3000 PSI Compressor for scuba???

[reverendjonas]

I found this in the local craigslist...I have never seen anything like it before. Is this for real, and if so, what motor would I drive it with? I have been looking for a 60 to 80 gallon compressor lately, would this be a good place to start, or would it not be worth the trouble, and buy something that would fit my needs. I am moving into my first house in about 3 months and will have access to a 40amp (I believe) 220 vac outlet for a compressor.

P.S. This is my first real post. I have really enjoyed reading everything everyone has to say on this board. I look forward to what there is to say about this.

http://phoenix.craigslist.org/wvl/tls/1673556066.html

ingersol rand 15CFM @ 3000 psi compressor, old but still runs fine, could be used as a regular compressor but more suited for paintball or scuba application.

 

[Steve in Mi]

Similar compressors were/are used for starting jet aircraft. I'm most familiar with Worthington 4 stage compressors pumping 4,000 psi. These units were powered by 24 HP Wisconsin 4 cylinder engines and could put out 15 CFM at 4,000 psi.. Rule of thumb 2:1 Gasoline engine HP to Electric motor HP plus accounting for different final pressure ... I'd estimate maybe 10 HP electric motor.

Filtering for scuba air is required and expensive.

For comparison; I have a 4 cylinder compressor rated at 30 CFM @ 150 psi. with a 10 HP motor. It was setup for tractor PTO drive when I got it w/120 gallon tank and compressor trailer mounted. My plan was to convert it to motor drive. Plans change and this one will probably be a Craig's List entry one of these days.

 

[BioHazard]

I really don't think that would make a very good shop compressor...unless you actually want to run your tank at 3000 PSI...

 

[akdiesel]

I believe you are comparing apples to oranges. This is for breathing air for the smaller tanks so they don't really put out that much air (cfm) since they have smaller cylinders to compress the air for those higher pressures.
The typical shop air compressors have larger bores to push more air at a lower psi.
In other words I believe you would be wasting your time trying to modify this for shop use.

 

[TheGrooveking]

CFM is CFM, but you must factor in psi, using the formula C for cfm and P for pressure and A for total airflow.

So C x P = A and if you raise P you automatically get more C, read the specs on your existing compressor(s) you'll notice that the compressors cfm output increase as you lower the pressure. So if your 5hp puts out 11.6 cfm @125 psi, it probably will put out 14 cfm at 80 psi.

So with this you can deduce that it will produce a much higher cfm at a much lower psi, the main difference is that it is designed to work/produce higher pressures. Now the key is that the used compressor runs well, also the pressure controls must be correct and NEVER neglect to install pressure safety vavle(s) on your tank.

TheGrooveking

 

[nate379]

We have a 3000psi compressor at work and and it looks nothing like that. It's quite large, around 5x5 feet or so. 4 stages and a huge motor on it. 3 phase. You can tell when it kicks on cause the lights in the office dim down a bit.

 

[Gizzy]

I was on the local fire dept. for 5 yrs.This is similar to what we used to fill our backpack tanks,called a cascade system.I think for the time & money I'd consider a box store type.Just my thoughts.

 

[Zrexxer]

I think for the time & money I'd consider a box store type.Just my thoughts.

AMEN. Get a compressor that is designed for your use instead of trying to cobble together something unsatisfactory and potentially dangerous from a specialty castoff. Walk away from that and start saving your nickels and dimes for something more practical.

 

[nolatoolguy]

Those bad boys usally work for cascade systesm and not sure about the moters i know there both gas and electric. There not exactly for regular compreser work, its like using 10 inch lag bolts as finishing nails.

 

[MarcSeattle]

+1

3000 psi could really do some damage. Unless your goal was to create explosions.

 

[nolatoolguy]

+1

3000 psi could really do some damage. Unless your goal was to create explosions.

and you cant use just the airhose at homedepot for 3000 psi that stuffs burst piont is like 300 at ahomedepot

 

[reverendjonas]

Thanks for all the replies. This was really just a thought, the pump not costing much, and I knew where I could find (2) 80 gal tanks for $50 each.

My thought process was similar to what has been mentioned here...if it is 15 cfm at 3000 psi, it would be much higher cfm at a lower psi where I would be running the compressor. Add a 5hp 220vac motor, and I would have a high cfm compressor with an 80 gal tank for $275 + the price of a motor and some tinkering. The thought was to run a pressure switch to turn on the compressor at 150psi and off at 200psi.

I know a store bought compressor would be easier, but where is the fun in that. Isn't the motto around here 'Go Big or Go Home'? I just wanted to ask the question around here to see if this is even doable. If it is, cool; if not, no big deal.

Thanks again for the input. I still look forward to hear what more there is to say about this.

 

[kf4zht]

I have seen a few that had the second or third stages removed so they only got to a couple hundred PSI and put out a lot of air. That being said the mods were always done by a tech that really knew these things.

Every one that I have used either had around a 20hp gas engine or a 3ph electric

 

[NUTTSGT]

For $225, you're half way to a decent compressor, now add the tank, regulator, motor. . . . . does it even work ? get the picture ? Walk away from it and buy a regular air compressor. Saving a few bucks is not always worth the time and hassle.

 

[travisd]

I was on the local fire dept. for 5 yrs.This is similar to what we used to fill our backpack tanks,called a cascade system.

FWIW, a cascade system generally refers to the storage bottle arrangement that is actually used to fill SCUBA/SCBA tanks. The idea is that you use the compressor to fill the bank bottles all at once - run the compressor for a longer period, possibly overnight and not try to run it each time you fill a cylinder.

