Air compressor differences

[Bart Leetch]

I am considering 2 different 60 Gallon Air compressors.

1. Sears 3.2 running HP claimed.
2. 150 PSI max
3. 2 cylinder oil lube pump 12.4/10.2@40/90 PSI.
$449.00

1. Porter Cable 7 HP claimed.
2. 135 PSI max
3. 2 cylinder oil lube pump 14.2/9.7@40/90PSI
$449.00

Is it just the difference in PSI Max that makes a difference in SCFM?

[Mike Cutler]

Bart.

The long answer is, No. The max pressure may give a little bit of reserve capacity in the form of excess process/inventory in the tank. All things being equal, if two tanks that are pressurized to 135psig, and 150psig, respectively. The tank at 150psig will have a slightly longer run time initially. After that it is a matter of the internals of the compressor. The chambers, piston/diaphragm, internal orifices. Loader and unloader valve sizes, air inlet and outlet port sizes and the delta across the compressor.

The short answer is that unless you are planning to run a lot of Pneumatic sanders, air hammers, needle guns, or air grinders. You probably won't notice a difference in compressor cycling. Those are some pretty good numbers on both of those units.

My only reservation is in the HP ratings of both units. If the numbers are accurate the stress on the motor for the PC should be less than the Sears unit, but I don't know how the respective companies are arriving at the HP rating.

[Bart Leetch]

Thanks Mike

I am planning on using a small sand blaster from time to time.

[Ken Garlock]

Bart, you need to look at the Ingersoll-Rand compressors. One of those will be the last compressor you will need to buy in your lifetime.

IMO, I would not buy either of the two you have listed. You need a true 5hp motor on a compressor, not something that will draw 25amp with a locked rotor.:mad: With IR compressors you get a real, no BS, 5 hp motor. Take a look at Northern Tool (http://www.northerntool.com/webapp/wcs/stores/servlet/category_6970_87), they have an excellent list of IR compressors. There is a 5hp 60 gal. IR on sale for $799.:)

[Al Willits]

Running it on short runs I'd be tempted to get the Sears unit, probably much easier to get cust service with them, if not, the others bigger motor would be my choice.

Also, with the bigger motor adding another air tank to increase capacity shouldn't be as much a strain on the unit, if needed.

Al

[Jim Andrew]

Bart, I have found there is a huge difference in the quality of air compressors. Some have a life of 5 years, and some last a lifetime. Listen to Ken. Jim

[David Rose]

Bart,

I just went through that. My main purpose for the new compressor is the blast cabinet. Mine is a small cabinet, but it says that it requires 12cfm. I was torn between the IR at 799 and the next one up which is more industrial. I ended up chosing Shulz because there is a local company who sells and services them. The guys found me a used unit with 3 months on it for about 2/3 the normal price. If you have that option, I would consider looking around. I had no idea that the company was here until a Creeker told me.

My current compressor is an OLD Sears unit that is a true horse and a half. Look at the amp draw. That will more likely tell you the true HP. The old Sears unit will run the blaster for about 10 seconds on its 12 gallon tank. Within less than a minute, it is dropping in pressure too low to power the gun.

David


Thanks Mike

I am planning on using a small sand blaster from time to time.

[Mike Cutler]

Bart, you need to look at the Ingersoll-Rand compressors. One of those will be the last compressor you will need to buy in your lifetime.

IMO, I would not buy either of the two you have listed. You need a true 5hp motor on a compressor, not something that will draw 25amp with a locked rotor.:mad: With IR compressors you get a real, no BS, 5 hp motor. Take a look at Northern Tool (http://www.northerntool.com/webapp/wcs/stores/servlet/category_6970_87), they have an excellent list of IR compressors. There is a 5hp 60 gal. IR on sale for $799.:)

That's something that really bugs me, The HP marketing game that companies play, There needs to be some form of a uniform standard so that consumers can make an educated choice/ comparison without needing to be an EE.

It's not just in woodworking stuff either, ie routers ( a real pet peeve of mine). It's in every consumer product market out there.

Bart.

If you are planning on running a sandblaster, on a more than infrequent basis, You may want to consider adding a seperate reserve tank to the setup sometime in the future.

[tod evans]

bart, i`ll go with ken and david here......i don`t think either of those units are going to be enough for a sandblaster. a reserve tank dosen`t allow the pump to make-up the pressure any faster, with a reserve tank once the pressure drops and the pump kicks on it`ll just run longer to replace the air. there are lots of good compressors on the market ir is only one, salor-beal, quincy, kellog ect. if you`re serious about making air and want to do it once stay away from the retail giants and go to a compressor dealer. i`d rather spend my money on a 20 year old salor unit from a reputable dealer than on 5-6 of the type units you mention. spend some time on the phone, find a local dealer you get along with, go look at what he has, if he doesn`t have what you want/can afford, then wait and stay in touch.......02 tod

[Kyle Kraft]

I recently saw Northern has a small rotary screw unit that is interesting. Kaeser also has a nice small rotary screw unit, and I'm sure the other big mfgrs do too.

[CPeter James]

I also would look around for a good quality used industrial unit. There are air compressor shops in every decent sized city and some some towns even. In the next town to me (about 4,000 people) is a place that repairs and sells units to all kinds of places including ski areas for snow making. Their prices are less than on line. Check around, there are lots of very high quality units out there just looking for a new home.

