Replies

1. 
   ring | Mar 05, 2010 09:51am | #1

   BigK,

   Things may be quite different in my neighborhood, so take this with the required grain of salt:  A compressor is just about the last tool that I'd spend my time on rebuilding.  There are used ones readily available of every type and age.   What's more, any commercial shop in my neck of the woods needs to have its compressor inspected regularly.  It just seems to me that going it alone would possibly make that certification more difficult, and time better spent on other machines.

2. 
   JohnWW | Mar 05, 2010 09:00pm | #2

   I'll second the advice you have already been given.  Compressor tank failures are almost always catastrophic, as in no walls left standing, so both your insurance company and the state you live in will probably not be pleased to discover that you have a home brewed air compressor. 

   In many jurisdictions the local or state govenment will require you to have a permit for the compressor and it will need an annual inspection.  They won't issue a permit for a machine that isn't in good condition with the properly sized fittings and safety valves along with a verifiable history and the original paperwork.

   I also doubt if you will be able to find an insurer who will write a policy for your shop if the compressor doesn't have a valid inspection and is otherwise in factory original condition.

1. 
   BigK | Mar 06, 2010 12:15pm | #4

   This reply is for both David Ring and John White. I am not aware of any inspections or permits for air compressors here in Denver. And as a licensed carpenter/general contractor I am fairly well informed about these kinds of things. Denver already has plenty of annual permits that they charge plenty for, annually. Things like $175/year for each welder that your business has, an annual permit that is charged on how much propane that is stored at your shop, $75 for my annual fire inspection, not to mention that my business pays an annual ownership tax on each machine valued over $500 (this after the tax that I/my business paid when the machine was purchased). The list goes on and on. Expenses like these make being a business owner downright expensive. So please, don't give Denver any more ideas on how they can charge me more for the priviledge of  being a business owner, I am not sure how many more of these expenses that I can keep absorbing and manage to stay in business.

   That all being said, I am quite aware that there are several safety devices that are necessary for an air compressor to be used safely. But really, if you sit down and think about it, all of these parts just thread together to create a safe machine. I am not looking to build anything that is unsafe or even dangerous to be around. Heck I am planning on working in my larger shop around this new compressor. If I want to be around something unsafe I can always go out and buy another pre-riving knife Unisaw and try to use it with that joke that Delta calls a safety guard. Oh wait! I already did that once. I am quite sure that my health insurance provider enjoyed paying to have my left index finger repaired after it went into the saw blade one morning.

   And yes, I am quite aware what happens when an air tank ruptures; it becomes shrapnel, something akin to an exploding grenade. Have you ever seen a photo of the destruction that can be caused when a large oxygen bottle falls over and shatters? It looks something like a crater sideways on the side of a hospital with damage extending across three floors.  And I have also helped to rebuild hands that have had a mortar round cook-off in, we are talking about high explosives and shrapnel.

   I logged in and asked if anyone may have had any experience with rebuilding an air compressor. I am hoping to find a little advice or a book on how to do it safely and properly. An air compressor is nothing more then a bunch of parts that all fit together, most via pipe threads. If done properly, and safely, then the finished product can be an asset to be used to assist in the production of wood cabinetry or furniture. My financial resources are not unlimited and if I think that maybe I can save a little money by doing the work myself, then that should be more power to me. I am more then mechanically capable of doing the work as vs. paying someone else $80/hour to do it for me, plus whatever they mark-up what the parts cost.

   I have read about homemade thickness sanders here in Knots. I have even followed the arguments when some "experts" have tried to advise another member of this forum how to wire up large machinery while working with 240 volt 1PH and also 208/230/480 volt 3PH. I think that the most heated discussion was one of those "experts" trying to convince another "expert" on how not being a licensed electrician yet writing a book about shop wiring made him emminently qualified to give advice on how to resolve a technical wiring question. These discusions, that I consider to be relatively dangerous, continued on unfettered to their natural conclusion. I hope that the individual who asked the initial question, and received mixed, conflicting answers, went out and hired an electrician to resolve their problem.

   Right now the air tank in question is under 110 PSI and will stay that way until later this afternoon, it is called an air test. I am trying to figure out how I could possibly get someone to come over to my shop and fill that tank up to 175 PSI as that is the pressure that this tank was originally designed for.

   I am trying to find some literature about the actual pump that I have. Apparently Ingersoll Rand does not keep older literature in their online archives. I beleive that this pump is an early version of their current type 30 2-stage compressor pumps, the only difference is in external parts, things like the intercooler and the flywheel used.  One thing that I am sure of, this compressor is all American cast iron and steel. The pump does turn over freely and it appears to have good compression as I am unable to keep my hand over the outlet for even one revolution. I beleive that if I can find the information that I need, that I can build fairly nice compressor and save myself quite a bit of money in the process. I could hire some shop to do the work for me, at about $80/hour, but that would probably wipe out any potential savings. I might as well go out and just spend $4000 and get a new compressor at that point, like I don't have anything else to do with whatever money I have.

