Welcome! Please use the navigational links to explore our website.
PartsASAP LogoCompany Logo (800) 853-2651

Shop Now

   Allis Chalmers Case Farmall IH Ford 8N,9N,2N Ford
   Ferguson John Deere Massey Ferguson Minn. Moline Oliver

Attention Forum Users: On the 28th of December 2023 at 9:00am Central Time, we will be taking the forums down for maintenance while we prepare the new forums for your use. Please click here for more information.

Tool Talk Discussion Forum

Air compressor help

Welcome Guest, Log in or Register
Author 
jdjack

01-12-2008 15:22:04




Report to Moderator

I am looking at buying a air compressor.
They all show different specs.
These are all upright, 80 gallons, 230 volts,
twin,cast iron pumps.
15.6 scfm @100psi 6hp $800.00
25.0 scfm @100psi 7.5hp $1399.99
16.9 cfm 175psi $1400.00

What is the difference betweeen scfm and cfm?

I have alot of air tools. impacts, air hammer DA sander small sand blaster. Want to get one that will keep up. I will not make a living with this compressor, just working on my cars and tractors.

[Log in to Reply]   [No Email]
JoeK(WI)

01-13-2008 08:23:40




Report to Moderator
 Re: Air compressor help in reply to jdjack, 01-12-2008 15:22:04  
Make a list of your tools.Each has a recommended requirement/consumption rate such as (9.0cfm@90psi).In almost all cases running a higher unregulated pressure in PSI serves no purpose and increases wear on tool so a good inline regulator is important.Without regulation running the tool at"full flow" 125(single stage)or 175(dual stage)is wasting air.(Think of it as air mileage).Unused air going thru the tool that is doing no work is wasted,and tank will empty quicker decreasing performance.This being said, buying a compressor that will provide slightly more air than your"hungriest" tool and of reputable quality is generally satisfactory for hobbyist/homeowner use.Outsized compressors cost more to buy,run,get accesories for etc.In general for the duties you stated,a 5 to 7.5hp,60-80gal tank,single stage compressor delivering in neighborhood of 11-15cfm@90 thru 3/8" hose via regulator should do you fine for less money than models you listed.
Opinions based on experiences.

[Log in to Reply]  [No Email]
TimV

01-13-2008 06:40:01




Report to Moderator
 Re: Air compressor help in reply to jdjack, 01-12-2008 15:22:04  
jdjack: a few thoughts here--first, you may want to check this site's archives, as this question is one of the most frequently asked ones on this site--there will be a wealth of information on this topic there. Scfm is standard cubic feet per minute--in other words, cfm at a standard temperature and pressure. The reason for this (as the name implies) is to give a standard so you're comparing apples to apples when shopping units. CFM decreases as pressure rises, as the compressor must fight against the air that's already compressed in order to produce more air. Therefore, without scfm as a reference, one manufacturer could claim a higher cfm number for their machine because they were using a lower working pressure as a reference. Regardless of this, you're probably most interested in the cfm the compressor will produce at around 90-100 PSI, as this is where most air tools operate. A note of caution--air compressors manufacturers are notorious for overrating their machines, both in terms of motor horsepower and in terms of cfm output. This has been the basis of several lawsuits in recent years, and so some labels are beginning to reflect numbers closer to reality, but any number given must still be treated as suspect, or at least "sanity checked" against some simple facts such as the rated amp draw versus the claimed horsepower. Some generalizations on compressors: if you want this unit for anything more than blowing up tires and the occasional use of an impact gun or air hammer, you probably want an oil-sump 2-stage unit. Be careful that you are actually getting 2-stage and not just 2-cylinder--on a 2-stage unit the second stage will typically have a smaller piston diameter (and correspondingly smaller jug) whereas on a 2-cylinder unit both will be the same size. While this is admittedly a generalization, it tends to steer you toward an industrial-grade compressor, which will give you much better service than the homeowner-grade units. Note that you can find twin-cylinder single-stage units that are well-built, but they are not nearly as common and are used primarily for constant running high-flow applications such as sandblasters or factory machinery. In this market, many have been displaced by screw (or similar) units, which might give you a shot at picking one up on the cheap. Don't be afraid of buying used--if it's a good name-brand compressor, parts are usually available, and a good older unit will often outlast a cheap newer unit even without a rebuild.

[Log in to Reply]  [No Email]
Charles (in GA)

01-12-2008 18:44:50




Report to Moderator
 Re: Air compressor help in reply to jdjack, 01-12-2008 15:22:04  
The second and third ones you list are two stage, you won't get 175 psi from a single stage, and a 7.5 hp/25 cfm unit is two stage. I own one and shopped extensively, so you may have mis-typed on that one.

Most air tools are designed to operate at about 90 psi, thats at the tool. Allow for air pressure flow/pressure drop in the hose and you will need to regulate at about 100 psi, so you need a unit with more pressure than that. The CFM specs are for the 175 psi compressor, with the flow regulated to 100 psi coming out of the compressor.

Get the most you can afford, you won't be sorry. If you plan on buying or building a blast cabinet, you need the 7.5 hp unit. As already noted, sanders, grinders, cutoff tools, and the like, use lots of air. Things such as impacts and air hammers use much less air. Depends on what you plan to do, but with compressed air, more is always better.

Charles

[Log in to Reply]  [No Email]
jdjack

01-12-2008 19:58:42




Report to Moderator
 Re: Air compressor help in reply to Charles (in GA), 01-12-2008 18:44:50  
Charles
I those spec are correct. right off machine.
So when they say 100 psi, thats all the pressure that it will build?

I don't understand why some are 100psi and the others are 175 psi?



[Log in to Reply]  [No Email]
circus

01-12-2008 21:03:30




Report to Moderator
 Re: Air compressor help in reply to jdjack, 01-12-2008 19:58:42  
Two stage compressors compress the same air twice. With two piston compressors one is smaller. Thus 175 psi



[Log in to Reply]  [No Email]
circus

01-12-2008 17:22:48




Report to Moderator
 Re: Air compressor help in reply to jdjack, 01-12-2008 15:22:04  
standardized cfm = cfm Get the one with the 2 stage pump. Guessing the one with 175lbs. pressure. It'll be more efficient. You can run two smaller ones. Much more reliable and run one when two aren't needed.



[Log in to Reply]  [No Email]
Wayne_H

01-12-2008 15:46:49




Report to Moderator
 Re: Air compressor help in reply to jdjack, 01-12-2008 15:22:04  
You may also want to look at how fast the compressor actually turns. Cheaper units get the specs up by turning the compressor faster. I bought a 10 year old IR T-30 compressor. It's a real 5 HP, draws 27 amps, and is very quiet and works great. Like my John Deere Tractors, even though it's old I can still get parts for it!

wayne



[Log in to Reply]  [No Email]
shannon from ohio

01-12-2008 15:31:18




Report to Moderator
 Re: Air compressor help in reply to jdjack, 01-12-2008 15:22:04  
Go with the 25 scfm if using the following::Sandblaster,Da-Sander,or strait-line sanders as they are the biggest air users.....



[Log in to Reply]  [No Email]
[Options]  [Printer Friendly]  [Posting Help]  [Return to Forum]   [Log in to Reply]

Hop to:


TRACTOR PARTS TRACTOR MANUALS
We sell tractor parts!  We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]

Home  |  Forums


Copyright © 1997-2023 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy

TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters

Website Accessibility Policy