CPeter

[Kirk (KC) Constable]

I have the PorterCable, and have also installed an 'equivalent' IR. For another hundred bucks or so, go with the IR. Although I never noticed any 'operating' difference between the two, the IR looks to be better made. A lot less plastic.

As a side note, my PC shuts off automatically at something over 135lbs. I wanna say closer to 160, but I haven't paid attention lately.

KC

[John Scarpa]

I went with a Quincy Air Compressor. They are one of the original compressor companies that focus on industrial applications. They only build this kind of equipment and are at the top of the heap for reliability. A few years back they were rated Number one by Wood Magazine. The one they rated had a small tank, mine is a 60 gal. they are a bit pricey, but you pay for the best. This distributor eases the pain with free shipping. I got mine there ordered it and recieved within just days. I have no affliation with them. Good luck on your choice

http://www.bobstools.net/Store/25Q151C60VC3.html

[Bart Leetch]

Thanks guys I think a little waiting is in order here for the Ingersoll-Rand . I've only one bullet in the gun it'll have to get a bit bigger if I'm to make this in one shot.


Bart, you need to look at the Ingersoll-Rand compressors. One of those will be the last compressor you will need to buy in your lifetime.

IMO, I would not buy either of the two you have listed. You need a true 5hp motor on a compressor, not something that will draw 25amp with a locked rotor.:mad: With IR compressors you get a real, no BS, 5 hp motor. Take a look at Northern Tool (http://www.northerntool.com/webapp/wcs/stores/servlet/category_6970_87), they have an excellent list of IR compressors. There is a 5hp 60 gal. IR on sale for $799.:)

[Jim Becker]

Bart, the IR 60 gallon unit I have has a street price of about $550, which is not that far out of your cost range...the wait should be short. You can buy it from Tractor Supply or Northern Tool. (The latter typically has free shipping on it and the former you will pay sales tax)

[Bart Leetch]

Hi Jim which model IR compressor do you have?
Ingersoll Rand Electric Stationary Air Compressor — 3 HP, 10.3 CFM At 135 PSI, 230 Volt, Model# SS3L3 or Ingersoll Rand Electric Stationary Air Compressor — 5 HP, 18.1 CFM @ 90 PSI, 230 Volt, Model# SS5L5

I'm looking at the SS5L5 because I have a small sand blaster I want to use. I ran a friends compressor similer to SS3L3 & it just couldn't keep up.

[Brad Schmid]

Bart,
I have the SS5N5. I got it from my local Tractor Supply for about $740. I also have a Northern Tool local to me but they were about $50 more at the time. The SS5L5 and the SS5N5 that I looked at both had the same IR SS5 pump and the same 5HP motor. The only difference I could tell between the two was the tank size. L= 60gal, N= 80gal. I think the L was slightly cheaper, but not by much. I have a TIP 99 pressurized sandblaster (1/8" nozzle) and the SS5N5 handles it no problem. It will go from empty to 135psi on the 80 gal tank in about 4 minutes.

[Dave Lehnert]

Just FYI Sears are made by PC/ Devillbis. They were when I got my Sears unit

[Phil Ordway]

The HP question turns up regularly on this and other tool group postings. Use 12 Amps for 1HP at 110VAC and 6 Amps for 1HP at 220VAC. This will be close enough. I assume that since manufacturers will lie about their HP, they'll lie about their CFMs. If this is to be a lifetime purchase, I would only get a two stage, belt driven compressor. For single phase power, that means 220VAC 3-5HP or 18-30 Amps. You will find that with a little looking around you can put together a used three phase industrial two stage compressor with a rotary converter for less than $1000. Once you set up your three phase converter, you're ready to look at all those really cool three phase industrial tools that are comparitively inexpensive at auction.

[Bart Leetch]

The HP question turns up regularly on this and other tool group postings. Use 12 Amps for 1HP at 110VAC and 6 Amps for 1HP at 220VAC. This will be close enough. I assume that since manufacturers will lie about their HP, they'll lie about their CFMs. If this is to be a lifetime purchase, I would only get a two stage, belt driven compressor. For single phase power, that means 220VAC 3-5HP or 18-30 Amps. You will find that with a little looking around you can put together a used three phase industrial two stage compressor with a rotary converter for less than $1000. Once you set up your three phase converter, you're ready to look at all those really cool three phase industrial tools that are comparitively inexpensive at auction.

I'll stick with the 5 HP 60 gal IR compressor. Most of the time it will be a little bit over kill for my shop but on that special occasion I won't be stuck with not enough air.

[Jim Becker]

Bart, mine is the SSL3. I hear you on the sandblaster...you need to purchase a compressor that has the air required for the tools you intend to use. I'm sure that you'll LOVE the "next one up" in the line...truly a great compressor!

[Perry Holbrook]

Bart, I run a bench top sandblaster with a 2HP Sears compressor. It works for me because I'm working on small pieces so as I pause between the pieces the compressor has time to catch up. Also, are you aware that siphon type sand blaster guns come with 2 different size nozzles, a 5 cfm and a 12 cfm. I use the 5.

Over on another forum (glass) one of the sand blasting experts recommends the machine Jim has. Of course a pressure pot sandblaster uses less cfm than a siphon system.

Perry

[Bart Leetch]

My sand blaster is a small pressure pot style.

[Perry Holbrook]

The SSL3 will easily run a pressure pot.

Perry