Compressor recommendations

5 HP and 115v sounds like an oxymoron. Is that really a 5 HP compressor or is it a marketing gimmick? 15A 115V allows only 2 honest HP. i

Steve,

Typically, determine how much you need to run the tool with the highest air consumption and double it. A good air grinder will use about 8cfm @ 90 psig continuous. Also, if you plan on any future purchases such as a plasma cutter, you will need about 5.5 cfm @ 90 psig.

Stay away from the oil-less units. too loud and short life.

I am familiar with the Home Depot unit you mention. Try to find the next size larger and that may suit your needs. Sam's club sells a Delta unit mounted on an 80 gallon vertical tank, rated for 16 cfm @ 125 psig for about $742.

If you want to go portable, look at HD and Lowes for a gasoline version, sells for about $800.

Good luck.

tankguy

Look at the CFM rating at 90 psi. Ignore the HP. 4 cfm is about the minimum for a shop compressor, 6 is better, 8 or more is better yet. Air chisels and impact wrenches don't use much air, die grinders can use up to 10cfm and you would want to use it continuously. Paint sprayers are variable, I run mine nicely at a regulated 40 psi on a unit rated at 4 cfm.

Do look at the full load amps, theory says 746 watts per hp, actutal is around 900 or 950 watts per hp. 15 amps at 120 volts is 2 REAL hp.

Ignore the oil less units, too noisy, no life expectancy.

Tank size is not really an issue, all a bigger one does is lets you have a few less compressor starts, get one of 20 gallons or better. Upright takes less space, horizontal can be fitted with wheels and trasports easier.

Look for cast ir> I need a compressor. I saw one today at Home Depot that was an upright on

look for a twin piston single cylinder , single stage oil lubricated unit. I have an Air America (devilbiss) 5HP 20 gal, which is about 10-11 years old and stil runs /performs as new. it has a DOERR continues duty / compressor motor on it. aluminum compressor body. horizantal unit on wheels. the biggest think I like about it is that the motor can run on 110V and 220V (with a simple wire switching on the motor and plug) amprage is rated 15/ 7.5A . it runs happy all day on the standard house hold wireing 12 gauge (20 amp) connected to 20 amp braker on 220 V.

air delivery rated 7.1CFM at 90 PSI. I use the same tools you mention, air chissel, air impact gun, grinder, sander... and such. one thing to keep in mind, if you are a single user in your shop such compressor will keep up easilly, since you will to stop very offten, the compresor will catch up . with spray painting, by now you shulld be using low presure high volome spray guns, again the compressor will be fine . however it will not keep up with the old convensional air sprayer if you are trying to paint a car at once.

also invest in a good air filter/ water separating unit. also a good idea to install an auto drip lubricator inline. this will keep all of your air motors driven tools very happy. there is no such thing as over lubricating an air motor.

TIP: I use a T fitting and a separate air hose as a NO OIL line for tire inflation and to use as blow gun on some critical stuff like cleaning dust on the inside of the computer : -) de dusting area prior to painting and such. you don't want to spray oily air in your tire or computers and such.

15A at 110V cannot produce 5 HP. i

You may be right , but that is not the point. I can't change whats printed on the label, unless you want me to spray paint over it.

It does not matter in this case. It runs the compressor pump it was matched with, all day.

The point was that it can run fine just about anything for a single user wants to use in a small shop.

Please don't twist my words, We all know it will not rurn commercial grade jack hammer they use to break up concrate (the oneyou see on the side of the road. )

Well, it's up to you what you would do with your label. But the compressor is not 5 HP. At best, it is 2 HP.

i

Hi

I contributed this on compressors to the WeldingFAQ site

It's been checked over by folk who command respect in these parts so I hope what it says should guide you to your answer.

Richard Smith

Air compressor specs. The "the big lie" They post all kinds of specs to confuse and sell to you. The only spec that is important is CFM @ 90 PSI. (cubic feet per minute) You need about 9 cfm @ 90 psi to do most jobs. Single stage compressors will top out at about 9 or 10 cfm @ 90. If you want more CFM for sand blasting, the switch to a 2 stage compressor. They start at about 10 cfm @ 90 and go much higher. They can also deliver higher top end pressures.

A 2 stage has one large and one small piston. The air is first compressed by the larger piston, them is fed through a radiator, into the second smaller piston. The same volume of air is compressed even more by the second smaller piston. A single stage compressor has 2 pistons the same size. They work in parallel. John ps Look at Emglo compressors. They tend not to lie as much.

In UK context that can draw 13A at 240V from any socket - and max. induction motor power allowed is 3HP (as starts with a "thump"?):

3HP portable gives about 7-8 c.f.m. air at 90psi 3HP fixed gives about 9.5-10.5c.f.m. at 90psi

Difference is mainly because fixed machine has bigger motor which is truer "3HP"

If your compressor is single-stage, that is going to be a reality governed by physics / the laws of nature.

A two-stage compresssor is reputed to pump about 25% more air - never tried one myself.

Richard Smith