Air compressor for home garage

crankcall said:
Also remember pressure drops in the line, 90psi at the compressor on a 50ft hose is not 90psi anymore
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Well, it is still 90 PSI even at the end of a 1000 Foot hose...until you start to draw from it, then yes, the PSI can drop significantly. Hose length plays into it for sure, but hose size also plays a huge part. If you look at roadside service trucks for example (the ones that change big-rig tires anywhere, anytime) they tend to have a huge amount of hose to their compressor...simply because they may need to run their 1" drive impact guns potentially 80-100 feet away from their truck...but that hose is typically HUGE - 1" minimum, and I've bigger as well.

As for my own setup, I forgot to mention that I also bought an equally sized pig-tank at a yard sale for $10 a few years ago - for jobs where I know I'm going to consume a lot of air in a short period of time (impact gun, mainly), I setup the pig tank on a manifold at the compressor so that it basically doubles my tank capacity. Yes, it takes twice as long for the compressor to actually fill both tanks, and twice as long to recover them when I'm working it hard, but it gives me a lot more flexibility in the end...while still allowing me to keep the smaller compressor that is portable versus installing a much larger unit that could never leave my garage.
 
Special buy at Canadian Tire....219 bucks for 26 gallon compressor....



extra_large
Mastercraft 26-Gallon Oil-Free Compressor
Special Buy $219.99 or $9.17/month**
Valid December 02, 2016 - December 08, 2016
While quantities last.
Sorry, no rainchecks.
**Monthly price based on the sale price financed on a 24 month NO FEE, NO INTEREST equal payments plan. Applicable sales tax not included.


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Description

2-HP motor delivers 4.2 CFM @ 90 PSI. 199-8556-8

Product Features


  • Mastercraft 26-gallon oil-less compressor
  • 2 peak HP
  • Max PSI: 135
  • Delivers 5.2 CFM 40 PSI and 4.2 CFM 90 PSI
  • Weight: 117 lb.
  • 2HP motor, delivers 5.2 cfm 40 PSI and 4.2 cfm 90 PSI
  • Oil-free pump
  • Finish: Matte black

Product Specifications


  • WARRANTY: This product carries a 3 year repair only warranty redeemable at any Canadian Tire store.
 
PrivatePilot said:
Well, it is still 90 PSI even at the end of a 1000 Foot hose...until you start to draw from it, then yes, the PSI can drop significantly. Hose length plays into it for sure, but hose size also plays a huge part. If you look at roadside service trucks for example (the ones that ch
Click to expand...


dp = 7.57 q1.85 L 104 / (d5 p) ******* (1)
where
dp = pressure drop (kg/cm2)
q = air volume flow at atmospheric conditions (FAD) (m3/min)
L = length of pipe (m)
d = inside diameter of pipe (mm)
p = initial abs. pressure (kg/cm2)
1 kg/cm2 = 98068 Pa = 0.98 bar = 0.97 atmosphere = 736 mm Hg = 10000 mm H2O = 10 m H2O = 2050 psf = 14.2 psi = 29 in Hg = 394 in H2O = 32.8 ft H2O


There you go Mr. Science, its a pretty well known deal , which is why you see steel pipe running airlines around a shop and not rubber hose, and the regulator on the end of the steel pipe , not at the compressor.

visit the website engineeringtoolbox for formulas and lots of silly stats on airline pressure drops.
 
That's a whole lot of impressive numbers, but where is the flow rate in there? It's zero I hope, right?

Because at a zero flow rate (perhaps you missed that in my reply) pressure will eventually normalize across the entire length of any diameter hose/pipe given enough time. Only once you start consuming does pressure drop come into play, and yes, it can be hefty with small or long runs of plumbing.

As for the regulator being at the end of a run of pipe versus at the beginning that has everything to do with CFM – you can push more air/liquid through a pipe at a higher vs lower PSI. Lower the pressure at the latest possible moment for whatever desired PSI is needed. Similar logic is why electricity arrives in your neighborhood at tens or hundreds of thousands of volts before being steeped down to 110 at your receptacle, why your natural gas arrives at much higher PSI on the street but is stepped down at the regulator on the side of your house, etc...all without needing massive wires/pipes to accomplish a very high capacity in the end.
 
Last edited:
crankcall said:
your going to want to read www.engineeringtoolbox

q in the formula is airflow
Click to expand...

Yes, and I see exactly where you copied it from.

However, I'm not sure you understand the science behind what you're trying to prove. When there is ZERO air flow, there is no loss.

You can hookup a 1000 foot air line to a compressor with a tank and put another air tank at the other end. Start the compressor. Set it for 100PSI. Eventually, once the compressor achieves the 100PSI setpoint and everything equalizes...the tank at the other end will at at 100 PSI. The air line will be 100PSI along it's entire length. The tank at the compressor itself will be at 100PSI.

