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  #16 (permalink)  
Old 08-23-2005, 01:00 PM
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250 Psi

Quote:
Originally Posted by oldred
I know one guy who runs 250 PSI in his 40 gal tank on his service truck!)
Wow! Can he spell shrapnel?

We had a motor failure on our fairly large (8 HP?) compressor which is mounted in an enclosed "penthouse" above our wash bay at work. We purchased a slightly different (re-wound) motor for it, and had an electrician and his apprentice come in to re-wire it.

The apprentice got assigned to the task, while the electrician and I "supervised" (translation: BS'd) on the shop floor. We had the compressor running for quite a while, and Terry yelled up "So how are things going up there?"

"Oh, pretty good ... it's just about up to 250 ..." was the reply. Terry SCRAMBLED to the breaker panel, and yelled to me to "release some air ... quick!"

Our shop air is plumbed in black pipe ... which apparently is not rated that high, according to Terry.

Next the apprentice tells us that the compressor has been spraying oil everywhere. Terry claims that was unrelated to the over-pressurization ... which I disagreed with. We'd never had a problem before with oil leaks. Anyway, seeing as how we are leasing the building, I left it to the landlord to settle, and ordered in a IR 5HP 80 gal "temporarily" until it gets settled. That was 4 years ago.

So satisfy my suspicion ... was it because the cut-out switch was somehow bypassed and the system overpressurized that caused the oil leak?

Thanks,
Don

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Last edited by 66GMC; 08-23-2005 at 01:01 PM. Reason: spelling
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  #17 (permalink)  
Old 08-23-2005, 01:22 PM
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I have never seen Eaton play that phony numbers game like so many of the cheap compressors do so I think you can expect what Eaton says it will do. In all probability the problem is in that "10 CFM" DA since those cheapie outfits DO play with the numbers! If you can get hold of a really good DA, make sure it is lubed properly and the air regulated to the proper setting and I think you will see an amazing difference but if it is a faulty compressor then rest assured Eaton will not let you down.
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Old 08-23-2005, 01:38 PM
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66, I will assume you are talking about a piston type compressor and if so that much pressure could very well cause a leak like you describe from the pump itself if the case vent were not up to the task of handling that much blow-by. You did'nt say how big that tank was but if it was about 80 gal or bigger you didn't have a large bomb there is was more like a nuclear device! To put it in perspective I once saw a 40 gal tank rupture at about 175 PSI(due to rust damage) and it peeled open a Mack truck cab, I mean it destroyed that thing! It was mounted behind the cab and when it ruptured it blew parts of that cab 50 feet away and laid the top over the hood! There was one guy on this site tried to explain why that was just not possible but I saw it myself I know what it did.
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  #19 (permalink)  
Old 08-23-2005, 02:25 PM
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Quote:
Originally Posted by jcclark
Bondoking: you need to go back and read what Oldred said,
Bigger tank or higher pressure doesn't get you anything.
After what I've read and understand I'll definetly keep mine
at going off at 150 psi. like Eaton recommended

Jim Jim Jim I tought Eaton said 130 for that compressor?????? Do I need to change the battery in my whisper 2000 hearing aid???
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Old 08-23-2005, 04:32 PM
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JC,
This may be a long shot but...... I bought a 7-1/2 3 phase Speedaire compressor a while back. I got it wired up to my new phase converter and turned that thing on. In very little time I recognized that the output was not much better than my old unit which was rated at 11 scfm at 90 psig. I got a real good deal on the Speedaire (Used) and began to suspect why with the low output. I started looking around and saw that one intake filter had some dust on it and the other was like it had just that minute been put on. I removed the filter bracket so I could see down in the Pr and found that a plastic plug had been put in at the factory before painting and never taken out. I removed the plug reassembled the filters and boy did that thing start pumping air. Just a thought take a look at your unit. David Bodily
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Old 08-24-2005, 08:22 AM
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Another question for you compressor guru's.
Will a tank last longer if you drain out all the air
every day verses just draining out the water?
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Old 08-24-2005, 09:44 AM
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No it won't help it will just add unnecessary wear to the pump/motor. Might I suggest an automatic drain? I have one that came from Harbor Freight on my Ingersoll in my garage at home p/n 46960-7vga for about $17.00. They have one for around $10 dollars but it is rated at 100 PSI max but then we are only talking pennies anyway. I don't know what the max pressure is on the one I use but my compressor max is 150(6 HP two stage in case you may be interested) and it works just fine.
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Old 08-24-2005, 10:56 AM
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JC, Actually I didn't think to mention it earlier but completely discharging a tank every day will theoretically shorten the life of it due to metal fatigue from excessive expansion/contraction. A tank will expand slightly each time it recharges and contract upon discharge but regular cycles are not as drastic as complete discharge.
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Old 08-24-2005, 11:12 AM
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Dang and here I thought it would lengthen the life since you are reomving the moisture and allowing air to flow both ways through the valve.... Red you are the man!!

