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Thread: air compressor

  1. #11
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    Quote Originally Posted by Portable Welder View Post
    They actually say that if you ever decide to fix your own regulators that the natural oil in your hand is enouph to cause an explosion.
    A fingerprint "weighs" about 50 micrograms.

    Assuming 100% of the mass of a fingerprint was hydrocarbon oils (which isn't even close... lots of salts, etc.) and using the heat of complete combustion (oxygenated explosion) of these oils at an average of 50kJ/gram, the energy released in the "explosion" is 2.5 Joules, or 1.8 foot-pounds. That's less energy than a flashlight running for 1 second.

    I'd like to know who "they" are so I can ask them what they get out of starting urban myths.

    Now if we're talking about a gram of oil in the regulator, that's 50kJ or 36,900 foot pounds... 15 times the muzzle energy of a 30-06 rifle round. Now that's something to worry about!

    80% of failures are from 20% of causes
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  2. #12
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    Bodybagger, not saying you are incorrect. Actually I tend to agree with you as I work on HP O2 gear and have never heard about needing to wear gloves during a rebuild. Its the energy part I disagree with.

    All you need is a seed catalyst to begin the combustion. Once ignited almost anything will burn in the presence of 100% O2.

    Here's a couple of picts of an O2 fire.

    haskel3a1.jpg

    haskeldetail1a1.jpg

    haskeldetail2a.jpg

    I had just checked the line and it was slightly warm when this happened. As you can see from the photos something went wrong. Output line pressure was aprox. 1450-1500psi. I wish I could find my before picts. If you look at the bottom of the booster you will see 2 loose lines. That’s what is left of the outlet lines. The 1/2"SS HP fitting that went into the booster, 5 of the SS 1/4" tube to 1/4" npt swageloc fittings that attached the 2 SS HP Tees, and the interconnecting 20" of 1/4" SS HP tubing is GONE, vaporized in an instant. If you look closely you can see the remaining half of the 6th adapter to the first tee in the bottom of the picts. The 2 tees survived but looked like someone burned all the threads out with a torch. I used to have one of the tees but someone walked off with it. My guess from the damage is that the fireball had to be about 24-30” in dia. in order to get all of my arm.

    My hand was just about where you see that partial fitting. 3rd degree burns on my right hand from finger tips to elbow, about 85-90% of my lower arm. Flash charred all the skin but was over so fast there was little depth to the burns. One week in the burn ward and lite duty for the next couple of months, you can hardly see the scars. Small amounts pin point amounts of SS spatter on my upper arm, chest and face. Thank god for glasses! Burns stopped where my skin was protected by my cotton t shirt.

    Even though I was at ground zero there was no concussion, only a fireball. However had something like a tank valve vaporized there would have been serious consequences. The day after I got out of the hospital a woman with whom I was personally familiar, died in an O2 explosion in a shop in Florida. Most likely cause was oil contaminated dirt that entered the valve when the customer dropped the tank in the parking lot. Tank exploded when she hooked up the partially filled tank. Tank valve open, fill valve closed. Several others were injured in the explosion. I'm still looking for my copies of the picts of that tank and will post them if I find them.


    Now what happened. Possible causes,
    1) Foreign matter into system from valve (spider web perhaps)
    2) Foreign matter from system ( piece of brass from valves due to poor maintenance)
    3) Oil contamination from air system (due to poor maintenance)
    4) Adiabatic compression
    5) Check valve failure on output of booster.
    6) Operator error (unlikely due to the fact I was watching the pressure going in and it couldn’t do that if a valve was closed.)

    We talked to the mfg of the booster and sent it to them for analysis. They were unable to determine the cause because most of the lower piston and valve assembly was vaporized in the flash. However they say this is not an uncommon occurrence in the airline industry where they use these boosters to fill O2 bottles for the flight crew. Their solution put the unit in a blast cabinet and LET IT BLOW UP! Go figure. Our sister companies compressor techs believe check valve failure due to similar failures on HP compressors. When the valve fails hot discharge gas flows back into the piston and is recompressed raising the temp. only a few cycles would have been needed to severely raise the output temps.


