Hot Rod Forum : Hotrodders Bulletin Board

Hot Rod Forum : Hotrodders Bulletin Board (http://www.hotrodders.com/forum/)
-   Garage - Tools (http://www.hotrodders.com/forum/garage-tools/)
-   -   New Air Compressor (http://www.hotrodders.com/forum/new-air-compressor-124455.html)

blsnelling 09-15-2007 09:14 PM

New Air Compressor
 
Please help me pick out my new air compressor.

I'm in desperate need to upgrade my air compressor. I had a 60 gallon singe-stage until three years ago. I thought I wanted something portable that could run on 110, so I bought a Craftsman 30 gallon 5HP oiless. I hate it! It's so loud you can't talk in the garage when it's running. It takes forever to fill the tank, and it doesn't begin to put out the CFM I need.

The hungriest tool I have is a small blasting cabinet. LINK. I do not use it a lot. But when I do, I can only use it for a few minutes and then wait for the compressor to catch up.

I also use a traditional spray gun to paint with, not a HVLP gun. When painting my trailer it ran constantly.

My most common use is an impact gun, air ratchet, and 1/4" die grinders.

I have two main goals in this upgrade. I need a lot more CFMs and it has to be a LOT quieter.

I'm debating between a single-stage or a 2-stage. I like the higher pressure of the 2-stage for my impact gun. However, the IR single-stage actually puts out quite a bit more CFM than the two 2-stage models. It's pump also turns fewer RPMs. It should run less and be quieter to boot. This particular model seems to put out significantly more CFMs than any other single-stage I've looked out, making it a particular bargain. And also confusing my decision making. I thought I really wanted a 2-stage going into this but am not so sure after finding this IR single-stage. I'd appreciate your advise on this matter.

Here's the compressors I'm looking at.
1. Ingersoll Rand 5 HP, single-stage, 80 gallon, 18.1CFM@90psi, 135psi max, pump speed 1000 RPM, $800
2. Ingersoll Rand 5 HP, 2-stage, 80 gallon, 15.8CFM@90psi, 175 max psi, pump speed 1375 RPM, $1130
3. US General (Harbor Freight) 5 HP, 2-stage, 60 gallon, 15.8CFM@90psi, 165psi max, $829 new, $729 refurb

blsnelling 09-16-2007 09:28 AM

Anyone have any advice?

oldred 09-16-2007 09:40 AM

That particular IR (the first one) has been the subject of discussion here before and there have been many discussions on how the compressor builders tend to exaggerate their claims. There is simply no way that thing will produce that kind of CFM at that pressure and those numbers are nothing more than sales tactics arrived at by using "smoke and mirror" engineering to estimate performance. At 5 HP and the fact that IS a good single stage pump, for a single stage anyway, I think around 12-14 CFM would be a lot closer to fact. If you can afford the extra cost of the two stage then don't even consider the single because in addition to better CFM on a given HP rating it will run quieter, cooler and last longer, the second IR you list is a good choice and the numbers should be a lot closer to real than on the first one. Might I suggest you check out the Eaton compressors as they are a REALLY good compressor at a good price and you can believe the numbers they claim. When looking at the Eatons, and there are other good brands, it may seem like the performance is a bit low per HP than some of the competitors when in fact the opposite is true because they tend to tell the truth, we have become so accustomed to seeing the non-sense numbers from most outfits that the real performance does not look all that impressive. Almost all of the "econo" compressor outfits exaggerate the performance almost to the point of ridiculous and in some cases so bad they have landed in court over it but most of the really good companies like Eaton, Quincey (my personal favorite) and even IR are much closer to the truth but IR has been guilty of fantasy numbers on some of the smaller models like the one you listed. Some of the things to look for would be an American made motor such as GE or Baldor and a pump with a low RPM design whether you go with two stage or single. A 60 to 80 gallon tank is about right for a compressor in this power range and a 60 will perform just as well as the 80 as far as running tools so don't base your decision on tank size. Avoid any compressor that lists "peak" or "max developed" HP numbers as these are pure non-sense and proves the compressor is lying about performance, likewise walk away from anything that lists "tank assisted" CFM as this is the biggest scam of all. The 80 gallon will offer a slight advantage in service life and power consumption due to fewer start/stop cycles during any given use period but this advantage is VERY slight and not worth spending a lot of extra cash for. It certainly would be a BIG mistake to pass up a better performing pump/motor to get a bigger tank but this happens all the time and the builders of these things know that a lot of people will buy the biggest tank they see so over-sized tanks are common. Remember CFM (true CFM and not phony numbers) is what will make your tools run and big HP numbers and a huge tank don't mean squat if the CFM is not there.

blsnelling 09-16-2007 04:55 PM

Why would we believe the number on one IR and not on another? I thought they were touted to be a reliable company with a long history? Has anyone bought this single-stage IR to disprove its claims? Would anyone have links to someone with experience with this compressor?

