exactly how big of a compressor do I need for a air/hydraulic pump?

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I got a $110 harbor freight 10,000 psi air/hydraulic foot pump today. Hooked it up to my 150psi 2.6cfm @ 90psi pancake compressor.I put a 0 to 4000psi gauge on the pump and then hooked up my pipe expander tool to it. stepped on the pedal and hear the tool working , sounds just like a impact driver.the needle on the pressure gauge didn't move a hair. After a few seconds the compressor kicks on.the pipe expander tool doesn't move at all either.I look at the instructions and this little pump is supposed to have 7cfm at 110 to 120psi.I looked at harborfreight and a compressor to pump that much air is several hundred bucks and huge.maybe I'm doing something wrong, as I've never used a hydraulic tool beforeany ideas?http://www.vansantent.coresense.com/...9#.US7kFTdTHTois what I am trying to get working.
Reply:You're right, that pancake compressor won't cut it, bet a 20 gal air tank would work because of the air reserve, probably not much smaller. I took a quick look at the manual for that machine, on page 6 it goes through the priming procedure, is it possible that the unit still has some air in the system? Page 1 details the venting procedure, this too, may be an issue. Last issue: is there enough hydraulic fluid in the resevoir to fill the ram? Last thing I noticed is that you said your compressor is regulated to 150 psi, not that this could necessarily cause the problem that you are experiencing, but other issues may rear their ugly heads down the road because of it. The manual suggests that you regulate to a MAX of 125 psi. Last suggestion is to tighten down all fittings with t-tape or dope applied, you may be pulling in false air from a lose connector. Nice machine!  Last edited by bearston; 02-28-2013 at 01:21 AM.When a welder tells you to "stick it", what do they really mean?"In a time of universal deceit, telling the truth is a revolutionary act." - George Orwell
Reply:Interesting, on my air over hydraulic shop press air pressure seems only to effect the 'pumping speed'. The strokes just take longer at 60psi than 120 and it still seems to operate the press fine unless it really needs lots of force maybe...  and this is all coming from a 2hp compressor.Welding/Fab Pics: www.UtahWeld.com
Reply:I would think just about any compressor would work, simply because you are probably not running it constantly on. I had one for a homemade bender and I would just use it in short intervals.  Even a pancake would run it, just not for very long.  If it was going to be on for several minutes at a time that would be a different story.
Reply:"I would think just about any compressor would work, simply because you are probably not running it constantly on. I had one for a homemade bender and I would just use it in short intervals. Even a pancake would run it, just not for very long. If it was going to be on for several minutes at a time that would be a different story. "That's what I thought. I read the instruction manual. I'm going to reread it and see if I can get it going with my pancake compressor if not than I will spend $350 and get a HF 29 gallon one.
Reply:I will try mine with a pancake tommorrow.  I dont know if it will help or not, it depends on how big the cyl is, and how much you would need to cycle it.  You can't run a huge cylinder just because the resevoir isn't big on your pump.
Reply:You need at least a "real" 2Hp compressor , not a "peak" crappy one.. Even a Ingersol Rand got chinese pump and motor but they don't boost their spec like cheap "no name" one, a 20 or 26 gallon is not critical as long the pump push more then 7cfm at 100lbs in it...Miller MM211Esab Mini Arc 161LTSEsab Handy Plasma 380Duck tapeTy- rapKool-aid
Reply:You could plumb a larger tank to your smaller compressor to get the extra CFM you need for a period of time before you need to let the compressor catch up. I did this with my 2 HP compressor and can run my spray painter for 10-12 minutes or so before I need to let the compressor build up again I have a 25 gallon tank hooked to it. You just need to have the volume of air built up before you start using it for a while. A bigger tank is cheaper than the $350 for another compressor and tank, if you don't mind waiting every now and then for the pressure to build up again. If you only use it intermittently then no big deal anyway.
Reply:I got a harbor freight 165$ 21 gallon  2.5 HP model 67847 compressor that does 4.7 CFM @ 90 PSIWell below the 7cfm 110psi-120psi.and of course the stupid harborfreight hydraulic pump did not workspoke to HF on phoen and they say the only comrpessor they sell is $800 for one that delivers that much air. Guess it doesn't pay to be cheap in this case. I think I'll return both the hydralic pump AND the compressor tomorrow and just buy the real one from Hoth. Funny thing is Hoth does not say in their manual how big of a compressor you need.
Reply:Did your system need to be purged?  You may not have oil in the line.  I think you are crunching air.Last edited by tapwelder; 03-04-2013 at 08:36 PM.
Reply:All the air over hydraulic does is trade time for higher pressure.  If you had the time to waste you could run it with a hand tire pump.  Big pressure fast takes horse power.  Just curios but why not buy a regular hydraulic pump to run your tool?  They are cheap in the long run. Mac
Reply:If you are just running a small ram, once or twice, the pancake will work.  If you want to run it back and forth continuously, you need a bigger compressor. I started out with the HF air/hydr pump you have. It worked for a year or so, I finally spent extra on an enerpac unit.
Reply:Like I said before this is my first hydraulic tool. I am a newbie at this.How do I purge the line? Just hang the entire line pointing towards the sky so air floats out? When I rejoin it to the pump I'm bound to get a little air in the line right?I did purge the HF air/hydraulic pumpI did not get a hydraulic pump because I never knew that was possible. Looking at them at northern tool a cheap $160 hydraulic pump needs a cheap $160 3HP electric motor. $320 total, so it's actually a bit more, but maybe is more reliable long term? I just need to make 20 pipe expansions over the course of a week, so no high volume usage. I'm going to try and purge the line first any further guidance on how to do that is appreciated.