   Apparently you both would be uncomfortable taking on this kind of project, John and David. I am not. I just need to find the knowledge that I have inquired about. I was hoping that one of Knot's many readers might perhaps know of a book or something that would help answer my questions. Thank you.

1. 
   ring | Mar 07, 2010 01:06am | #7

   K,

   You shouldn't infer what isn't there.  I wouldn't be "uncomfortable" with the rebuild you are talking about; I've probably done more outrageous repairs and rebuilds of heavy machinery (including farm equipment) in third-world conditions than most people could imagine.  I just expressed the opinion that your time might be better spent elsewhere.

   best of luck in any case,

2. 
   JohnWW | Mar 08, 2010 09:56pm | #12

   I was not saying anything at all about whether you could do the work and do it competently.  I was warning you that both safety inspectors and any insurer will quite possibly not allow you to use the airtank, no matter how competent your work, in which case you have wasted both your time and money.

   Also a few things you should know about large air tanks and apparently don't:

   1.  The tank will have a specification tag welded to it that gives the date of manuafacture and its rated pressure.  Once that tank has past a certain age, typically ten years, it will have to be retested and recertified to satisfy safety inspectors and insurers.  You may have gotten the tank at a good price because the tank is old enough to need recertifying.

   2.  Vermont, a state which doesn't tend to heavily regulate things, requires that air tanks over a certain size, in certain applications, must have a permit and an annual inspection.  The 60 gallon air compressor tank in the woodshop at a school I taught at had a state permit, that needed to be renewed annually, posted on the wall right next to it.

   I would find it hard to believe that the area that you are in, with the regulations you cited, doesn't also have some serious rules and regulations about pressure tanks.  In any case, a commercial insurance company will almost certainly want to be satisfied that the set up is safe before they issue you a policy.

   3.  Air tanks are NEVER EVER safety tested, as you suggested doing, by pressurizing them with air to the maximum pressure listed on the rating tag, that is an excellent way to get killed.  For testing and certification they are pressurized to twice the rated pressure with water by a certified testing company, if the tank fails there is just a large splash of water, not a building leveling explosion.

1. 
   BigK | Mar 10, 2010 12:26pm | #13

   John,

   I was not aware of testing using water, but that does make sense. I used air as that is what is used to test plumbing in new/remodel construction that is inspected.

   With regards to the specifications tag that you have referred to, that is known as an A.S.M.E. tag (American Society of Mechanical Engineers). That tag is a cerification that is good for 20 years. While I will admit that my air tank in question is just older then the allowed certification date, that does not change the fact that it is holding it's pressure without even a hint of leakage or even seeping. I would be willing to bet that it would not be hard to find a huge number of air tanks that may be older then 20 years that are still in service in both small DIY shops as well in general industry across America.

   I had checked into the possibility that either Denver or Colorado would require testing of the air tank in question, they do not. And I stand by my statement, "please do not give them any ideas". The financial burden of being a small business owner is no small thing. The examples that I had cited are only the tip of the iceberg. If any governmental entity were to pursue every possible regulation and the resulting taxation against business then I would have to beleive that business would have to relocate elsewhere so as to be able to remain competetive and to protect their ability to turn a profit i.e. stay in business.

   All of this discussion matters not as I am abandoning my plan to rebuild this compressor. It seems that someone at the local Ingersoll Rand shop has misinformed me and the compressor pump in question is much smaller then what I was initially led to beleive. I will try to sell off the parts and am again looking for a deal on a good used compressor.

3. 
   Cincinnati10 | Mar 10, 2010 08:41pm | #14

   BigK

   WARNING WARNING WARNING

   PLEASE DON'T TRY TO PRESSURE TEST THE VESSEL YOURSELF. ESPECIALLY DO NOT USE AIR! Vessels are certified with a Hydro Test.

   A welders supply or SCUBA Supply may be able to help. They have to make sure tanks are structurally sound before filling AND BEFORE TESTING. They have the capability to do a visual internal inspection and can wire brush any corrosion or scale they find and make an assessment as to wall thickness in suspect areas. Then a hydro test will be done to certify its structural integrity in holding pressure for a period of time. I can't remember the pressure or length of time for the test, but I'd venture it is something like 2x the rated pressure. Water is used because it is virtually incompressible, so in the event of catestrophic failure, you won't have THE EFFECT of a bomb going off as you would with a compressible liquid like air.

   if your tank is too large for them to handle, Google ASME Pressure Vessel testing sites, or ASME Hydro Testing Sites in your area. I'll bet you will hit paydirt.

