Did I make a big mistake? I bought a Yong Heng compressor from China!!

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"fpgt72"If there is hesitation on startup, there is usually already pressure in the system. You can't open your gun/bottle/whatever and have that pressure hit the compressor....it will not start. you need to have no pressure into the compressor before starting it.
This would be a good test for the other poster.....see if it will power up and make air with nothing on the output....the compressor will basically free wheel.
Keep us updated.
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Thank you. With open bleed valves before startup there has been no incidence of hesitation on startup. As for the guage, it appears the oring I chose for the block output to microbore was, in fact, constricting output. It was either twisted or crushed in some way enough to block free flow of air out of the block. I was using a BLACK o-ring that is softer than the greens. I tried a small green ( which I do not think is the intended one for this spot because it slips in too easy). However the green is more rigid and does allow the free flow of air with no leakage, so green it is unless we have a poster with a better idea. 
 
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Just FYI, on some of the Chinese compressors, the block output to micro bore hose connection is NOT a PT (pipe thread) connection and requires a "dowdy seal (bonded washer)", not an O-ring. If there is not machined groove for the O-ring to seat, it will eventually blow out. You are probably seating a flat metal surface to another flat metal surface, which requries a "captured" O-ring, They look like this, and there are probably some included in the spare parts package of your compressor.

6a0a0b1deb1dad13767d045df5ccd80d.jpg
 
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I missed the part about it popping the ground fault.....yea, that is not due to too much draw.....It is easy to blame the new thing plugged in, but I would suggest pulling everything on that circuit then go back and one at a time plug them in.....if this outlet has not been used before it could be an issue with that outlet. If possible if this is an outlet that is not used or had a 2 prong device connected, I would try another outlet just for good measure. These little compressors do pull a bit of amps....mine drew I think 8-9 amps....that is a chunk on a normal 15 amp house circuit.....if it is on with your fridge, or microwave it may just be too much.

Ground fault is really in a nutshell a trip for a quick trip to the ground side, it is not an overload protector. I have seen outlets that are wet/ not wired correct, damaged by critters trip when they are used, and be just fine other times or with low draw devices.

There are a few things to check as to why the thing is tripping.
 
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"geelee"i bought one of those yong heng compressors also. the one i bought was the 110 volt with auto cutoff. so i opened the box took out the compressor, followed the instructions I found on you tube. And it didn't come on. i doubled checked everything tried again and nothing. I tried to contact the seller and no luck there. I have sent several e-mails but no reply. so i took the compressor to an electric motor repair place, they looked it over and determined that the motor was ok. so something in the compressor must be stopping the motor. I knew what i was getting into when I bought it, in other words, i knew there was a good chance it might not work , even though I have read a lot of good reviews on the internet about these compressors. i know I am not going to send it back so next week maybe I will take it apart and see what I can find. also the water pump that came with it doesn't work. So maybe I just got unlucky with this thing and got a bad one. For the price I don't feel to bad about it, and who knows maybe I will hear from aliexpress about this thing. I'm pretty handy with a wrench maybe I can get it to work. but if not I guess i will start saving up again for one of those more expensive models. I hope you have better luck with yours then I had with mine.
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Have you had a chance to take some pics of the innerds of your compressor.....I would really like to help you out.

or if you are not comfortable just post up a quick video and shoot us a link to it.....I think we can get you going.
 
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Hay....geelee, have you had a chance to take those pics of the innerds of your compressor, or post up a video.....anything to help point us in the correct direction.

I am interested in seeing what your issue is, see if it will freewheel, if you can hand turn the crank.

Also what kind of tests did the electric motor repair place do, I would be interested in seeing the internal numbers on your motors windings, I am at work, so I don't remember if it had a cap or not, if so what did it test out to be, brushes....all that jazz....the electric place should have told you all this info, and printed it out for you......this info can help the rest of us down the road if we have electrical issues with the motor on our compressors.
 
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Hi fpgt72,
I had the compressor completely apart yesterday (but didn't see these msgs until just now or would've taken pictures). Mine wouldn't turn over with 110V - bought the 220V version (accidentally) and the seller told me I could just use an adaptor and plug it in to 110V. That didn't work, so I plugged it into a step-up transformer and it still didn't crank. It would jump once then seize up. Finally pulled it apart yesterday and found that the 2nd stage piston had globs of graphite on it, which was binding that piston. Graphite was actually caked on around the 3 o-rings at the top. I cleaned the piston off as best I could but noticed that, while better, the crank was still difficult to turn by hand and definitely had "sticky" spots in the rotation. It seemed like the 1st stage cylinder wasn't an issue so I loosened the 2nd stage base (the water block) a bit and hand-cranked the piston up and down while gradually re-tightening the 2nd stage. That did the trick. While there is still some stickiness through the rotation, it's much reduced. The crank doesn't spin freely or anything, but it is much less effort to turn by hand. Now it turns over on 220V and pumps up to 200 bar (haven't dared go above that yet), but it still doesn't quite turn over on 110V. Probably need to go in there and re-lube the 2nd stage piston properly with graphite or molykote - I just wiped it off yesterday.

