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2nd December 2014, 12:30 AM #1.
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Cost of reticulated compressed air
One of my jobs for the new mens shed is to set up reticulated compressed air around the shed and thought some of you now or in the future might like to see some comparative costings for different systems.
The main workshop are is 14.5 x 7.5 m, the 45 cfm compressor is outside the shed in an enclosure and the specifications/costing are for a complete loop around the shed (44m of pipe) with 10 drop down access points around the walls. The drop downs were to be done with Flexible High Pressure plastic pipe.
The systems costed were
1) 20 mm Galv pipe. ($537)
Pipe is expensive (~$8/m), fittings are cheap, ($2/$3) but can be reused.
Installation is time consuming and retrofitting awkward.
Pipes will eventually rust
2) 19 mm copper pipe ($518)
Similar costs for pipe and fittings to Galv pipe although fittings not normally reusable - they are cheap away.
Installation is not as time consuming as Galv but retrofitting still awkward.
3) Flexible High Pressure plastic pipe & compression fittings (CF) ($326)
Pipe comes in a cheap (minimum length) 50 m roll but CFs are expensive
Installation and retrofitting are easy
Main problem with this is that expansion of pipe produces dips which stops water from draining properly
4) rigid High Pressure plastic pipe & CF ($575)
Pipe or hose is closer to Galv and Cu price and CF (same as for the flexible pipe) are expensive
Installation and retrofitting are easy and no problem with water draining properly.
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2nd December 2014 12:30 AM # ADSGoogle Adsense Advertisement
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2nd December 2014, 07:32 AM #2
Given the relatively large capacity of your compressor are you going to have large enough piping to adequately meet the flow requirements for your applications?
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2nd December 2014, 09:09 AM #3.
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2nd December 2014, 09:30 AM #4GOLD MEMBER
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I like the concept of multiple points in the shed, and it has me thinking.
Now I admit that I know nothing about compressor capacity, but would a compressor of 20 cfm be sufficient for an 'average' shed? Uses would have to include the use of spraying equipment etc.
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2nd December 2014, 09:44 AM #5
I friend of mine has one of those small 'Auto Cheap' compressors. You know the ones that are about $200 with extras. He uses that and has a couple of points available. It runs paint gun and sand blaster. What he has is a huge reserve tank like the size of a 1200mm high gas tank.
It takes a while to fill but if he is using it in bits and pieces as many shed workers would be he hardly ever empties it to the point that he has to wait for the compressor to build up.
I was thinking with my new cave (when it finally gets done) to have my old compressor set up as a reserve tank at one end and my main compressor at the other.
Thanks for the heads up on pricing & options, it is something I have been contemplating for some time.
Dave the turning cowboy
turning wood into art
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2nd December 2014, 10:09 AM #6
I'm planning a dual use point setup with a similar run length and though I can do it with the diameter you suggest I use a number of air-hungry tools like die-grinders, pneumatic hammers and a needle scaler and as I only want to install the system once I'm going to use 25mm piping.
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2nd December 2014, 10:52 AM #7.
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20CFM (as long as they are real CFM) is heaps.
Actually for a DIY even 10 REAL CFM is usually plenty
To work out the real CFM is not that difficult and you need to know the following
A) the volume of your tank in cubic ft (if you know it in litres, multiply the Litres by 0.0353)
B) The time it takes to recharge the tank in minutes.
C) the fractional pressure increase during the recharge. i.e. the PSI increase during the recharge divided by 14.5PSI. Lets say the pressure goes from 90 to 120 PSI so that's a gain of 30 PSI, now divided by 14.5 PSi so thats (120 - 90)/14.5 = 2
Now use this formula (A x C)/B
If the tank is 100L thats 3.53 Cubic ft, if it takes 1 minute to recharge from 90 to 120 PSI then
(A x C)/B - (3.53 x 2)/1 = ~7 CFM
Don't be surprised if your compressor fails miserably to meet the manufacturers specification
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2nd December 2014, 12:12 PM #8
I think CFM is relative to a PSI. So a manufacturer may say 10 CFM at 70 psi. 70 psi is much easier to generate than 110 psi.
My 18v makita air blower can generate significant cfm air flow compared to my compressor but almost 0 PSI
I am happy to stand corrected.
Your calculations Bob look something worth me keeping to see if my compressor is up to the use of certain tools when I finally get around to having and setting up my cave
Dave the turning cowboy
turning wood into art
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2nd December 2014, 05:36 PM #9Taking a break
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A filter/drier on the outlet of the compressor would eliminate any rust/drainage issues (not to mention just being good practise)
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2nd December 2014, 07:51 PM #10
5% loss at 120psi may be significant for some tools / applications.
What tools are you likely to be connecting to the air supply?
what is the flow demand of those tools?
a very very quick Google, suggests that one model of air sander needs >10 cfm to operate
I'm not sure that I'd trust a men's shed with plumbed air.
It will be all too easy to grab the air hose to clean up at the end of the dayregards from Alberta, Canada
ian
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2nd December 2014, 08:22 PM #11.
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We have no air powered tools at the moment and none are on our current wish list - that was why we originally targeted a 20cfm compressor
The most likely first thing we will buy that needs air is a plasma cutter.
I'm not sure that I'd trust a men's shed with plumbed air.
It will be all too easy to grab the air hose to clean up at the end of the day
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2nd December 2014, 09:30 PM #12
doing that will sort of make venting the dust collector outside pointless
regards from Alberta, Canada
ian
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2nd December 2014, 11:07 PM #13.
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2nd December 2014, 11:20 PM #14
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3rd December 2014, 07:50 AM #15
Which pipe solution did you end up going with??
Also with the copper pipe could it be sourced cheaper if you know someone in the trade ie a plumber?…..Live a Quiet Life & Work with your Hands
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