Air Compressor Recommendations?

[LetsRoll]

My compressor is rated at 24+ CFM at 175PSI.

Dan...that is your pump displacement cfm. What is your scfm? Also, cfm is not calculated at 175 psi, its calculated @90 psi. Most manufactors know most users wont use 175 psi, so its calculated @90 psi. Just some food for thought.

 

[Dan69GTX]

Dan...that is your pump displacement cfm. What is your scfm? Also, cfm is not calculated at 175 psi, its calculated @90 psi. Most manufactors know most users wont use 175 psi, so its calculated @90 psi. Just some food for thought.

You are right - sort of. I used the wrong acronym. And you are right - most manufactures use 90 PSI instead of 175 PSI because the specs look better.

My compressor is a Champion Centurion II Model VRV7F-8 (7.5 HP baldor motor with the RV-15A pump). According to their web site
http://www.gardnerdenverproducts.co...iprocating/Brochures/C1-1-7-220 _5th_1-06.pdf
the specs for my compressor is...compressor rpm 990, 125PSI CFM displacement is 28.7, CFM delivery 23.9, 175 PSI is CFM displacement is 28.7, and CFM delivery is 23.1. My manual shows what I posted but the RPM is greater - just over 1000. However I'm sure specs have changed in the past 5 years.

Just for kicks I looked up Saylor-Beall compressors and they also rate the compressor at 175. Vertical Tank Mounted Air Compressors

It's tricks like that which make comparing compressors difficult. And its the different acronyms that keep people really confused if they don't pay close attention.

 

[VA_Joe]

Dan...that is your pump displacement cfm. What is your scfm? Also, cfm is not calculated at 175 psi, its calculated @90 psi. Most manufactors know most users wont use 175 psi, so its calculated @90 psi. Just some food for thought.

That's correct. Because most tools use either 40 or 90 psi there is really no use for a 125 or 175 cfm spec (doesn't provide much useful info for comparison). All that 175 psi really gets you is more storage in a given volume.

BTW - it is no longer a certainty (as it once pretty much was) that the 175 psi compressor will provide greater CFM output over the 125 psi compressor. The max psi of the single stage compressors are creeping upward without any increase in cfm output (it's the new selling point now that the manufacturers got caught with the horsepower scam).

If someone really needs the capacity and continuous CFM output of a 175 psi compressor - and few do - I strongly suggest spending a little more and getting a quality two stage, oil compressor with either a 60 or 80 gallon tank (I would go 80 - not much bigger sizewise).

Joe

 

[LetsRoll]

My compressor is a Champion Centurion II Model VRV7F-8 (7.5 HP baldor motor with the RV-15A pump).

Wooow...7.5 hp motor. Wonder what that bad boy spike up to when it kicks on? My compressor has a 5 horse motor and I have a 60amp double pole breaker in the box (30amps per leg=60amps total). I know when my compressor is running, the meter at the house is flying. I'd hate to see what the meter is reading if my compressor is running and it had a 7.5 motor on it.

BTW...if you dont mind me asking. What made you purchase a compressor with a 7.5 horse motor on it? 5 horse motor seems like enough for home hobby use.

 

[LetsRoll]

Since I knew I was going be doing a ton of sandblasting, I wanted a two stage and a 80 gal tank. Two stage is the only way to go if you need a ton of air like in sandblasting. When I use a impact or a paint gun, I have to turn the pressure way done. When I use a paint gun, the pressure has to be way done (35-40~ primer or paint). If I blast cast iron or steel that is real rusty, I use 100 lbs. I use about 70-80 lbs for my impacts. I've never used anything above 100 lbs.

 

[Dan69GTX]

Wooow...7.5 hp motor. Wonder what that bad boy spike up to when it kicks on? ........
BTW...if you dont mind me asking. What made you purchase a compressor with a 7.5 horse motor on it? 5 horse motor seems like enough for home hobby use.

The 7.5 motor uses 32 amp run (per leg)..Here are some specs on it:
Full Load Torque 22.5 LB-FT
Break Down Torque 52 LB-FT 231 % of F.L. Torque
Locked-Roter Torque 53 LB-FT
Starting Current (Amps) 184.0

I purchased the 7.5 HP because I don't have 3-phase at the house and it's the largest I could find to run on single phase current. I have a "serious" hobby and do all sorts of restorations, fixing, creating, etc. I knew I wanted it to run my bead blast cabinet, pressure sand blaster, etc. I considered a screw compressor, but most of those only do 125 PSI and I wanted the 175 PSI for operating my tire changing equipment. With 125 there were several times I couldn't easily dismount a tire that was on a rim for a long time. With my sand blaster the unit has a tough time recovering. - which is another reason for the 300+ gal air storage. The guy I bought the compressor from was trying to talk me into the 5hp version. Boy I'm glad I stuck to my guns and got the 7.5. I did a bunch of research and calculations and knew I needed over 20CFM for my max use.

Depending on my media I run 60-100 psi in the blast cabinet. I run 120-125 in the pressure blaster. I use line pressure for the tire equipment and I regulate the air line drops to 100. My spray gun is a Sata NR95 HVLP gun so it requires about 50 psi at the gun (which produces 10 psi cap pressure) it uses 13CFM. I also use my air compressor to feed a full face respirator for painting. (yes it runs through special filters to remove contaminates) So that is another 3-4 CFM for it.

So, yes, I'm very pleased with my compressor.

 

[Iplayfarmer]

I have a "serious" hobby and do all sorts of restorations, fixing, creating, etc.

Yep. That's a serious hobby to warrant that kind of compressor.

 

[The Fred]

Revamping this old thread,

I need a think out of the box idea for an outdoors sandblasting air compressor, my IR 7.5 is NOT big enough.

I want at least 75 CFM @100 psi. and not electric. I have tank space so that's not an issue. I had a VW air compressor but wasn't happy with it the darn thing was VERY loud.

Can you help? Ideas? How about a converted engine? How about something big that would run off a 540 RPM PTO?

I know I know I know I think too much.

Hmmmmm, too much time on my hands, Fred

 

[Scrambler82]

I used the IR 7.5hp, 27 CFM rated, compressor, a nice unit, noisey but more than kept up with my two sand blast cabinets and a lot of power tool work. Sold it when I just moved to SoCal.

You must plan on some heavy duty sand blasting wanting a 75 cfm rated compressor.
My neighbor used a commercial duty wheeled unit, made for major street work, we do a lot of larger pieces with it.
Maybe you can find a used unit for sale from a construction company, that would cover just about any of your needs.

What are going to do,with this BIG compressor ?

 

[buickanddeere]

A cast iron two stage about twice as large as what you think is required.