The cascade cylinders are arranged in multiple banks, each isolated from the others by valves. This allows you to fill tanks that are close to the PSI capacity of the bank without having to run the compressor frequently. You allow the first, lowest-pressure bank to equalize with the destination cylinder. This might, for example, get you to 2000 PSI. Then you move to the 2nd bank and get to 2500 PSI - then you can use the 3rd bank to bring it up to working pressure (3000 PSI or higher).

If you just had one bank, then you would quickly end up without enough pressure in the bank to fill to capacity. By using multiple stages, you can draw more volume from the lower pressure set and conserve the higher-pressure sets.

 

[lawfarm]

I agree with Travis on the terminology of FD refill systems.

With regard to the original post, looking at that compressor's size, I can feel pretty confident in saying that there is no way that is a 15CFM at 3000 PSI compressor. It is waaaaaay too small. Frankly, given the size of the heads and hardware on that unit, I'd find it hard to believe that it is a 3000 PSI compressor at all (although the pulley on it looks pretty serious).

 

[bimmer1980]

I would be a little worried about the fact that it is separated from the rest of the components. Generally, the only reason to pull a compressor off would be if it was not working.....

I would recommend looking for a good used compressor that is complete.

As "attractive" as it sounds to build a compressor, I'd rather have a good smaller one that works every time rather than a waiting on a monster compressor that may or may not run right.

 

[kartracer23]

When I worked at a SCUBA shop, the compressor (huge thing off an aircraft carrier) was mounted in another room, behind a double thickness concrete block wall, with a steel plate where the hoses came through into the fill room. You don't mess around with 3000 psi. I've seen a couple of tanks go off - not pretty. Most of the time it's some 'stud' trying to heft one over his shoulder and dropping it on the neck. Instant missile unless the burst disk happens to go before the neck.

 

[Falcon67]

Sounds perfect for a potato canon.

 

[Jim Johnstone]

I know this is an old thread, but I thought I'd fix some mis understandings. The CFM of a scuba compressor likely wouldn't increase at all if you were pumping to lower pressures.

Air compressors generate all their volume (CFM) in the first stage of the compression. So in a single stage 3 piston shop compressor, you have 3 decent size pistons sucking in air and pushing it into the tank.

In a multi stage compressor like this (or a two stage shop compressor) they have a first stage piston(s) that **** the air in, pump it into a smaller second stage piston(s) which then increase the pressure, but don't increase the volume.

That scuba compressors first stage probably makes about 80psi before it dumps it into the second stage. So even if you set the pressure switch for 200 psi, I'd expect you'd get almost exactly the same CFM at 200 psi, as you would at 3000.

Thanks for all the replies. This was really just a thought, the pump not costing much, and I knew where I could find (2) 80 gal tanks for $50 each.

My thought process was similar to what has been mentioned here...if it is 15 cfm at 3000 psi, it would be much higher cfm at a lower psi where I would be running the compressor. Add a 5hp 220vac motor, and I would have a high cfm compressor with an 80 gal tank for $275 + the price of a motor and some tinkering. The thought was to run a pressure switch to turn on the compressor at 150psi and off at 200psi.

I know a store bought compressor would be easier, but where is the fun in that. Isn't the motto around here 'Go Big or Go Home'? I just wanted to ask the question around here to see if this is even doable. If it is, cool; if not, no big deal.

Thanks again for the input. I still look forward to hear what more there is to say about this.

 

[SuperSocket]

When I worked at a SCUBA shop, the compressor (huge thing off an aircraft carrier) was mounted in another room, behind a double thickness concrete block wall, with a steel plate where the hoses came through into the fill room. You don't mess around with 3000 psi. I've seen a couple of tanks go off - not pretty. Most of the time it's some 'stud' trying to heft one over his shoulder and dropping it on the neck. Instant missile unless the burst disk happens to go before the neck.

That's a little overkill for 3,000 PSI. The double wall might have been there or just added some sound deadening value.


Most people do not realize that Paintball is an application for this where people run with tanks as high as 5,000 PSI and jump, fall, dive with. Most common fill pressure is 4,500 now, 3,000 is what we consider to be low pressure and is not as desired


It's not as dangerous as people believe and you do not need bunkers, steel doors, and concrete walls to house the systems. Several fields here just use shipping containers (cheap, secure, and waterproof means of storage) or old trailers to house the cascade systems (usually there is a two stage system, 3,000psi and 4,500psi).


Even in this sport, 3,000PSI compressors are not as desired anymore.

 

[kartracer23]

That's a little overkill for 3,000 PSI. The double wall might have been there or just added some sound deadening value.


Most people do not realize that Paintball is an application for this where people run with tanks as high as 5,000 PSI and jump, fall, dive with. Most common fill pressure is 4,500 now, 3,000 is what we consider to be low pressure and is not as desired


It's not as dangerous as people believe and you do not need bunkers, steel doors, and concrete walls to house the systems. Several fields here just use shipping containers (cheap, secure, and waterproof means of storage) or old trailers to house the cascade systems (usually there is a two stage system, 3,000psi and 4,500psi).


Even in this sport, 3,000PSI compressors are not as desired anymore.

I don't know that it's as much the pressure as the volume of the air contained in a tank and the sudden release of that volume that is dangerous in an enclosed space. If I explode a bike tire at 100 psi in a 20' x 10' room, it's not going to matter. If I explode a 20' long, 10' diameter tank @ 100 PSI in a 20' x 10' room, there's going to be nothing left.