5# drop on occasion if 2 or 3 guys happen to sand at a time. It doesn't cause a "waiting on air" situation.
Often the benefit of a larger comp is simply to reduce the cycle time so it isn't running all the time,,,, and for some bursts in demand. Bigger comp runs less hours, lasts longer.

 

[sberry]

That Atlas looks like a spiffy unit, I like that. The quinc screw will make a dandy blast unit, get big enough jet to run it steady.

 

[lis2323]

That Atlas looks like a spiffy unit, I like that. The quinc screw will make a dandy blast unit, get big enough jet to run it steady.

Bought the Atlas Copco for the farm brand new in the late 1970’s to run our carrot packaging line. Shop use only now.

Only had to replace the pressure cut off switch so far.




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