sberry
Banned
Its about the perfect size for body paint.
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Another Shop air piping question....
- Thread starter rjprice
- Start date
sberry
Banned
That is probably about the break but its 10% that might not matter to get the work done but the real culprit is the ho0se past that. Its a real good case for 2 stage. If you are running it thru a reg it is less loss because its 150#. This also assumes the longest run at the highest load, really irrelevant for pumping an auto tire or running common tools. Its at the longest distance.
Our fire dept has a couple reels, someone plumbed to them with 3/8 brake tubing, it works, really 1/4 id for 50 ft but blows tires up. They don't run tools.
Its obviously undersized and would add insult to the system. However, in a common garage could use 50 ft 3/8 hose off the tank to a reg you have at 120 and you cant tell,,,, 3/8 or 3/4 on the main. If you go to 1/2 on the main never tell, no way no how.
There is a huge difference between 25/50 and 100 ft especially as loads go up. But I have 100 ft 1/2 steel I use 3/4 gun on no problem. I don't do it every day. Its well adequate, if I was plumbing a truck shop and was constant would have 3/4. But a couple points loss a couple times a year isn't squat, most the other loads 1/2 of that max. All regulated secondary.
Our fire dept has a couple reels, someone plumbed to them with 3/8 brake tubing, it works, really 1/4 id for 50 ft but blows tires up. They don't run tools.
Its obviously undersized and would add insult to the system. However, in a common garage could use 50 ft 3/8 hose off the tank to a reg you have at 120 and you cant tell,,,, 3/8 or 3/4 on the main. If you go to 1/2 on the main never tell, no way no how.
There is a huge difference between 25/50 and 100 ft especially as loads go up. But I have 100 ft 1/2 steel I use 3/4 gun on no problem. I don't do it every day. Its well adequate, if I was plumbing a truck shop and was constant would have 3/4. But a couple points loss a couple times a year isn't squat, most the other loads 1/2 of that max. All regulated secondary.
sberry
Banned
Its often thought that branch and T was for simultaneous loads and they are to some extent. But no difference in home run with 1/2 and 2 loads on branch and t with 3/4. Where the 3/4 outperforms it some is single load on long circuits.
I agree its even easier to overkill and not ride a line and it doesn't even cost much more. But, its misleading that most need it and will have some gain or that the other is inadequate. Yes, there is some loss on every transmission, a cord to run a saw but,,,, does the user care and how long would it actually pay and at what extra work for it all. Is it insufficient or inadequate on a 12/20 circuit to run a circ saw once in a while at 100+ ft , 5 or even 10% doesn't mean anything to the end user. Same for welder. Same for some other air tools.
Be totally different if the 1/2 pipe was actually inadequate and it didn't work.
I agree its even easier to overkill and not ride a line and it doesn't even cost much more. But, its misleading that most need it and will have some gain or that the other is inadequate. Yes, there is some loss on every transmission, a cord to run a saw but,,,, does the user care and how long would it actually pay and at what extra work for it all. Is it insufficient or inadequate on a 12/20 circuit to run a circ saw once in a while at 100+ ft , 5 or even 10% doesn't mean anything to the end user. Same for welder. Same for some other air tools.
Be totally different if the 1/2 pipe was actually inadequate and it didn't work.
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bczygan
Well-known member
losing 10% of your PSI to flow resistance at 100PSI is not a big deal? seems like an argument FOR bigger pipe. not like it's mountains of gold to move from 1/2" to 3/4" pipe if you haven't started yet.
Of course, I wouldn't run anything but a 2 stage compressor. And at 150PSI, the loss would be 6PSI, which is just 4%.
And at 175PSI it is only 5.15PSI loss. And remember this is for a 10HP 35CFM compressor on a 100' 1/2" line.
Lets go back to the typical 5HP 2 stage machine most of us run. At 17CFM with a 100' line of 1/2" copper the numbers are:
100PSI 2.37PSI drop
150PSI 1.58PSI drop
175PSI 1.35PSI drop
Even a 7 1/2HP 2 stage machine at 24CFM, with a 100' line of 1/2" copper, the numbers are:
100PSI 3.31PSI drop
150PSI 2.99PSI drop
175PSI 2.56PSI drop
Bill
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Engineer61
Well-known member
In ALL air systems your choke point is always going to be the quick disconnect, your major pressure drop is going to be in your 1/4" air hose. If you have something like a big media blasting gun that wants tons of flow you are better off doing away with the quick disconnect than you are going from 1/2" to 1" main line piping. For impact guns that want lots of pressure and flow or paint sprayers that want flow go from a 1/4" hose to 3/8" or even 1/2" hose, the new hybrid rubber hoses are much lighter than the old Goodyear rubber hoses so you can go up a hose size without having a lot of weight to haul around behind you.
rayra
Well-known member
People talking about 1/2" threaded fittings on their compressors seem to be disregarding that the QD ****** has a hole about 1/4" in dia. So any piping larger than that is no restriction on your protracted air flow. And 3/4" does little more than give you git more pressurized air before your tank blows down, but it doesn't help your volume much, because of that 1/4" restriction.
ez-duzit
Well-known member
...the QD ****** has a hole about 1/4" in dia. So any piping larger than that is no restriction on your protracted air flow...