    The moral of this long winded post is not to underestimate the destructive potential of O2.

  3. #13
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    An air impact is what??? About 10% efficient, maybe 15 tops? Takes 6 to 10 times the energy to compress the air and turn it back to rotary action.

  4. #14
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    Aug 2004
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    Milan Michigan
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    BodyBagger, I certainly dont want to pretend that I know any of the scientific formulus that you seem to know.

    I do know that over the years I have tied to get parts for regulators and they absolutely would never sell them.

    It was about 3 different shops over the years that I was told no too.

    I have also taken classes about torch safety at some of the welding shows that I have went to over the years and I've been doing this for 26 years now.

    So I'm just passing along knowlege that I've been taught at these torch safety classes.

    I've been to the Victor, Smith and Harris classes.

    So you may be right about not enouph oil on your hand to cause a problem but I see no reason to find out the hard way.

  5. #15
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    Feb 2009
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    Metalmeltr, in the meantime I wouldn't be quitting the day job just yet.

  6. #16
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    Wow....I just read the first post on here....

    to quote Homer Simpson "Perpetual Motion??? In this house we obey the laws of thermodynamics!"

    Sorry...I just had to. This goes along the same lines as the battery powered battery charger that uses 6 D batteries to charge 2 D batteries. Or my favorite....the car that runs on compressed air.

    SO lets see....Drill for crude oil...ship to power station....run giant diesel engine to make electricity....transmit electricity accross country to air compressor....compress air.....charge air tank in car.........hmmm
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  7. #17
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    Quote Originally Posted by Aerometalworker View Post
    Wow....I just read the first post on here....

    to quote Homer Simpson "Perpetual Motion??? In this house we obey the laws of thermodynamics!"

    Sorry...I just had to. This goes along the same lines as the battery powered battery charger that uses 6 D batteries to charge 2 D batteries. Or my favorite....the car that runs on compressed air.

    SO lets see....Drill for crude oil...ship to power station....run giant diesel engine to make electricity....transmit electricity across country to air compressor....compress air.....charge air tank in car.........hmmm
    You left out the fan. ...... Electricity turns the fan which blows on the wind turbine which powers the air compressor (he's Amish).....

  8. #18
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    Quote Originally Posted by DSW View Post
    You left out the fan. ...... Electricity turns the fan which blows on the wind turbine which powers the air compressor (he's Amish).....
    This just went from weird...to rube goldberg! I still love the electric car. Hmmm....where is that energy going to come from? *sigh* this is what happens when you let politicians out of their cages and actually make rules and decisions.
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  9. #19
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    I actually think the prius and similar cars (here in referred to as fartboxes) cause more pollution than if they were just a regular IC engine with enough power to get out of their own way.

    See, if you had a normal car in place of the fartbox, you wouldn't have everyone else who encounters said fartbox mashing their gas pedal to go around the pokey turd. So the ecological benefit of the fartbox itself is more than displaced by the resultant harm it causes others to induce.

    The PETA people who advocate vegetarianism and wish to tax cows based on methane produced by said cows have a similar flaw in their logic. The cows fart because they only eat grass. People also fart a disproportionate amount when we only eat vegetation as well (every single vegetarian I have ever met has had a gas issue). So in replacing the meat in our diet, we induce the same end result as the animals we're trying to eliminate. Do we then tax people for farting more? There's a lot more people than cows.

    The vegetation is also what's converting our co2 back into carbon and oxygen, so we should eat less vegetables as they're offsetting the co2 we're all busy exhaling. If you care so much about your carbon footprint, please do us all a favor and stop breathing.

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  10. #20
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    Quote Originally Posted by Mastertig View Post
    Metalmeltr, in the meantime I wouldn't be quitting the day job just yet.
    i am 13 so no job yet I just had severa days off school with nothing to do when I thought of this

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