   The cost for my last SCUBA tank that I had this done was $15 in the early 90's. I would not have an A/C tank like you describe in my shop without doing this even if there is no regulations mandating it. Choose wisely here.

   Greg Porter

   OK I should have read all the other posts first. You have already been given wise counsel. Rebuilding a compressor may be prudent. Cutting costs with the vessel is not.

4. 
   inventorboy | Apr 08, 2012 12:02am | #16

   solidarity

   Hey Big K,

       I'm in the process of building my own compressor, just finished reading your thread , and I am bursting(get it - compressed air -  bursting . ..  )   with curiousity about the progress with your compressor.

5. 
   woodrouterman | Apr 09, 2012 10:28pm | #19

   I 2nd and 3rd the advice given.  I would not try to rebuild a compressor. It's just really not worth the effort compared to what you can purchase a used one for on craigslist.  Not to mention (as others have) the safety concerns.  Good luck tho.

   Porter Cable Wood Router Reviews

6. 
   gochay | Apr 15, 2012 11:29pm | #21

   air compressor

   Several things come to mind when I read your post and the responses.  First, check hte tank for a certification tag.  This will give you some info on the tank ratings.  Remember that test pressure and working pressure are worlds apart.  IR can probably help you with an appropriate pressure switch for your system.  More than likely, they use the same switch on any number of compressors as the switch would be used to operate a magnetic contactor and not act as the on/off switch, especially if you have a 3 phase motor.  The piping portion of hte setup is the simple part, a nipple out of the tank to a tee with one side of the tee going to the pressure switch and the other to your regulator, dryer, etc.  A good investment would be to put an automatic tank drain to get rid of water that will build up in the tank.  These can be as simple as a float valve mounted below the bottom of the tank to insure all moisture is captured and disposed of.  Really, the most technical part of this project is getting the wiring right as you will need to provide a control voltage to the pressure switch to operate the magnetic starter.  This can come from the supply side of the starter if the pressure switch is rated for it.  Do NOT confuse the starter with the circuit breaker, BOTH are absolutely necessary for proper operation and and electrically isolating the unit for maintenance.  Best of luck with this project and your new shop.

3. 
   BigK | Mar 06, 2010 12:09pm | #3

   Ray,

   I have considered that also. In the interim the air pressure test is a good preliminary indicator for whether this tank is worth any further investmant. I will be inquiring about the possibility of actually inspecting this tank. One possibility is that a plumber friend of mine has a Ridgid(?) See Snake, a fiberoptic borescope that I would bet that he would bring over so that I could get a look inside of the tank. Problem is that every air compressor tank has some rust in it. The $64 question is how much rust would be considered acceptable.

4. 
   BigK | Mar 06, 2010 09:12pm | #5

   Additional good news, for whatever it is worth. The tank has held 110 PSI for 24 hours without losing even an ounce of pressure. While I need to test it at 175 since that will be the working pressure, I am working on that for hopefully Monday.Meanwhile holding 110 is definitely a good indicator.

1. 
   Cincinnati10 | Mar 11, 2010 08:51am | #15

   Please know that 110 psi can produce one hell of an explosion. I pray no one is anywhere close if it fails. Ever stand next to a truck tire at 45psi as it blows? It will be like a balloon popping compared to a 120 gal tank at 110psi. It takes over 1000 gallons of air forced into that 120 gallon tank to reach 110 psi, and nearly 1600 gallons to reach 175 psi.

   I hope you can understand the danger you have even at 110psi. Nearly 10X the tank volume has to escape and once structural failure begins it rapidly builds tearing metal and making shrapnel. The "force" that has to escape is 110 pounds times the surface area of the inside of your tank in square inches. Failure may cause windows to blow out, the room to explode, and/or metal to fly through walls.

   You are making a gamble and may be putting yourself and anyone in the area in grave danger.

   Greg Porter

5. 
   paulbny | Mar 06, 2010 09:26pm | #6

   You might try checking with a local dive shop about someplace that could pressure test your tank.  I doubt they could do it but it would be a starting point. 

   In a former life I used about a dozen IR 2 stage compressors, they are just about impossible to kill.  The 2 mechanics I had working on them kept a rebuild kit for them (rings, seals valves) but had never found one that really needed a rebuild.  If they had failed it was always lack of oil(as in NONE in the crankcase) and they where siezed and completely trashed.  My compressors ran 3 shifts 6 days a week and they were the one thing I never had to worry about. 

   You should be able to get everything you need to bring what you have on line from Graingers.  Even if it has one, replace the pressure valve with a new one with a known pressure value.  Power controls and pressure switches are pretty much generic.

   Good luck with your find.