Simply untrue.
sberry
Banned
I agree, not simply true. The hose is the greedy culprit in most apps that matter, the main one being heavy impact. The rest of the stuff doesn't matter much to this crowd.
BruceMc
Well-known member
It might probably could be slower than 20 fps, not sure what 20 cfm is thru 1/2.
Most threads like this, it seems people are usually overestimating the actual volume of pipe, and from there underestimating how quickly air moves from one end to the other.
At 1/2", iron pipe is only about 0.0021 cu ft / ft, or 0.21 cu ft over a 100' length. If you're moving 20 cfm through it, then it has to refill 95x each minute (20/0.21). IOW, that's 60 seconds / 95 fills, or around 0.63 seconds for a molecule of air to enter one end and exit the other in a 100' length of pipe. One consequence - in a typical hobby garage with much shorter runs, you can see how there's probably not a whole lot of heat getting stripped off in the couple of 10ths of a second that the air is in the pipe.
https://www.engineeringtoolbox.com/ansi-steel-pipes-d_305.html
sberry
Banned
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
It is true that 1/2 compared to 3/4 makes very little difference compared to a small connector and it would help more the longer the pipe was. These would be extreme though and not apply so much at these distances and use , that would be correct. Most all the loss worries so much about is in the hose though.People talking about 1/2" threaded fittings on their compressors seem to be disregarding that the QD ****** has a hole about 1/4" in dia. So any piping larger than that is no restriction on your protracted air flow. And 3/4" does little more than give you git more pressurized air before your tank blows down, but it doesn't help your volume much, because of that 1/4" restriction.
sberry
Banned
The tool you are using is the real restriction. The QD adds a little but even a cheap automotive is rated 35 or so, tools use 15/25,,, 25 for heavy impact, 2/3 the fitting rating, not causing a terrible loss. 3/8 hose at 25 cfm north of 2/3 # a foot, maybe closer to a # depending on hose condition. When there is 35# loss thru the hose 3/5 thru a connector doesnt mean a lot.
sberry
Banned
It only means something to the user on specific heaviest of tools, sanding, sandblast the losses are negligable, don't effect the operator. If the tool can't get enough air a little better hose will only make it worse, let's the comp dump it faster is all and only way to make it run longer is add restriction. May provide some choke effect and reduce waste.
It only means something to the user on specific heaviest of tools, sanding, sandblast the losses are negligable, don't effect the operator. If the tool can't get enough air a little better hose will only make it worse, let's the comp dump it faster is all and only way to make it run longer is add restriction. May provide some choke effect and reduce waste.
^^^ THIS^^^. I agree. Akin to “ Hurry up and wait”
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the only place the restriction should be (ideally) is at the end of the line. not the piping, not the hose. a small compressor with an adequately sized tank would be no different for intermittent tool use to "most" users than a large compressor with the same size (60/80gal) tank.
even looking at those numbers might make sense if you didn't have a tank... isn't the whole point of the tank to supply more air than the compressor can?
Of course, I wouldn't run anything but a 2 stage compressor. And at 150PSI, the loss would be 6PSI, which is just 4%.
And at 175PSI it is only 5.15PSI loss. And remember this is for a 10HP 35CFM compressor on a 100' 1/2" line.
Lets go back to the typical 5HP 2 stage machine most of us run. At 17CFM with a 100' line of 1/2" copper the numbers are:
100PSI 2.37PSI drop
150PSI 1.58PSI drop
175PSI 1.35PSI drop
Even a 7 1/2HP 2 stage machine at 24CFM, with a 100' line of 1/2" copper, the numbers are:
100PSI 3.31PSI drop
150PSI 2.99PSI drop
175PSI 2.56PSI drop
Bill
even looking at those numbers might make sense if you didn't have a tank... isn't the whole point of the tank to supply more air than the compressor can?
finn
Well-known member
No. With a given pump and a given demand, all a larger tank does is reduce the number of compressor start ups for a given task.
Larger tanks let you do more work between the high pressure and low pressure cutoff set points because there is more potential (stored) energy in a larger tank.
The cfm of the pump, with a properly sized motor, ultimately defines how much air can be supplied.
This is an enjoyable thread. Typical GJ overkill, rather than engineered solution.
Larger tanks let you do more work between the high pressure and low pressure cutoff set points because there is more potential (stored) energy in a larger tank.
The cfm of the pump, with a properly sized motor, ultimately defines how much air can be supplied.
This is an enjoyable thread. Typical GJ overkill, rather than engineered solution.
BruceMc
Well-known member
Larger piping has greater potential for cooling the compressed air.
While it's true that the air will move slower in a larger pipe, that's offset by the reduced ratio of surface area to unit volume. The bigger the pipe, the less efficient it will be for cooling.
sberry
Banned
Yes it is . You would be correct that there is often higher demand than the pump can supply. That is why I mention earlier, not the size of the comp but the tool demand that determines load.the only place the restriction should be (ideally) is at the end of the line. not the piping, not the hose. a small compressor with an adequately sized tank would be no different for intermittent tool use to "most" users than a large compressor with the same size (60/80gal) tank.
even looking at those numbers might make sense if you didn't have a tank... isn't the whole point of the tank to supply more air than the compressor can?
Finn statement applies to continious load but there are lots of situations that use air faster than it can be made.
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