Incidentally, be a bit careful when sealing up the front of the crankcase - yesterday I wasn't careful enough and didn't realize the rubber face gasket seats into a lip around the perimeter. I had pinched it in the right hand bottom corner by the screw and when I turned it on, oil blew out the bottom of the seal and went everywhere. But it did turn over and pump finally.

Finally, there is a big capacitor in line with the motor. - if I take off the cover again, I'll get the specs for you.
 
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The second stage "pencil" piston with the four semi metallic rings should not be lubricated at all. ZERO lube for that section of the compressor. You can buy replacement rings for that and the first stage on eBay or AliExpress. Basically all repair parts are available online for those compressors. If its a 220vac motor, then it won't work on 115vac, and vice versa. It seems you have figured out how to connect it to 220vac, which is something you'll probably have to live with. The 220vac clothes dryer connection in most houses will work. 
 
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@bobad - thanks for the warning, I appreciate it. Yes, I was wondering if all the graphite I saw might have also partially been the result of dieseling of whatever grease they may have put on that piston. I didn't regrease at all, just cleaned off the graphite (though my hands had a film of silicone oil on them). 

Also, I ended up running a quick test to monitor the rate of T increase on both the stainless tube and the water for my YH. Here's the data. Some details: I used some silicone tape to attach the type K thermocouple directly to the stainless tube. I used the one that goes between the water block and the output stage (the shorter, thicker tube that runs vertically like a coffee mug handle). Oh, I'll attach a pic to show how/where it was located.
344659cecc05dbe785f4e5520d64c9da.jpg

36f7ecb8dff9f2d5bc6f4046e171415f.jpg


It looks like the tube temperature will top out maybe around 320F give or take, so really no worries about thermal cycling or even high temperature derating of the tube. I suppose the exp't should really be run during an actual fill and for much longer to be sure. I brought my YH to work to test it out so right now have access to the tools and equipment... if there is any other measurement that might be useful to do, let me know. We're supposed to have a big storm tonight and tomorrow, so no shooting. Might as well try and learn something (assuming I can actually get to work tomorrow).
 
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Hi Centercut,
Thanks for that info! Glad I didn't try and lube it when I cleaned it out earlier. Like I said, lots of carbon all over it when I first removed it - was assuming it was a graphite powder being used as an anti-seize compound. Anyway, it's running fine on 220V now using a step-up transformer. And yes, the seller told me to just use a plug adapter, which I didn't really believe. But he sent me one free so I tried it (and of course, it didn't work).
 
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Prfssrlee, you're welcome. I've been concerned about that temperature of the tubing also. The temperature you measured is the tubing between the output of the first stage and the input of the second stage. I don't think the second stage adds much more heat, but you may want to check that also. I think that the first stage does more "work" than the second stage, and gets hotter than the second stage. It would be beneficial to measure those two temperatures, in addition to the cylinder water jacket temperature (on the unit) while filling a tank from say 3000 to 4500 psi, which is what we normally use these compressors for. I am working the two cylinder Tuxing project, you may have seen my posts in this forum. I want to try aluminum heat sink fins on the tubing first to second stage, and then on the outlet valve block I am going to install two Thermoelectric Cooling Plates to try and lower the outlet air temperature (and hence lower the dew point). It appears the single models measure the first stage water jacket, while the double cylinder models measure the second stage water jacket. Keep up the good work, +1 to you...
Mike
 
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"prfssrlee"Hi fpgt72,
I had the compressor completely apart yesterday (but didn't see these msgs until just now or would've taken pictures). Mine wouldn't turn over with 110V - bought the 220V version (accidentally) and the seller told me I could just use an adaptor and plug it in to 110V. That didn't work, so I plugged it into a step-up transformer and it still didn't crank. It would jump once then seize up. Finally pulled it apart yesterday and found that the 2nd stage piston had globs of graphite on it, which was binding that piston. Graphite was actually caked on around the 3 o-rings at the top. I cleaned the piston off as best I could but noticed that, while better, the crank was still difficult to turn by hand and definitely had "sticky" spots in the rotation. It seemed like the 1st stage cylinder wasn't an issue so I loosened the 2nd stage base (the water block) a bit and hand-cranked the piston up and down while gradually re-tightening the 2nd stage. That did the trick. While there is still some stickiness through the rotation, it's much reduced. The crank doesn't spin freely or anything, but it is much less effort to turn by hand. Now it turns over on 220V and pumps up to 200 bar (haven't dared go above that yet), but it still doesn't quite turn over on 110V. Probably need to go in there and re-lube the 2nd stage piston properly with graphite or molykote - I just wiped it off yesterday.
Incidentally, be a bit careful when sealing up the front of the crankcase - yesterday I wasn't careful enough and didn't realize the rubber face gasket seats into a lip around the perimeter. I had pinched it in the right hand bottom corner by the screw and when I turned it on, oil blew out the bottom of the seal and went everywhere. But it did turn over and pump finally.
Finally, there is a big capacitor in line with the motor. - if I take off the cover again, I'll get the specs for you.
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Thank you so much....take care with that cap....they can be dangerous.....depending on it...VERY DANGEROUS.