6. 
   BigK | Mar 07, 2010 03:42am | #8

   I wasn't looking for an air compressor to rebuild, but rather was looking around for a used one hoping to save a little money. This compressor sort of fell in to my lap. It is a little bigger then I need, but I figure that I can probably resurrect it for a little less then what what I actually need would cost new in a decent quality brand. Two side benefits to going this route: if perhaps I change my mind about employees in the future I will have plenty of compressed air to support such a move, and I figure that if necessary I should actually be able to sell this compressor for what I will have actually spent on it.  I am not above a little sweat equity, I built my original shop and am finishing a sizable addition on that original shop right now. I helped to build our new house because my wife was having to many issues with living where we were before. Sweat equity seems to be how I get a little ahead in this world.

   In my experience it is not that easy to find good used machinery at a good price. Auctions take all day and the machinery many times ends up costing more then the same would new. I do troll through a couple of online sites looking for deals in what I need, but the timing usually isn't right. I tend to want better brand equipment that I think/hope will perform better. I am not to impressed with a lot of the asian stuff that is going around, had a bad experience with an import bandsaw that wound up costing me both money and time. I have bought most of my machinery new, but have generally managed to catch much of it on sale or some special deal so that I was able to get a little better value for the money.  I don't really feel that I chose to rebuild this air compressor but rather that opportunity chose me, and that there is a payoff for my time invested. Throw in the fact that I might actually learn something, who am I to argue?

1. 
   sapwood | Mar 07, 2010 12:02pm | #9

   I don't have the url but perhaps that site Old Woodworking machinery will have some info. 

2. 
   dude | Mar 07, 2010 12:15pm | #10

   here in canada we have a outfit called Princess Auto that sells everything from soup to nuts

   since they have come into the area it hardly pays to try to build anything from scratch

   their warranty says " no sale final unless your satisfied " with no time limit

   i hve regularily taken stuff back from years ago with no receipt and get a credit note

   If i want cash back i need a sales slip

   The company mfg a lot of there inventory at prices that are hard to beat

   buddy just made a log splitter that i borrowed , he had the cyl & beam but bought the rest

   Princess had a better one on sale after christmas for the price he paid for the tank ,wheels , motor , pump & control alone & he bought the parts from princess !

7. 
   Don_F | Mar 08, 2010 01:30pm | #11

   You might find all the parts you need at Master Tool Repair/Air Compressor Parts Online , they have a nice web site with lots of help and hints.

   Also try searching hydrostatic pressure test.

   Hope this is helpful , sometimes hardest part is finding the right places to look.

   Don

8. 
   swenson | Apr 08, 2012 12:49am | #17

   If I remember correctly the pressure tests I had done for SCUBA tanks were not only for pressure but more importantly to see if the tank returned to its original size after the water pressure was turned off. This was done with the tank submerged in another testing tank filled with water to the very top. As the SCUBA tank was pressurized it expanded and displaced water that was caught in a collar. Then with the pressure off they tried to replace all the water in the outer tank up to the top edge. If they didn't have room for all of it that meant the SCUBA tank had not returned to its pre pressurized size and could fail.

9. 
   VAM | Apr 09, 2012 07:25pm | #18

   Amazon?

   A search for "air compressor" in the books section yields more than 8000 results.

10. 
    IdahoDon | Apr 14, 2012 01:23pm | #20

    Simply looking at other large compressors will give you an idea of what parts you're missing - not much to a compressor inside or out.  You've got a pressure switch to turn it on and off, a safety valve in case the motor doesn't shut off, an unloader to release air pressure from within the cylinders so it can easily cycle on, and a one way valve going into the tank.

    I'd take it apart and look at the valves - if the everything looks fine I'd simply put it back together.  If the reed valves are somewhat warn you can spruce up the surfaces with some fine grit wet/dry sandpaper on a piece of plate glass to keep it flat.  I'd use 400 grit to start to get it flat, then 800 to remove the 400 scratches, then 2000 to get it polished enough to really hold air well.

    If after checking the valves and the thing puts out plenty of air I wouldn't touch the rings or cylinders.  The rings can be sourced based on size alone, or if you know the model it shouldn't be that hard to get a set.  Simply hone the cylinders, and new rings and you're off to the races - and that's worst case if they even need to be replaced. The home machinist magainzes often have guys rebuilding obsolute engines and compressors - probably some good sources of oddball parts there if the more commons sources aren't turning up what you need.

    I think it's a great project - with a little common sense I wouldn't lose any sleep over it. Keeping an eye out for someone who has worked with commercial-size compressors willing to do a side job and I'll bet lunch that for a very reasonable fee for ultrasonic testing you'll find an older heavy-gauge tank is very workable.

    I'd also keep watching craigslist for various parts - once I saw a fire department getting rid of an old breathing air tank for free - it was something like 200 gallons and weighed well over half a ton if memory serves - perfect for a shop.