BK
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Old 08-24-2005, 11:45 AM
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Guy's, I thought I would pipe in for a moment... as I was reading this tread I was surprised at the large number of folks considering or suggesting upping the pressure on your stock air compressor. As others that have replied to this thread have pointed out, some compressor company's are not as "high grade" as others, so this means their tanks are not either. As oldRed stated about the tank bursting, this could happen very easily... I have a Sanborn 6HP, 80gal tank, single stage, my compressor kicks on at 90psi and shuts off a 120psi. I would like more cfm as well as pressure, but the tag on the side of the tank states very clearly max tank pressure is 150psi. so I really can not mess with it. Of course there is some safety factor built in but my point is, you should check to see what the rating of your tank is first before you up the pressure. Some tanks may not be able to handle it and you really do not want to be standing beside it when it does burst... Where I work, we pressure test housings that we build, these housing can be built from any number of thicknesses of materials, from #10ga. to 2" pl. our standard criteria is to pressure test up to 138in-H2O (which equates to approx. 5 psi... yes only 5psi.) anything over that pressure get Hydrostatic pressure tested. (they fill housing with water, water absorbs the energy, so the housing just splits at the weld seams or somewhere in the middle of a panel, usually where there was a flaw in the material) this is all for safety. All I'm saying is, be careful, if some young fella logs on and reads this thread and chooses to pump his pressure to 250!!! well it could be fatal...

Sorry, I was just concerned... thought I would throw my 2 cents in...
Bill
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Old 08-24-2005, 12:21 PM
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Festive,
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Old 08-24-2005, 12:48 PM
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Holy crap, there is a ton of misinformation on here about pressure and tools. I do tons of work in the commercial and industrial market with compessor manufacturers analyzing compressed air SYSTEMS for more efficient operation. Never have I been in an installation that REQUIRED more than 100 to 110 setpoint at the compressor to operate any equipment you would normally see in an industrial application downstream of it. Never have I been in an installation where they would even consider operating the compressor at 175 to 200 PSI, that would be absurd, and extremely expensive.

I have worked and evaluated systems from 10 HP to 2500 HP, at companies like J Deere, Alcoa, Charter Steel, Briggs, GM and others. If you can build a car, tractor, forge wheels and make steel with 100 to 110 PSI air I suspect we should be able to tinker with our cars at home with the same, which you can.

What you need is volume to run tools. If you can run a DA for 25 minutes without a problem I'd say your in pretty good shape. After that period the line is probably spitting water and you'd want to stop anyway. The only thing a comressor does better than compress air is make water.

Air tools only need 90 PSI at the tailstock to operate properly and a peak efficiency. Therefore, if you have your compressor set 150 to 175 and it won't run the tools, it's not a compressor pressure problem. It's volume or a pressure drop in the line. I see this ALL THE time.

Unless you have some whoop de whoop super duper odd ball one of a kind tool 90 PSI tailstock pressure should be more than enough.
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Old 08-24-2005, 01:22 PM
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I thought that too, all the tools I've seen said 90 psi.
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  #29 (permalink)  
Old 08-24-2005, 02:01 PM
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Rick, That is EXACTLY what I have been saying. I did not mean those guys at the mine were doing the right thing and I have warned repeatedly about the folly of overpressure but some people just will not listen. I see it all the time, someone will come into the shop and say "my compressor will not keep up with my 1" drive impact how much will you charge for a bigger TANK!" or "do you have a regulator that will allow me to run 200 lbs" . It seems too many people want to believe that more STORAGE translates into more compressor CFM and I have trouble making them understand that storage will not make up for insufficient pump CFM. In this case we were discussing extra tank pressure being used as extra tank volume not extra pressure at the tool and my point is that TANK volume no matter how it is obtained is not going to make up for a compressor that is too small, at least not after running more than one recharge cycle. If the pump CFM is low it is a small compressor and will perform like a small compressor even if you do up the pressure or add extra tanks. As for running 150 PSI on large tools like 1" drive impacts that much pressure will make a difference just not as much as most want to believe but running that high above the recommended pressure is common practice here,right or wrong, has been for years and I assume it will remain so. The efficiency drops off dramatically above a tool's designed operating pressure so a huge increase in pressure only amounts to a small increase in performance but this is often enough to make it worth it to some so as I said they will continue to do this. Also 175 PSI cut-off pressure is commonly found,from the factory, on two stage compressors with 60-80 gal tanks and 15-20 CFM range that are sold for small shops although some are less than that and I think what started this discussion was if raising the designed cut-off pressure would be beneficial or not and I think that at this point everyone understands that volume and pressure are two different things but getting more VOLUME to run tools was the original subject not more pressure at the tool. I don't see where anyone even suguested running more pressure at the tool and the examples I gave were to show how common it is for some to misunderstand the problem and the extremes they will go to.
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  #30 (permalink)  
Old 08-24-2005, 08:39 PM
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Out of curiosity,is there some way to determine what cfm your compressor has at 90psi ? I mean some way other than some expensive air flow tool? I bought my compressor some years ago and have long since lost all my literature.

Thanks,
Bill
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