What size compressor

[RPBurris]

I am looking to replace my ancient small compressor that is good for filling up tires with something that can occasionally use a small grinder, 1/2" impact, and ratchet. Someday maybe a paint gun? I need to stick to a single phase unit and as with anything the budget is small. I found this one on line relatively close to home. The specs look good but I am not sure if it is big enough to do what i want. I can already fill up my tires so i dont need to have another compressor for that. specs below. Thanks!!

6hp Westward 20 gallon tank single stage 120Volt, 135PSI Max, 8.3cfm@40psi, 5.8cfm@90psi

[nate_g_2003]

I work at Grainger Industrial Supply, and those are decent, good for homeowner use.

What you want to look for is how much air the tools you will be using require. 5.8cfm @ 90psi isn't bad, but the paint gun and your impact may be starved a little. The higher the CFM @ 90psi you can get is better. You could paint with that compressor, but make sure you have a good filter reg on it, or the moisture and oil will ruin any painting you did. Your grinder, impact, and ratchet should do okay, will probably kick the compressor on a lot.

[Lee H]

Figure out which of your tools draw the most CFMs at xx pounds and buy a compressor that will supply at least that amount. If you don't know what your tools draw go onto a tool site and look for a representative sample. Stay away from the oil-less ones, and keep in mind the the bigger the tank the less cycling it will do.
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[RPBurris]

Thanks for the responses. I knew this would be the right place to get some info...

[ETsC10]

X2 on all the above though I think buy twice the
capacity of what you think you will need.

...ya never know when you will inherit an air pig that
you just have to have!

[Shane]

buy the most CFM @ 100 psi you can afford. Don't worry about he HP rating.

[PanelDeland]

Look at NT for specials.I paid $300 for a 30 gal 150 psi 6.8 cfm @90 psi uit.It was a "Cobalt"(Lowes house brand) that had been resold(maybe repair warranty or something) and rebadged for sale thru NT.That's about 35% off what the Lowes cost.

[72lb4x4]

"6hp Westward 20 gallon tank single stage 120Volt, 135PSI Max, 8.3cfm@40psi, 5.8cfm@90psi"

20 gallon is too small to do anything useful with.
6hp and 120V? Not likely at all.

746 Watts is 1HP
Power is measured in Watts
Power=Volts*Amps

From the above we get

(6hp*746W)/120V=37.3A

A normal house 120V appliance circuit is 20A so you'll never get 37A.

Add to that the fact that motors aren't that efficient and you'd be around 45A to get 6HP. I wouldn't buy anything with such a nonsense HP rating. What else are they lying about?

I'd be looking for a used made in the USA 60-80 gallon tank compressor from CL.

Once you buy the compressor, you need a regulator, filter(s), hard lines, etc. You can spend a lot on just this stuff.

The compressor and related stuff can easily be the most expensive thing in the garage. Get a good big compressor to start...

[Max1775]

If you want to get a serious compressor that you can grow with, I'd go with a 60+ gallon stationary that puts out at least 10 CFM @ 90 psi. Two stage is a plus due to higher pressure capacity gives longer time between cycles. You can find some good steals on Craigslist on occasion.
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[MGCarr]

Most compressor HP ratings are phoney as all get out. The proof of a compressor's capacity is in the CFM rating. 10+ CFM/min @ 90psi is a good goal to reach for. The bigger the receiver the better. 60 gallon tank means less compressor cycling and gives you some reserve for running some air hungry tools and sprayers.

I picked up the compressor below for $325 off from Craigs list, then spent an other $300 running the 230V circuit and plumbing it up.

It is well worth the effort to go with the 230v set up. The rating of 15amps on most motors that plug into a standard household plug just doesn't quite cut it.

A two stage air compressor is superior to a single stage unit in both capacity and efficiency. If you need much more than 10cfm@90psi you will need to look at 2 stage units, but be prepared to spend considerable more $$. Mine is a single stage pump. Note that a two cylinder compressor is not the same as a two stage compressor. A two cylinder pump has both cylinders in parallel and both cylinders take air from atmouspheric pressure to tank pressure. A two stage pump has a low pressure and a high pressure cylinder running in series. The low pressure cylinder discharges into the high pressure cylinder which discharges into the tank.