You mention that the 2-stage IR would be quieter than the single-stage. They both have the same motor. However the motor pulley is larger on the 2-stage causing it to run 1375 RPM instead of teh 100 RPM the single-stage runs. So the 2-stage is running fast and compressing higher pressure. Wouldn't that make the 2-stage louder and hotter?

Another thing. It makes sense to me that the single-stage can put out more CFM than the 2-stage. If you look at the cylinders on the pump, you will see that the cylinders on the single-stage are both the size of the larger cylinder on the 2-stage. It would only stand to reason that it would compress more. If you take one of those cylinders and make it smaller, as on the 2-stage, you're now making greater pressure but at a lower volume. Does that make sense?

SteveU 09-16-2007 07:05 PM

I have the single stage 2 cyl Eaton & the pump & motor on this thing is huge compared to any of the compressors you see at the box stores. I have run all the tools you mentioned & more and have never had to wait for air. Just got a 90* aircat die grinder & after oiling it & putting a HVLP fitting on it held the button down on it until the compressor kicked on at 110 psi, it slowly built to 125 psi & stayed right there while holding the die grinder running full blast. It will pump up & shut off while running a 6" DA sander, 1/2" impact, 3/8" air drill, air hammer, 3/8" & 1/4" ratchets, air cutoff, etc. It is quiet enough to have a conversation approx 10' away from the compressor while it's running without having to shout to be heard. Pump speed on this is 650 rpm, rather reminds one of an old tractor idling when it runs as opposed to the jackhammer sound of an oiless. I really like quiet which is why I'm replacing my noisy air tools with aircat (think air ratchets not much louder than an electric drill, other tools are similarly quiet) combined with this compressor working inside without earplugs isn't a problem. Read a review on another site of a guy that has the 5 hp 2 stage Eaton, he is just as happy with his as I am with mine :thumbup:

blsnelling 09-16-2007 07:55 PM

Is THIS it? What's the max psi on this unit?

oldred 09-16-2007 08:24 PM

Quote:

Originally Posted by blsnelling
Why would we believe the number on one IR and not on another? I thought they were touted to be a reliable company with a long history? Has anyone bought this single-stage IR to disprove its claims? Would anyone have links to someone with experience with this compressor?

You mention that the 2-stage IR would be quieter than the single-stage. They both have the same motor. However the motor pulley is larger on the 2-stage causing it to run 1375 RPM instead of teh 100 RPM the single-stage runs. So the 2-stage is running fast and compressing higher pressure. Wouldn't that make the 2-stage louder and hotter?

Another thing. It makes sense to me that the single-stage can put out more CFM than the 2-stage. If you look at the cylinders on the pump, you will see that the cylinders on the single-stage are both the size of the larger cylinder on the 2-stage. It would only stand to reason that it would compress more. If you take one of those cylinders and make it smaller, as on the 2-stage, you're now making greater pressure but at a lower volume. Does that make sense?


Buy what you like but the advice I gave you is based on nearly thirty years of selling and servicing compressors and air systems. As far as the two stage vs single stage a good two stage design will out-perform a comparably powered single stage because it is a more efficient design. It will run cooler for the same reason and also because it will dissipate some of the heat during the second stage of compression. Comparing the piston sizes is meaningless because they operate on a different principle, the two stage partially compresses the total volume of air with the large cylinder then transfers it to the smaller piston where it is then compressed even further to higher pressure before being discharged into the tank. The single stage simply compresses the air directly into the tank with each piston operating independently of each other as far as compression is concerned, kind of like two single piston pumps working together on one tank and motor. As far as the truth about CFM ratings again believe what you like but that single stage is aimed at the small home type shop and the two stage is more of a commercial unit so the sales tactics are different for two differer markets. I have tested the flow on quite a few compressors in the last 30 or so years with a bunch of them being in the 3-5 HP range with single stage pumps and I can assure you I have never seen a single stage with only five HP put out anywhere near that much CFM. With any given amount of HP you can you can get high flow and low pressure or low flow with high pressure but you can not have both, not with a single stage anyway. It is just like having a car with one gear, you could have high acceleration but no top end or you can have a high top end and no pulling power. On a single stage compressor a compromise must be made and about 13-14 CFM@ 90 PSI is about all 5 HP is capable of with a piston design and that IR is a simple piston design. If you want to believe those numbers they list for that single stage then it is your money so buy it but I would bet that a good Eaton single stage with 5 HP would produce as much or more, probably more, (they have a better V pump design) and it will be rated somewhat less. Again it is your money but that CFM number is a sucker trap even though the compressor is very well built and will last a long time, it has so much else good going for it that it is a shame they had to be so reckless with the truth about performance.

blsnelling 09-16-2007 08:47 PM

Thanks for the detailed reply. I got the response I expected, and wanted. No offense intended. I'm just trying to pick your brain in order to learn.