Reply:You don't have to bleed or purge the line, after a couple cycles it will bleed itself.  It sounds like if you have hyd fluid in it and air and it's still not working, you have a faulty pump. I don't think there are any valves on it or other potential obstructions. I would send it back for either an exchange or upgrade.  Your design is fine for the volume you are talking about, I wouldn't build an electric one from scratch for it. They do make self contained electric units, but you don't really need it for the low volume you are talking about. Like I said I ended up exchanging my HF for an Enerpac eventually.
Reply:thanks for response. so another stupid question:IF I open the bleed valve on the harbor freight air/hydraulic pump and turn the thing on and step on the pedal, it should leak oil right?If it doesnt' leak oil it is faulty right?
Reply:My OTC air/hy pump will self retract.  I will simply pump the pedal back an forth several time until the cylinder moves.  Sometimes it takes a while.  That web  site you posted has a procedure for purging too,
Reply:Here is a pic of mine on a modified HF bender. The pedal has 3 positions. Pressure, hold, and retract. Works fine for that size cylinder but probably wouldn't have a big enough reservoir for a larger one Attached Images
Reply:A cheap pancake compressor ran the pictured pump for about 15 seconds before it dropped to 90PSI. probably enough for one bend before waiting for air pressure to build up again. So if your just doing 1 at a time it might work but you would want a bigger compressor if your cycle times were quick between swages or bends.
Reply:THANKS! I called up the pipe expander tool company and they verified a cheap pancake compressor would work with thier $510 air/hydraulic pump.I'm thinking this harborfreight one is defective.http://www.northerntool.com/shop/too...6258_200446258is a $314 pump that has a max of 3900 psi, a tad over the 3000 max for the tool, but much safer range. All the other ones are 10,000 psi.800-837-3818 mile-x.com800-255--6107 isnweb.comsage southern automotive garage equipmentamazon.com carry it for a bit less.Last edited by AluminumWelder; 03-06-2013 at 12:56 PM.
Reply:Except for our jaws units, I have never seen an off the shelf 10,000 PSI hyd pump.  Usually they are preset at 3000-3500 PSI. They are right on the compressor, you may have to wait a while for it to build up pressure, but it will get you started.
Reply:I just put one on a bender I was selling.It didn't work either until you open the vent.You HAVE to get that vent open or you won't build any pressure.  You will be trying to put the fluid under 'vacuum' and since it is incompressible/unexpandable it won't go anywhere.   You need to let air in to replace the fluid as it moves out of the reservoir.  Once I got it open, it worked like a charm.  If you unscrew the lower body of the vent, that is where you fill it with additional hydraulic fluid.  Also, I removed my ram, put it on the floor and had the pump on the workbench to bleed it through some cycling.  Ended up adding half of one of those containers of hydraulic fluid to it.Again.  Check that the vent is open.BTW, as you're pumping, the fluid level below the vent will be leaving to go into the cylinder, so will be going down.  When you're retracting the cylinder, any air in the line or excess fluid will then bubble out of the vent/fill hole.  If you start to get fluid out of it, on retraction, you've probably maxed out on your fluid fill.I that doesn't work, you have a faulty unit.I almost returned mine until I figured out to leave the vent open while using.Last edited by thordehr; 03-06-2013 at 10:18 PM.
Reply:Do not Confuse the pressure the tool produces to the pressure the pump puts out.  the tool may produce 10000 lbs per square inch, but the pump does not produce that much. #000 lbs is considered fairly high pressure. But by the time you multiply 3000 times the square inch surface area of the top of the piston the pressure you are working with is much higher.    Mac
Reply:"i have never seen an off the shelf 10,000 PSI hyd pump. "well i've been looking for weeks and all the AIR&HYD pumps are around 10,000. The electric motor plus 2 stage HYD pumps are much lower. IF you know of a unit that would work please let me know name/model!@Thordehr, Ill try your suggestions , thanks
Reply:thoredehr, what rating was the compressor you were using?
Reply:I have a big triple cylinder 220V 80 gal unit but I'm sure it would have run off my pancake compressor once I got it figured out and bled.If you have the time maybe try it on Your pancake??I retried mine and it draws down the oil about a half inch and then can't get it any furtherI'm beginning to think maybe the instructions were right?
Reply:You're right about the 10,000 PSI max output. Again if you're only doing 1 at a time it doesn't matter what size compressor you have. You just have to realize you may have to cycle it once or twice to get the job done. If you don't want to cycle you either need to store more air in another high pressure tank or get a bigger compressor. A bigger compressor has nothing to do with the pressure just the volume of air at that pressure.
Reply:I don't have mine anymore, I was playing with it just before selling it and the extra bender I had otherwise I would experiment with it some more for you.
Reply:Well I wound up returning the harbor freight one and I bought one from Northern Tools for $285 with a$30 off coupon which has a max 3900 psi rating. Using the Huth tube expander it works great for expanidng my 1.5" AL tube. At around 3000 PSI the gun leaks some hydraulic fluid. So I am keeping my gauge below 2000 psi. I love it! Only wish I could put the psi gauge direclty by the gun, but the stupid hose is inside the gun handle may try to hack it latter on. As it is hard to watch the gauge and the metal expansion at the same time.  Thanks for all the ideas. Hopefully my headaches will help someone else.