Hi Folks!
I live in southeast Arizona, 20 miles west of Tombstone.
I've searched the internet for a good air compressor for some time now. I define good as minimum of 7 HP, 2-stage, single phase, large tank, and not oil-free or the cheap blue ones for sale everywhere. Sure I expect to spend a few bucks for a good unit, but that is ok, it's worth it! Most compressors on E-bay are from the new england or florida area or are 3 phase, and a roto-phaser to change my single phase to 3 phase is about $1200.

What have you done or seen done in shops for good compressors?

Steve

 

Seems to me Home Depot sells Ingersol Rand compressors . The one I saw was a 60 or 80 Gal tank , 2 stage , oil & set up to use 220V .

 

[updated:LAST EDITED ON 17-Mar-02 AT 02:33 PM (EST)]Just want to put in one word of advice. Make sure you don't get one with aluminum heads. Get it with the cast heads. They might run a bit hotter but will last about five times as long. I don't know if you can get this brand where you live but in Michigan I used the "Sailor-Buel" brand. Not positive of the spelling on that brand name but it was something like that. I hade good luck with these when I used them in my heavy equipment repair shop.

Just found a link for you.....http://www.saylor-beall.com/home.html

Good luck.

 

I have a snap on tools compressor ive had for about 12 years 7 horse 80 gal 24 cfm cast iron v twin. Still works great and getting service parts a phone call away. A little pricey but sometimes you can get them on promotion or sale. Hope this helps. chuck

 

Checkout autobodystore.com, they sell good compressors with free shipping.

 

Sams Club.
Coleman Powermate BlackMAX
80 gal, cast iron cylinders, dual stage, 7HP, 220v
$699

 

Rol-Air makes a very good unit. Besides they are made just down the road from me. They have every type from construction site right to industrial. I am not sure if they have a web site. They are located in HustisFORD, Wisconsin.

 

CRAFTSMAN ,in my opinion has the best compreesor out. only because most go up to 130#. CRAFTSMAN goes up to 150# & runs on 110 elec. whih is convenient. big tires to roll around.& 1 person can lift it.

 

I went through this 2 years ago. I wanted an industrial compressor, not one of those home depot specials. What I did was go around to the different air compressor shops and talked with them. I learned what to look for in a good compressor and what to stay away from. I was almost ready to buy a Champion when I found this Quincy. It was HUGE, 20 horse pump, 15 horse Lincoln 3 phase motor, 120 gal tank. But I like you didn't think I could use it being 3 phase. Just on a chance I went back to the Quincy dealer and told them what I had access to and could they help figure out if I could use it. What we found out is that I could replace the 15 hrse mtr with a 7.5 single phase, and underspin the compressor to 405 rpm. I was even able to use the same mag starter just by dropping on leg in it. Now I have a compressor that puts out 35 cfm and keeps up with as many air tools or sand blasters we throw at it. Also at 405 rpm it will last forever.

compressor $1000.00
7.5 mtr $ 300.00
misc sheaves and belts $ 70.00

Total $1370.00
Cheaper than any lower quality compressor that will have to be overhauled in 3 years.

Just my two cents

Bushman

 

I would have to agree with Bushman. I did this 4 years ago and it was either a Quincy or Curtis. I chose a Curtis and would only have those two. Mine is a 80 gal 2phase 5.5 horse. Mine was price within 100 bucks of Bushmans. I paid 1400 for mine delivered to my home. Plus, most of the shops in my area have either a Quincy or Curtis.

I run alot of air tools in my garage so I didn't want something that I'd be replacing parts on in a couple years. Mine is 100% cast-iron. No aluminum for me!

The only suggestion I would make to you is make sure to ask what "Duty Cycle" the motor rated at!!! If you run your compressor alot (as I do) you might want to speed the money on a on a motor with a 70% duty cycle or more. If I had to do it all over again I would have gotten the 7.5 horse with a 80 to 100% duty cycle.

Duty cycle, (if I can remember), is how long the motor can run continiously in 1 hour. So, if you have a 50% duty cycle motor, technically it's only rated to run a half hour continiously. This might sound overkill but, I believe in overkill on a piece shop equipment like this.

I'm very pleased with my compressor and should get many decades of service from it. Remember, sometimes spending a little more now will save on a headache later. I'm sure those who bought those hardware store brands are getting good service from them but I was looking for something a lot better.

My .02¢

 

[updated:LAST EDITED ON 24-Mar-02 AT 10:09 PM (EST)]The Saylor-Beall is an excellent compressor.
I recently purchased one at an auction (gas station).

Most gas stations in my area use them (lower Michigan)
The one i have supplies plenty of air for all my sand blasting needs.
Sailor-Beall is located in St. Johns, Michigan

My son-in-law has a Sears with the motor attached directly to the pump. It seems to me to be extreamly loud.
Compressors with belt drive are not as noisy.

