Air pressure vs velocity

If you have two air tanks, 1 with 90 psi and 1 with 150 psi but regulated to 90 psi at the outlet would the air velocity be the same for both tanks or would the 150 psi tank have more velocity because there is more pressure behind the regulator?

would depend on the type of regulator used, and if the tank without the regulator wont be at 90 psi very long..................

richter69 wrote:would depend on the type of regulator used, and if the tank without the regulator wont be at 90 psi very long..................

I am trying to understand why shops use two stage air compressors that have higher pressure (typically 150-175 psi) but most air tools are 90 psi. With the higher pressure you could fit more air inside the same size tank but is there any benefit at the tool level? Do your air tools work better Jon? I am trying to find out if the extra bucks for a two stage compressor are worth it.

I think you would be more interested in cfm. You want the most scfm or acfm you can afford and if you have the extra money you want to add a dryer.

I do a lot of compressed air systems from 30,000cfm to 25cfm maintance shop compressors.

From low to high quality compresors: (Piston) single stage, two stage, screw type, (cetrifigal) 1,2 & 3 stage. They do make a three stage piston compressor but they are mainly found in the Med Gas, HVAC services (oil less).

I do think that having the storage tank at a higher than needed air pressure is both a cfm & storage deal. To have longer tool run times before a compressor has to fire again you either have to have higher stored air pressure numbers behind the reg, or a larger storage tank (or both).

IIRC my ancient POS compressor fires somewhere around 90lbs & cuts off at about 125-130lbs with the reg set at about 85-90lbs for a lot of the tools.

Well my old 3 hp 30 gal deal is on it's last leg so I was wanting to upgrade to a bigger compressor that would last all my needs for the rest of my life. I looked at Quincy units as well as Eaton compressor. The Eaton deals seemed to cause some stir a few years ago about where they were made but as far as quality everything I could find online was they worked well. Both are 5 hp motors with the standard 7.5 hp size compressor. They use the larger compressor and slow it down to 600-800 rpm to keep the noise down and last forever. They are both 5 hp and 19 cfm on the single stage and 17 cfm on the two stage. The Quincy unit shows 15.5 cfm at a little higher rpm rate. Both have replacement parts available should repair be needed. I am cheap but I don't mind spending a few extra bucks if I am getting my moneys worth.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130463757045&ssPageName=STRK:MEWAX:IT#ht_3062wt_905

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=400179467767&ssPageName=STRK:MEWAX:IT#ht_3100wt_905

http://www.aircompressorsdirect.com/Quincy-2V41C60VC-Air-Compressor/p855.html

I dont know if you have ever seen one of these up close, but they run so quite, you dont have to turn the radio up when its running.

http://www.aircompressorsdirect.com/Ingersoll-Rand-UP6-5-150.230-1-Air-Compressor/p2417.html

Curt wrote:I dont know if you have ever seen one of these up close, but they run so quite, you dont have to turn the radio up when its running.

http://www.aircompressorsdirect.com/Ingersoll-Rand-UP6-5-150.230-1-Air-Compressor/p2417.html

$4000.00 Crap I would just have to step up to some bigger speakers................

I really like Quincy compressors and don't forget that there are shops that refurbish old compressors. This is the route I would go if I had the money for a new compressor. Also keep in mind the voltage setup you want to run.

jones wrote:I really like Quincy compressors and don't forget that there are shops that refurbish old compressors. This is the route I would go if I had the money for a new compressor. Also keep in mind the voltage setup you want to run.

Quincy is the way to go. We have them on our service trailers, shops, and in the back of our pick-ups.

IDT-572 wrote:

$4000.00 Crap I would just have to step up to some bigger speakers................

He said he didn't mind spending a few extra buck$ for a good one!

Curt wrote:

IDT-572 wrote:

$4000.00 Crap I would just have to step up to some bigger speakers................

He said he didn't mind spending a few extra buck$ for a good one!

I said ( I ) would have to..............

jones wrote:I really like Quincy compressors and don't forget that there are shops that refurbish old compressors. This is the route I would go if I had the money for a new compressor. Also keep in mind the voltage setup you want to run.

That is a good tip about a refurb one. I will look around town but off hand I don't know anyone that does this kind of thing.

Curt wrote:

IDT-572 wrote:

$4000.00 Crap I would just have to step up to some bigger speakers................

He said he didn't mind spending a few extra buck$ for a good one!

hahahhahhaha, I would say you guys are crazy but really it is my fault for not specifying my price range. When I say a little more I mean $1500 vs the home depot style for $900. Maybe Blake could find me one. All the money I would save could pay for a visit to his place.

jasonf wrote:

jones wrote:I really like Quincy compressors and don't forget that there are shops that refurbish old compressors. This is the route I would go if I had the money for a new compressor. Also keep in mind the voltage setup you want to run.

That is a good tip about a refurb one. I will look around town but off hand I don't know anyone that does this kind of thing.

Curt wrote:

IDT-572 wrote:

$4000.00 Crap I would just have to step up to some bigger speakers................

He said he didn't mind spending a few extra buck$ for a good one!

hahahhahhaha, I would say you guys are crazy but really it is my fault for not specifying my price range. When I say a little more I mean $1500 vs the home depot style for $900. Maybe Blake could find me one. All the money I would save could pay for a visit to his place.

I will keep my eyes out for you one.

Several guys on the board have seen mine, It's a 20 hp V4 2 stage compressor 175 psi that originally had a 20 hp 3 phase motor on it. I bought it for $200.00 and swapped on a 10 hp 240 volt single phase motor. Probably bought another $150.00 worth of belts sheaves and taper bushings. It turns half speed from factory rpm.

Was 640 rpm now it turns 330. That's where it pulls full load amps. It should last as long as I'm around.

Fills a 120 gal tank from zero to 165 psi in less than 8 min. Don't know if thats good bad or indifferent, but it does all I need and more..............