If the pressure switch settings on different compressors are close, I have seen guys run more than one compressor for stuff like sand or soda blasting but just run one when doing less intensive air tool work. Just tee in the air hose. Plug them into different outlets/circuits. The two cfm ratings will add up. Be careful with this! Don't miss-match pressure ratings, for instance, don't tie a 100psi compressor to one that puts out 130psi. The pressure switch settings and the tank pressure ratings need to be similar or relief valves may lift or worse, stuff can rupture.

A good compressor set up is really worth the money and effort. Bite the bullet and do it right the first time. You won't be sorry.

[wildearp]

One of the best compressors out there is a single phase Ingersoll Rand from their industrial line. 24+ cfm at any pressure up to 175psi with 100% duty cycle.

If you are pushing auto body tools and running a paint gun, a lesser compressor will leave you wanting. I run a 2 stage 80 gallon Devilbiss and it is barely enough for what I do. I spec'd the IR for a jobsite and I was immediately in lust. I used it for a couple years and loved it. I may just sell mine at some point to upgrade to this one.

Link:

http://www.aircompressorsdirect.com/...ssor/p738.html

The specs say 3 phase, but you can order it (or wire it) for single.

If you are doing a lot of soda blasting or sand blasting, at production levels, this is still not enough compressor. The guys that bought this compressor for me bought a pull behind compressor like they use for jack hammers to run their sand blaster.

I bought three compressors for my home shop before I had one that was 'big enough'. The devilbiss is barely big enough.

Consider one more thing, and that is the compressor name plate rating. If the cfm delivery rating is at 240VAC and you have only 208VAC, you will be downrated by 13%.

[Shane]

you can't "wire" a three phase motor to run on single phase. you can either change the motor, run an electronic phase converter, build a "pony motor" to generate the third leg or run it thru a variable frequency drive.

[mbgmike]

Originally Posted by Shane

you can't "wire" a three phase motor to run on single phase. you can either change the motor, run an electronic phase converter, build a "pony motor" to generate the third leg or run it thru a variable frequency drive.

Thats true. The housing on a three phase is too small to rebuild as a single with the same ratings. I have found after buying several industrial compressors it cheaper to go to graingers and replace the motor. They offer a quality compressor motor for around $600 for a 5hp motor. A lot less expensive then messing with converters. Thats what we do. I always buy used compressers at auction and you get a better deal on the 3 p cause know one wants to mess with them.
Most of the time you can sell the 3p motor and hot box (if it works) for about 1/2 half the cost of the new motor. Alot of guys turn the 3p into a homemade converter so you can recoop some $

I won't buy anything less then a 5 hp and at least a 2 stage 80 gallon tank and 20 cfm at 100psi even if you have to save up for it.
I have put together $4500 compressors for under $1500 buying at auctions and
replacing motors if you don't mind doing all the work. I bought a champion from the city of pearland tx for $300.00 during an upgrade of their shop for $300 and replaced the motor. $300+120 for hot shot service+$550 for new motor It was only 6 years old and worked great. Retail was over $4800 with the options it had.

[bcutt]

This is my Campbell Hausfeld 60 gal compressor. Got it at Tractor Suppy, I paid $399 for mine. Cant beat it for the price.

http://www.tractorsupply.com/tools/a...ressor-3310006

[mbgmike]

I wore out two of that brand It works but if you want to buy a tool for life it not there. If You are Young buy a good one and for the homeowner you will never have a problem again. I learned the hard way.

[RPBurris]

I have looked at the CH at Tractor Supply. I might just hold off on a purchase till i can get some 220 out to my garage. This has definetly helped so far.

[mbgmike]

Originally Posted by RPBurris

I have looked at the CH at Tractor Supply. I might just hold off on a purchase till i can get some 220 out to my garage. This has definetly helped so far.

Its not hard to install 220 if you have power there now. If I was close I would do it for you

[Shane]

don't bother with the Campbell Hausefield ... save up a few more $ and go with the Ingersol-Rand.