Air compressor pump time - 30gal

[strutaeng]

Hello guys, I haven't posted in a long time.

I'm trying to determine the CFM on this compressor that I've built. The tank is a 30 gal. CH that was dying. I put a Curtis single state pump that that is rated at 37 CFM @ 125 psi. They recommend a 7.5 to 10 hp motor at around 800-900 RPM. I'm running it with a 5 hp Baldor motor (1 3/8" shaft) at around 550 RPM. I have timed the pump time from 0-125 psi to be 1:38 min and 95-125 psi about 18 sec.

Is there an equation that I can use? Or do I need a sophisticated instrument (that I can't afford)?

Does anybody have a 30gal gas compressor and has timed the pump time? All I need is a rough estimate.

 

[metaleltr]

If you know the size of the piston bore and stroke i can get you a formula to determine pump cfm

 

[EOC_Jason]

Here's a page of useful formulas that I think will allow you to work it out...

 

[strutaeng]

If you know the size of the piston bore and stroke i can get you a formula to determine pump cfm

Great, I love this forum!
Bore: (3)3.94
Stroke: 2.75

 

[metaleltr]

area of piston x stroke x rpm x number of pistons/ 1728= Displacement in CFM

 

[pipsters]

30 gal / 7.48 = 4 cu ft
30 psi rise (125-95) / 14.7 = 2 atm
60 secs / 18 secs = 3.33 "per min"

4 cu ft X 2 atm X 3.33 = 27 CFM @ ~110 psi +/-

Sounds like a perfect compressor to me! I have thought about building something similar.

 

[EOC_Jason]

Pictures please!

 

[strutaeng]

30 gal / 7.48 = 4 cu ft
30 psi rise (125-95) / 14.7 = 2 atm
60 secs / 18 secs = 3.33 "per min"

4 cu ft X 2 atm X 3.33 = 27 CFM @ ~110 psi +/-

Sounds like a perfect compressor to me! I have thought about building something similar.

Here are some photos. I call it "La Bestia."
I have completed the wiring and added a pilot unloader so that the motor doesn't cycle on-off in short intervals; the thing just idles quietly once it reaches 125 psi.

The pump itself weighs 267 lbs and the Baldor motor another 100! I actually bought two identical pumps from some guy that buys a going out-of-business auctions.

Designed and built in the USA!

 

[pipsters]

No pics are displaying

 

[Bob C]

I put a Curtis single state pump that that is rated at 37 CFM @ 125 psi.

Ok, I'm curuius as to which model this baby is. A single stage pump pushing 37 CFM (Continuous?) at 125. Is this a screw or a piston pump? A screw I wouild believe but not a single stage piston pump, unless it is one I've never seen.

 

[strutaeng]

No pics are displaying

Sorry, photos were too large.

Anyways, here they are. Note how my Hobart Ironman 210 is dwarfed by the size of this thing.

 

[strutaeng]

Ok, I'm curuius as to which model this baby is. A single stage pump pushing 37 CFM (Continuous?) at 125. Is this a screw or a piston pump? A screw I wouild believe but not a single stage piston pump, unless it is one I've never seen.

It is a single stage piston. Curtis model ES-100.

 

[Outlawmws]

If it was 37, before at recommended speeds, then its about 60% of that (based on the RPM change you gave) so about 22 CFM @125

 

[mryyc]

I'd be terrified of that thing. I hope you're putting a chain link fence around it Seriously though, that thing's gotta move some air, nice job.

 

[metaleltr]

That is a heck of a pump for a 30 gallon tank!

 

[Bob C]

It is a single stage piston. Curtis model ES-100.

Have'nt seen that pump from Curtis before. I mostly sell their screws with some of the 5hp and 7.5 hp 2 stage machines. Nice Build! Now do some sandblasting and make it work hard.

 

[EOC_Jason]

Based on the fill-up time he gave I calculated around 24 +/- 2 CFM (depending on his elevation)...

That looks so funny... big pump on little tank...

 

[Bob C]

Based on the fill-up time he gave I calculated around 24 +/- 2 CFM (depending on his elevation)...

That looks so funny... big pump on little tank...

Yeah, well about 2 years ago we had a 240 gallon horizontal bare tank sitting in the showroom. A salesman sat a little 1 hp air pump on it. Got lots of comments about it. I was gonna put a 1 hp motor on it and see if it would sell. Probably take 2 hours to get to 125psi.

 

[strutaeng]

Okay guys just a follow-up:

I hooked up my Texas Blaster with a 1/8" nozzle and the compressor was actually producing more CFM than was being consumed. They list this nozzle 23 CFM consumption at 90 psi. Unfortuntelly, I was exceeding the amp draw of the 5 hp Baldor because my overloads were tripping.

Fast forward: I swapped the 5 hp for another 10 hp Baldor, but kept the same pulley ratio. It works great now!

I also built a belt guard to hide that "big ol pump," LOL!

Here are some photos.

 

[KinzeMech]

Awesome Frankenpressor.

That thing just screams "Fat guy in a little coat".

If you knock it over, I hope you got fast feet.

The pilot unloader is a neat idea. Should help cool down the pump if it's run long enough to get warm. I bet it also help to remember to shut off the compressor when leaving the shop!

 

[strutaeng]

Awesome Frankenpressor.

That thing just screams "Fat guy in a little coat".

True, but the 30 gal size fits perfect on my garage corner.

If you knock it over, I hope you got fast feet.

It actually is quite stable.

The pilot unloader is a neat idea. Should help cool down the pump if it's run long enough to get warm. I bet it also help to remember to shut off the compressor when leaving the shop!

This is exactly why I added it: to keep it from cycling a lot (since I have a small tank) and to keep it cool. I love these head unloaders. The pilot valve can be closed to run as a dual-mode just like those Emglo/Jenny's, although this will be my dedicated "high volume" compressor for blasting and HVLP spraying. I've got another little guy for nailing and filling tires.

I've got a sister pump that I going to put up for sale, if anyone in N. Central Texas is interested. PM me.

 

[RCStocker]

You can buy an IR compressor with a 7.5 hp moter but they are playing games with the hp. Your pup is designed to run on 3 phase power.
The largest hp you can run on 110v is 2hp
The largest ho you can run on 220 is 5 hp.
Any labels oer those are all false. There are 3 ways of rating HP
It is physicaly imposible to run moters with HP over these limits on this voltage.

You have over kill. Look for a larger vertical tank. That will cut way down on the recycling.

 

[larry_g]

.
The largest hp you can run on 110v is 2hp
The largest ho you can run on 220 is 5 hp.
Any labels oer those are all false. There are 3 ways of rating HP
It is physicaly imposible to run moters with HP over these limits on this voltage.

.

Bull ****

lg
no neat sig line

 

[KinzeMech]

The largest hp you can run on 110v is 2hp

Assuming a common 15A receptacle, running on a 20A breaker, that is correct (but pushing it to the absolute max, and will require good wiring to avoid popping breakers

The largest ho you can run on 220 is 5 hp.

Incorrect. 7.5HP and 10HP 220V electric motors are very commonly used on grain handling equipment in agriculture. I've installed numerous 7.5 and 10HP motors on small grain augers and belt conveyors. It takes large wiring, we typically use 6 gauge to make up the power cord, and put a welder plug (220V, 50 amp) on the end.

Beyond 10HP, the size of wiring required gets pretty ridiculous, but 15HP is possible. Due to the size of wiring necessary to carry the load, it's not common, but it is possible.