It will all equalize given enough time.

There's no "magic" restriction anywhere along an air hose that will cause part of the system to not reach equilibrium given sufficient time.

Again...during consumption this all changes..but that's not the argument you're putting forth.

Here's a simpler calculation on the Gates hose website. I entered 0.001 CFM (I had to enter SOMETHING, it won't accept zero) and as you can see, even across a 3820 foot hose (1 Kilometer!) of only 0.25" in size...zero drop.
pressuredrop.jpg


Now, mix in consumption and those figures change rapidly. Even 1CFM on the above equals a 13.5PSI drop..impressively little actually for 1 kilometer of hose actually, but at 2CFM you loose about 50% of your pressure.
 
I see that , I'm actually looking to prove nothing. You went looking for the part where static flow measures against movement. Nobody cares that the fuel consumption is reduced by 100% on an engine that's not running. But carry on.
 
GateKeeper said:
Special buy at Canadian Tire....219 bucks for 26 gallon compressor....



extra_large
Mastercraft 26-Gallon Oil-Free Compressor
Special Buy $219.99 or $9.17/month**
Valid December 02, 2016 - December 08, 2016
While quantities last.
Sorry, no rainchecks.
**Monthly price based on the sale price financed on a 24 month NO FEE, NO INTEREST equal payments plan. Applicable sales tax not included.


7 Reviews
More Details

Share:
Share on Facebook (opens a new window)
Share on Twitter (opens a new window)
Share on Google Plus (opens a new window)
Share on Pinterest (opens a new window)
Link

Description

2-HP motor delivers 4.2 CFM @ 90 PSI. 199-8556-8

Product Features


  • Mastercraft 26-gallon oil-less compressor
  • 2 peak HP
  • Max PSI: 135
  • Delivers 5.2 CFM 40 PSI and 4.2 CFM 90 PSI
  • Weight: 117 lb.
  • 2HP motor, delivers 5.2 cfm 40 PSI and 4.2 cfm 90 PSI
  • Oil-free pump
  • Finish: Matte black

Product Specifications


  • WARRANTY: This product carries a 3 year repair only warranty redeemable at any Canadian Tire store.
Click to expand...
Ok, why is that so cheap?

Sent from my SM-G900W8 using Tapatalk
 
kellen said:
Ok, why is that so cheap?
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Oilless typically means cheap, but (based on my experience) loud and not terribly longevity oriented. It's basically a cheap compressor on top of an oversized tank.

I'd bet that the duty cycle is something like 25% or less.

Still, not bad for a hobbyist if you can stand the noise, but oil drive compressors are so much quieter and will certainly last longer under anything more than light use/abuse.
 
And it s a repair only warranty so if anything goes, then you have to be without a compressor until it gets fixed. Some recurring complaints about it blowing breakers and failing after limited use. I like the matte black though.
 
not sure if it's been mentioned, but a larger diameter hose makes a big difference too......for painting, a 1/4" hose and fittings doesn't cut it , so just about everything I use has 3/8" fittings and hose for higher volume .... the big paint guns require a lot of air .... my compressor is only a 30 gallon oil lubricated unit , and it runs a lot while painting with the bigger paint gun .... I also have a small compressor (2 gallon ) that is much more portable , but it's oil free, and it makes a lot of racket and runs a lot .... fine for air stapling , filling bicycle tires etc , but that's about it ...... I sometimes wish I'd gone with at least a 60 gallon for my garage and paint work , but the 30 gallon unit is on wheels , is upright , and doesn't take up a lot of room ...... for paint work , you also need an air dryer unit , and lots of good filtration , before it goes to the paint guns .... just my .02 , Cheers , Les
 
Mine is very noisy (blue Campbell Hausfeld) ... any reasonably quiet ones on the market?
 
shanekingsley said:
That seems like a very nice unit. A little spendy, but worth it.
Click to expand...


Spend the extra money. Don't bother with that Canadian Tire one. It's a sub-par compressor attached to a large tank. The CFM at 90 psi is quite poor.

Look up various air tools and what CFM they require. Impact wrenches need a lot of air.
 
Anyone upgrading and have a small one they want to sell? Looking at a 2G one from CTC. Just need to fill tires and use as an air gun.
 
the small ones aren't a lot of use with an air gun (see post#36) , you get an initial big puff of air at 90psi? which promptly drops way off and then you are waiting for the tank to refill and come up to pressure. A small compressor is fine for filling tires, watch the CTC flyers for an electric impact on sale.
 
Not using for painting or anything. Just air blasts for cleaning out stuff like the inside of PCs and other dust things.
 
I completely agree. I bought a small CT air compressor (dual tank) in hopes to use my air impact gun. It doesn't work at all so I picked up the electric impact from CT (or Princess auto, can't remember) on sale. Super happy with the power of the electric. The compressor is good for filling tires and other small jobs.
 
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