Compressed air pipe sizing

[ron in sc]

Is there a guide for what diameter of pipe to use with a system? Say you have a 5 hp compressor that puts out about 17.5 CFM @ 175 psi and your longest run will be around 100 ft. In that case what diameter pipe should one use. Compressor has 3/4" ball valve on tank.

I'm sure there is some complicated math forumula but I'm real bad with math.

 

[z28toz06]

Is there a guide for what diameter of pipe to use with a system? Say you have a 5 hp compressor that puts out about 17.5 CFM @ 175 psi and your longest run will be around 100 ft. In that case what diameter pipe should one use. Compressor has 3/4" ball valve on tank.

I'm sure there is some complicated math forumula but I'm real bad with math.

Air Line piping for dummies! The link at the bottom will show all you need to know.
Air Line Pipe Size
Figures in body of chart are pipe sizes on a 100 PSI air system to carry air at about a 1 PSI per 100 feet pressure loss. When measuring piping distances, to be conservative, count each pipe fitting as equal to 5 feet of pipe. At other than 100 PSI, flow capacity will be in inverse proportion to pressure (as based on PSIA (absolute) pressure levels and calculated by Boyle's Law).

SCFM Length of Run - Feet
Flow 25 50 75 100 150 200 300 500 1000
6 1/2 1/2 1/2 1/2 1/2 1/2 1/2 3/4 3/4
18 1/2 1/2 1/2 3/4 3/4 3/4 3/4 1 1
30 3/4 3/4 3/4 3/4 1 1 1 1-1/4 1-1/4
45 3/4 3/4 1 1 1 1 1-1/4 1-1/4 1-1/4
60 3/4 1 1 1 1-1/4 1-1/4 1-1/4 1-1/2 1-1/2
90 1 1 1-1/4 1-1/4 1-1/4 1-1/4 1-1/2 1-1/2 2
120 1 1-1/4 1-1/4 1-1/4 1-1/2 1-1/2 1-1/2 2 2
150 1-1/4 1-1/4 1-1/4 1-1/2 1-1/2 2 2 2 2-1/2
180 1-1/4 1-1/2 1-1/2 1-1/2 2 2 2 2-1/2 2-1/2
240 1-1/4 1-1/2 1-1/2 2 2 2 2-1/2 2-1/2 3
300 1-1/2 2 2 2 2 2-1/2 2-1/2 3 3
360 1-1/2 2 2 2 2-1/2 2-1/2 2-1/2 3 3
450 2 2 2 2-1/2 2-1/2 3 3 3 3-1/2
600 2 2-1/2 2-1/2 2-1/2 3 3 3 3-1/2 4
750 2 2-1/2 2-1/2 3 3 3 3-1/2 3-1/2 4

http://www.airheads.net/tech/index.html#

 

[toms73novass]

lets try this..

 

[ron in sc]

[

Air Line piping for dummies!

That's me.

So what is this inverse proportion stuff when other than 100 psi? My system is 175 psi.

 

[Charles (in GA)]

[

That's me.

So what is this inverse proportion stuff when other than 100 psi? My system is 175 psi.

Two trains of thought here. One is that you put the tank pressure, 145-175, out to the system, and then at each drop, regulate it down to what ever you need, most likely 100 psi or thereabouts.

Second way of thinking (and this is how I'm going) is to put a large, high capacity regulator and seperator/filter near the compressor, then drop the pressure to 100 psi or so and supply the system with the regulated air. With properly sized pipe you will have little to no pressure drop (as evidenced by the charts above), and you have only bought one regulator. Two stage units get the tank hot, then it cools, the water really condenses in a two stage's tank, and very little leaves the tank. I'm running a seperator and regulator right on the tank for now, with a hose from it. I'm yet to see the first drop of water out the hose.

I have a huge Wilkerson regulator, 1" pipe thread ports, something like 450CFM max flow. Bought it from Surplus Center for under $50. I'll use this when I do the hard plumbed system.

When you up the pressure you lose the flow, so you really need large pipe to compensate at higher pressures, another reason to keep the pressure down.

Charles

 

[bmwpower]

I guess the "regulator at the compressor" idea would only be good if you use one tool at a particular psi. If you paint, sand blast or do something else thata requires a different psi, then you'd have to have another regulator at that station.

Is it ok to have 2 regulators in the line of flow, ie. one at the tank for the whole system and then another one at a particular work station for sand blasting, say? Pressures can only be set downwards, correct?

 

[boiler7904]

Is it ok to have 2 regulators in the line of flow, ie. one at the tank for the whole system and then another one at a particular work station for sand blasting, say? Pressures can only be set downwards, correct?

It's ok to have 2 regulators in the line of flow but each added part is something else to eventually fail and have to be replaced. One of the engineers I'm working with now avoids inline regulators on air and gas piping whenever possible for this reason.

I would tend to agree that pressures can only be set downwards - what would increase the pressure?

 

[bmwpower]

It's ok to have 2 regulators in the line of flow but each added part is something else to eventually fail and have to be replaced. One of the engineers I'm working with now avoids inline regulators on air and gas piping whenever possible for this reason.

I would tend to agree that pressures can only be set downwards - what would increase the pressure?

I dunno. Don't blasters run at a higher psi?

 

[ZRX61]

Black pipe is so cheap you could run 3/4 just for the blasting cabinet & have a completely seperate system for everything else in the shop. Ideally you want 50ft of pipe (or more) between the compressor & the blasting cabinet to allow the air to cool & condense the moisture out. Then have a reg/sep on the cabinet to catch it.
You could even use the (very slightly) more expensive green pipe if you like Kawasaki's