I am not sure I would buy 220 running on 110....I don't know much about electric motors but did stay at a holiday inn once.....the two units should not be the same motor.

thanks again.
 
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"bobad"@prfssrlee,
Be careful with lube, especially in any significant amounts. I'm guessing the 2nd stage has enough pressure to diesel with some lubes. In fact, that could be why it has problems turning over. I would think minuscule amounts of the recommended grease or oil for reassembly are all that's needed.
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+1.....remember how hot those lines are coming out....and the temp in the head....Graphite is IMHO perfect for this application..
 
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"prfssrlee"@bobad - thanks for the warning, I appreciate it. Yes, I was wondering if all the graphite I saw might have also partially been the result of dieseling of whatever grease they may have put on that piston. I didn't regrease at all, just cleaned off the graphite (though my hands had a film of silicone oil on them). 
Also, I ended up running a quick test to monitor the rate of T increase on both the stainless tube and the water for my YH. Here's the data. Some details: I used some silicone tape to attach the type K thermocouple directly to the stainless tube. I used the one that goes between the water block and the output stage (the shorter, thicker tube that runs vertically like a coffee mug handle). Oh, I'll attach a pic to show how/where it was located.
344659cecc05dbe785f4e5520d64c9da.jpg

36f7ecb8dff9f2d5bc6f4046e171415f.jpg

It looks like the tube temperature will top out maybe around 320F give or take, so really no worries about thermal cycling or even high temperature derating of the tube. I suppose the exp't should really be run during an actual fill and for much longer to be sure. I brought my YH to work to test it out so right now have access to the tools and equipment... if there is any other measurement that might be useful to do, let me know. We're supposed to have a big storm tonight and tomorrow, so no shooting. Might as well try and learn something (assuming I can actually get to work tomorrow).
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I should have made just one post...oh well.

I would be interested in your amp draw as well....mine pulled only 8 amps all the way through the run cycle....no spike at startup that my stuff could detect....i admit my stuff is more home then a real testing setup....but it is interesting.

I am not asking you to do this, but it would be good to get numbers on as much stuff as we can.....I am not going to take mine down till it needs it but when I do I plan on pulling numbers off everything I can think of to see just how these suckers work and what makes them work....from o-rings to the winding
 
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Hi Mike, Yes, you are right - I can't count, apparently. The tube I measured is between the 1st stage and the 2nd as you say. And I agree that it's the 1st stage that's doing the most work on the air. I re-ran the same test as before but monitored both that same location and the 2nd stage output tube. I'll put up a plot later but the result is that the 2nd stage tube remains at a lower temperature - it's probably a smaller bore and it's longer, so there is a much larger SA:Volume ratio which may be what's keeping it at a lower temperature.

@fpgt72- I do have a 100A Rogowski coil here at work but unfortunately it doesn't fit around the 220V plug. I don't really want to cut and splice the cord, but maybe I can find an older spare cord lying around to do that and put a standard 220V-EU plug on the end of it. It would be interesting to see what the current draw looks like over time.

Also, all these experiments are to an unattached microbore hose because my cylinder is somewhere between here and the AceCare factory in China. I actually got the valve and PCP fill adapter for the tank yesterday from FedEx IE, so the tank can't be that far behind (hopefully). Everything was ordered at the same time, but the YH came first and that's why I've been doing these experiments instead of actually filling a tank.
 
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Here's the plot where I added a thermocouple to the 2nd stage output tube as well. Notice it never rises above ~210F - I think that's because it actually can see 1 atmosphere at the end of the microbore hose (ie, where it just vents). So in this configuration there isn't nearly as much work being done on the gas in the 2nd stage and it's able to dump all its heat out into the room as it expels the compressed air (as Centercut expected). So I think the bottom line is that I'll need to do this experiment with a fixed final volume (ie, a cylinder or reservoir attached). Once the 6.8L tank I ordered arrives... Also notice that the temperature readings bounced around a bit, especially on the 2nd stage output - that's probably the accuracy of the thermocouple readings (say +/-5F) - they are notoriously susceptible to electrical and mechanical noise, drift and other errors (and I didn't do anything except tape them to the tube). 

dacd2206e1c5ef235d98a8d206df1c35.jpg
 
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