 

Some notes on "Retail" Horsepower designations versus "Actual" Horsepower and some helpful compressor calculations.

Some of the compressors available through retail outlets seem to have inflated HP ratings based on "instantaneous" torque multiplied by RPM which has nothing to do with ACTUAL horsepower. You will notice the motors involved usually have "special" or "SPL" when it comes to ratings on their nameplate. Our government and the weights and measures people have done nothing to protect the general public from this fraud. Check the tables below to find the electrical requirements to produce ACTUAL horsepower.

Some information that may help you specify or evaluate any compressor is detailed below.

In order to power air tools at their rated SCFM you can use the following formula to find the estimated ACTUAL horsepower required:

SCFM x HPF x 1.1 = HP

HPF (Horse Power Factor)
at tool rated pressure:
-----------------------
psi......HPF.......HPF
........1-stage...2-stage
-------------------------
40......0.107......----
60......0.136......0.128
70......0.148......0.138
90......0.170......0.156
100.....0.179......0.164
120.....0.196......0.178

1.1 is a factor used for figuring losses in the system.

Using a single stage compressor:
eg. 6 scfm @ 60 psi = 6 x .136 x 1.1 = .9 HP

Horsepower is also wasted by reducing the pressure through a regulator. This wasted power can be estimated by using the following formula:

RIP= Regulator Inlet Pressure
ROP= Regulator Outlet Pressure
4 SCFM = Tool consuption

[ (HPF@RIP) - (HPF@ROP) ] x SCFM = HP waste

eg. RIP= 100; ROP= 70; [ .179 - .148 ] x 4 = .124 HP

Above tables and formula's from:
Fluid Power Data Book, Womack Educational Publications.

Compressors also have a "duty rating" involved. The duty cycle is based on the percentage of time the motor is on while in use. The aluminum case or head compressors will warp or creep under the heat load of continuous operation. This creep will cause either internal or external leaks which decrease efficiency. Decreasing efficiency leads to longer run times and more damage. The electric motor itself has a temperature rise and a service factor as well as a duty cycle. The "special" motors do not specify these factors but you can guess what they might be... Service factor-.8; duty cycle- intermittant.

Actual continuous duty motors have fairly well established current draw versus voltage and HP ratings. The values below also have a "fudge factor" built in for line-voltage variations. There is no "free lunch" when it comes to horsepower.

See the following table for some generic values:

Single Phase Alternating Current Motors
Full Load Current in Amperes:
-----------------------------
HP-------115V--------230V
-----------------------------
1----------16----------8
1.5-------20----------10
2----------24----------12
3----------34----------17
5----------56----------28
7.5-------80----------40
10--------100---------50

The above values are from the National Electric Code and reflect their use in calculating branch circuit requirements. Also notice 115V values are twice the 230V values.

The following values are taken from the catalog of a major manufacturer of high efficiency industrial motors for compressors. They will more closely resemble the values you should see on motors on high quality compressor units.

Single Phase Alternating Current Motors
Full Load Current in Amperes:
----------------
HP-------230V
----------------
1----------8
1.5-------10
2----------12
3----------16
5----------21
7.5-------33
10--------44

You can see that efficiencies increase as motor size/HP increases.

To make things more confusing some retail manufacturers seem to "calculate" their SCFM ratings based on displacement and rpm. Commercial manufacturers actually test their units or use tables supplied by the pump manufacturer based on testing.

Do not buy the maintenance free oilless type compressors. They are
not only horrendously noisy they wear out VERY quickly. They are made of aluminum with the motor directly coupled to the compressor and are usually good for just a few hundred hours of operation (if you are lucky).


I hope you find this information useful and enlightening!



over!

 

[updated:LAST EDITED ON 08-Apr-02 AT 01:07 AM (EST)]I have a 220v 33gal 6hp Craftsman oilless and a 5.5hp 20gal and like them both. They sound like crap, but the 6hp has been in my garage for 8 years and I haven't changed the filter. (I've checked it)

The only reason I got the smaller one is to take places for repairs. It's an upright and if I could only have one it'd be it. Even though the other is more powerful.


You can get GREAT deals on these if you watch for them. The big one was $250 and the small one was $250 with an air ratchet and accesories.

 

I too own a 6hp 33 gal oiless Craftsman..Noisy but works well!
Also own a 1972 3hp 20 gal Craftsman(actually sears green) and
its old oiled filled, cast iron and nothing will kill it!!!
Now if i only had a gas powered one for the junkyard hunts!

 

I also have the Craftsman 6hp 33gal unit.Its great runs everything no problems.9 years running