Thread: Air Tools & Airline pressure drop

When I get worried about that sort of thing(is worried the right word? lol) I have a reg set up like your pressure gauge, which lets me run tank pressure in the line. For a die grinder I doubt you'd want the reg hanging off the end, so if you want to get excited, make up a belt clip* and a 1m line to go from the reg to the tool.
But then I dont think my compressor kicks in until 80psi anyway.

Stuart

*or other suitable nearby location.

Pressure drop is also strongly dependent on flow rates so to make a proper comparisons between the two lengths and hoses you need to attach a volume or mass flow meter

e.g. 20 PSI drop for a 15m 10 mm dam plastic hose suggests a flow rate of about 12CFM
The effect is strongly non-linear
e.g. If 6CFM is being used the Pdrop will only be ~6psi

Pressure drops are proportional to the fourth Power of the radius of the pipe being used so going from 10 mm to 12.5 mm diameter pipe makes a dramatic difference.
eg 12 CFM though a 15m x 12.5 mm pipe will lose PSI.

6mm hose is a complete dog for compressed air lines.
A 50 PSI drop in the second case suggests only a flow rate of 6 CFM is comimg out the end of that setup

BTW these can all be calculated using http://www.pressure-drop.com/Online-...tor/index.html

Without worrying where to set the regulator, as screwing it in/out all day would give me the pits, plus possibly wear out the regulator screw. I'd first work out how far from the compressor will my work area be, if it is 5 metres, check your pressure drop, if it is too much I'd use a bigger hose. At 10 metres, I'd run something like 1/2" hose or put in some pipe work with a receiver tank and run the regulator with a short hose from that.
I'm led to believe, that putting more pressure through the hose reduces quantity, due to friction losses.
I could be wrong, my partner, always say I am.
Kryn

What I would be doing is running 3/4 Steel pipe around the workshop so that I only needed 3 or 4 metres of hose for the job.

Roger

Originally Posted by rogerbaker

What I would be doing is running 3/4 Steel pipe around the workshop so that I only needed 3 or 4 metres of hose for the job.

Roger

There's no need to use 3/4" pipe unless you need flow rates of 30+ CFM.
I have compressed air reticulated to all 4 walls of my shed so the longest run of 1/2" pipe in my shed is 8 m
If I use 12 cfm the pressure drop is a whopping 3 psi.

Thanks for all the replies.

Bob, very interesting. I'll check out the link you gave.

Roger,
As funds allow I will be putting a 20mm or 25mm pipe around the garage and put the regulator on the end of that. I plan to have maybe a 5m or so 10mm ID hose to tools.

I use the 6mm coil hose for the blow gun only.

R
J


Thx
Jon

"As funds allow I will be putting a 20mm or 25mm pipe around the garage and put the regulator on the end of that. I plan to have maybe a 5m or so 10mm ID hose to tools."

Hi Jon
When you do that make sure you put a Bleed valve on the bottom of any vertical runs. It is amazing how much condensation you can get especially if you are spray painting.

Roger

This might help.
This is for smooth plastic pipe 10m long with a pressure of 145psi in the tank - when the pressure in the tanks is lower the pressure drop will be less.
The different coulours are for different diameter pipe
Only one point is shown for 6 mm pipe because it cannot support flows of 10 CFM and above

As funds allow I will be putting a 20mm or 25mm pipe around the garage and put the regulator on the end of that. I plan to have maybe a 5m or so 10mm ID hose to tools

I would encourage you to consider not putting steel pipe around the garage as the internal corrosion and hence rusty pieces ending up in the air stream system can be prevented by using copper or plastic air line. The galv pipe these days doesn't seem to be as good as the old stuff either.

in the interests of ensuring/obtaining best flow rates BIGGER IS ALWAYS BETTER

Originally Posted by BobL

This might help.
This is for smooth plastic pipe 10m long with a pressure of 145psi in the tank.
The different coulours are for different diameter pipe
Only one point is shown for 6 mm pipe because it cannot support flows of 10 CFM and above

Thanks Bob. This is one of those cases where a picture really does paint a thousand words! Just goes to demonstrate the benefits that can be gained by simply upsizing even a couple of mm in diameter.

R
J

Recently ran air line around my workshop, after searching the forum and finding this thread- https://www.woodworkforums.com/f65/quick-connect-air-couplings-air-pipe-150421 ( thanks Phil ! ) I decided to use 20mm blue stripe irrigation line and philmac fittings.
Went to the local irrigation supplier and told him what I was thinking of using it for and he said most of the local tyre businesses use it for air.....
Main line slopes down gradually with drain at end- so far no moisture has collected but I do have a refrigerated dryer fitted just after the air compressor (bought second hand off ebay) Just plug in a small regulator to what ever outlet I'm using.
The last picture is of an inline digital air regulator, really handy, mostly use just before the spray gun....


Daniel



IMG_1840.jpgIMG_1839.jpgIMG_1838.jpgIMG_1841.jpg

I've been investigating installation of air lines for our Men's Shed.
One thing I have learned is that the tap off points from the trunk line should initially go upwards.
The other thing is to slope the trunk lines and put a tap on the end f the slope.
This will further minimise water transfer into hoses.

Thumbs up for the blue stripe pipe and Philmac fittings. I just did the same thing in my workshop. I ran 50m of 25mm poly with lots of droppers around the workshop. It was pretty straight forward to do. Lots of compatible brass fittings that suit as well. I have a spray booth right at the end of the line and I still get a little mist in the pipes when I blow off the water trap. Every take off needs a water trap...well up here you do.