Anyone looked at this model? LINK

SteveU 09-17-2007 01:33 PM

That's the one. Mine kicks on at 110 psi & runs to 140 psi where it shuts off at. Takes 52 seconds to run an 80 gal tank from 110-140 psi, one day I will bleed it all the way down & see what it takes from 0-140 but never measured it during the initial fill & read where it wasn't good to drain tanks often so haven't let it get empty since. Remember to budget in for hardline piping such as copper, galvanized or black pipe, NEVER PVC!!! If you just plug a hose directly into the compressor you will have water coming out of the hose everytime you use it. This seems have been a bigger problem with my compressor before doing the hardline than it was with my buddies hotdog compressor, maybe it's the bigger tank size?

blsnelling 09-17-2007 07:33 PM

I'm looking at these two Eaton units and it looks to me like this single-stage is putting out more CFM than the 2-stage as well. Single-Stage 2-stage . Am I misinterpreting the info? Why doesn't Eaton rate their compressors at 90 psi like most everyone else. It makes it difficult to compare apples to apples.

66GMC 09-17-2007 08:57 PM

Eagle Compressor - MaxAir 18.5 CFM


Eagle - Max Performance - also 18.5 CFM

Oldred (and others) ... what do you think about these ones?
I'm thinking of one of these for my garage.

One of my (small) bodyshop customers has one of the blue ones ... and says it seems pretty good ... and doesn't take long to "catch up" after a period of high demand.

I recently sold him one of these
http://www.aquachekfilters.com/wps/t.../main-text.gif
WIX "Aquachek" filter systems ... he seems to like it so far, as well.

oldred 09-17-2007 10:40 PM

Those things are good outfits but even though it has a very efficient 3 cylinder V-type pump I would still be a bit skeptical of the CFM rating although it will probably be close, a heck of a lot closer than the IR single stage 2 cylinder in-line design. Trying to figure out compressor performance can give a fellow a real headache, for example compare that Eagle unit to a comparable Eaton-they are both "heavy duty" 5 HP motors that are rated at running HP and not the "peak" nonsense that the cheapo outfits use BUT the Eaton is 25 AMPs. Both are 5 HP but the Eaton is more powerful, go figure. This is what I mean when I say Eaton tends to tell the truth about it's products (as does the Eagle) and compared to most it would seem they actually underate some of the specs but this is because of the non-sense we have been accustomed to. Now you asked about the Eagle not Eaton and I am not trying to plug for Eaton I just wanted to make the point about the differences and why specs vary so wildly on compressors that appear to be almost the same. In the real world the performance of the Eagle and the Eaton would be vary close and I think you would be very satisfied with either compressor you listed and either one will out produce the so called 6-7 HP cheapo units by a large margin. You could easily wear out several of the common economy compressors of the same (claimed) power rating as the ones you mentioned before they would need attention and have a much better air supply in the mean time. :)

blsnelling 09-18-2007 06:24 AM

What's the price of the Eagle?

66GMC 09-18-2007 06:56 PM

I'll have to check to make sure ... but I think we have it "sale priced" at around $1200.00 CDN.

The "Canuck Buck" is just about on par with USD right now (0.9859) ... the highest it has been in more than 30 years ... but I haven't noticed the prices getting any more reasonable. :(

Cripes ... I think I'm going to book a trip to Hawaii!
I think the last time we went to Florida ... the buck was worth about 0.67!

blsnelling 09-19-2007 03:27 PM

What's your opinions on this compressor for $900 used, 1 year old? LINK 1 I was surprised to learn the the motor RPM is 3500. Isn't that a little high leading it to be loud? Can someone confirm that? What about the pump RPMs?

Comparable to the above is the following. LINK 2 It's motor only turns 1800 RPMs and the pump turns 800 RPMs. I'm thinking it would be much quieter. Am I putting too much emphasis on the RPMs?

I'm also looking at the following 5HP models. Anyone know the RPMs or have an opinion on these?
Campbell Hausfeld
Ingersoll Rand
Eaton


All times are GMT -6. The time now is 12:04 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.