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Breitling888
06-07-2011, 08:20 PM
Hello,

I have a new Shoebox with about 15-20 hours on it. Typically I turn on the shoebox with the valve on my tank closed and wait for the pressure to get up to 4000 psi before I open the valve.

Today I turned on the shoebox (with the same procedure of waiting to open the valve) and it wouldn't go above 2500 psi. I turned off the shoebox to see if there was a leak. I could hear a slight leak and tried to determine where it was coming from. As the pressure dropped, I could barely hear the leak anymore. Before I got the soapy water ready, I just opened the valve on my tank to pressurize the line and the air was rushing out of the block. Then a strange thing happened. As the pressure in the line went up, the leak stopped. I don't know what happened, but maybe the o-ring got blown back into place by the high pressure air going in the opposite direction.

I don't know if this actually fixed the problem for good or if it will even last for one fill. I am currently trying to fill my 17 cubic foot CF tank from 3500psi to 4500psi.

Any thoughts or do I just have to rebuild the block as others have done?

Thanks,

Greg

TomKaye
06-07-2011, 11:58 PM
It was probably the vent oring. That will re-seat when you blow air backwards through the line. I wouldn't worry about it unless it happens again.

Tom

Breitling888
06-08-2011, 11:26 AM
Hi Tom,

Thanks for the quick reply. Well my CF tank made it to 4500 psi, so the leak problem is solved for now. If it really was the vent o-ring that got un-seated (and then re-seated when I forced air from my CF tank back towards the Shoebox), how do I prevent it from un-seating again?

Regards,

Greg

TomKaye
06-08-2011, 04:49 PM
It just happens once and a while. The best way is to get a hose from Joe B that has a vent built into it and leave the Shoebox one alone.

Tom

Breitling888
06-08-2011, 07:27 PM
Hi Tom,

I was using the vent on my CF tank (rather than the vent on the Shoebox) for all of my previous fills, so I was probably already doing something similar to what you suggested. Is it possible that this procedure contributes to the un-seating of the o-ring rather than helps it stay seated? If the o-ring has some play or ability to get unseated in the direction of normal flow, wouldn't venting on the hose/tank side have a tendency to un-seat the o-ring as the pressure releases in the direction of normal flow as it is being vented? Wouldn't it be better if I used the Shoebox vent and allowed the pressure to vent in the opposite direction of normal flow (assuming that this o-ring is before the Shoebox vent) to help the o-ring stay seated?

I'm sorry to take so much of your time towards a problem that seems to have been resolved, but I think that it would be helpful to other users if they encounter this problem in the future. Initially I thought that I had the cut o-ring problem in the block that had been reported previously and thought that I was going to have to go through the rebuild. The problem that I had was much easier to solve and it might be helpful for other users to try to run high pressure air (assuming that they have 3000 psi or more left in the tank) in the reverse direction before they try to rebuild the block.

I really like your Shoebox compressor so far and I can say this even though I have access to a dive shop less than 2 miles away. It is so convenient to go to my workshop and just top off my CF tanks. Plus I get a true 4500 psi from the Shoebox, where I only get about 4100 psi from the dive shop after everything has cooled down.

Thanks Again,

Greg

TomKaye
06-08-2011, 10:56 PM
Without knowing exactly which oring was leaking its hard to say what the right procedure would be in this case. tk

Breitling888
06-20-2011, 08:56 PM
Hi Tom,
Ok, three more runs since the first leak. Two times the block was leaking and I had to send air from the CF tank backwards to reseat the o-ring (just like the first time it leaked). Today I tried the same thing and no luck this time. I tried the soapy solution to determine where the leak is coming from and it is at the base of the block. Please tell me what I need to do to fix this problem.

Thanks,

Greg

TomKaye
06-21-2011, 03:20 AM
You need to email me you phone number at info@shoeboxcompressor.com and I will call you. Please bear with us as we had to evacuate due to the fires in AZ.

Thanks
Tom

Breitling888
06-22-2011, 05:50 PM
Hi Tom,

Thanks for calling this morning and guiding me on changing the o-ring in the block. I got the chain back on and I'm currently running the Shoebox on my little 17cf tank. It's up around 4000psi right now, so the new o-ring seems to be doing its job. I also looked more closely at the o-ring that I removed from the block and noticed that there was a small cut all the way around the perimeter of the o-ring. As I mentioned on the phone, I am going to order two more cylinder rebuild kits. If you don't mind, could you add in a couple of the stronger o-rings for the block as well?

Thanks Again,

Greg