Shoebox not going past 1,100 PSI? ***8/1 UPDATE***

"

Dollars for donuts you got a leaking valve!

With a thing working that slow it only takes a mouse whisker to deter the operation completly!"

So, the only valves that I can see are the check valves. Is that the valve you're talking about? I replaced the 'O'-Rings on them when I rebuilt the Shoebox. Do you still think that's the issue?

I soaped every crevice and don't see any leaks. Maybe I'll try that again.

Thanks!

mike

"That is what happens to mine when one of the orings on the high pressure cylinder starts to leak. I would look for a problem there, maybe a ding in the oring, some foreign material or maybe something else interefering with the seals"

Per your suggestion, I went back in and gave it another go. All looked good on the small piston side, but I went ahead and replaced the 'O'-Rings while it was open. I'm getting REALLY good at disassembly and reassembly now (silver lining?)!

Anyway, ran it for a few and the pressure came up slightly higher, but I could faintly hear a leak as I shut the Shoebox off (couldn't hear it below 1,100 PSI, but at 1,300 PSI, YES). So I cracked open the tank that I was connected to and soaped everything. It's the small brass fitting in the back of the block that is leaking. I assume that brass part is an overpressure port? Does anyone know where I can find another??

Is there something special about reinstalling a replacement? I had removed it when I initially couldn't find a leak and reinstalled it. Perhaps that's why it's leaking now? It's very tight. Instead of disassembling the entire block (again!), I am thinking of simply drilling a hole large enough to get a socket in there for removal and replacement. See any issues with that line of thought?

Thanks again for all of the great suggestions!

mike

BTB --=--

Thanks a BUNCH for the link and info on the burst disc fitting, much appreciated.

mike

So, the saga....

A buddy had an old Shoebox that had been cannibalized yet still contained the burst disc. He was kind enough to loan me the disc while I purchased one.

Drilled a .75" diameter hole through the back of the unit in line with the burst disc (luckily, it's JUST below the large pulley cog) so I didn't need to disassemble and readjust everything, and removed the bad one, replacing with the one my buddy had. Turned on the unit and it wouldn't go past 800PSI....DANG!

I bled the hose a couple of times without any luck in getting past 800PSI. After running it to 800PSI again, I turned on the tank valve that was connected to the compressor while it was running (I was only trying to fill the connector hose as a test) and the gauge shot up to 2,500PSI and started to move up from there. I'm assuming that it needed some back pressure to work against the check valves initially. After turning everything off, I bled the pressure from the hose dropping it to zero. Turned on the compressor and bingo, ran up to 4,600PSI where I had set the auto-shut-off before the issue and shut itself off. Took about a minute.

Lesson learned: If compressor pressure doesn't initially move the gauge, try backpressure from the tank to see if that helps in seating the check valves. Just sharing my findings in case it helps someone else.

Thanks again for all of your valued replies, much appreciated!

mike

So, I have searched for a burst disc replacement but seem to only find 3/8" diameter thread size (IF thread size is shown at all?). Therefore, my assumption is that the thread diameter is 3/8" but what kind of threads are these?

BTB linked a possible, but the thread appear to be of different spacing/pitch as they don't look like the one on my desk right now.

Per BTB: Here's an example – https://www.amazon.com/Pure-Energy-Bottle-Burst-Disk/dp/B009DDBRBG

Any help please!!

mike

Again, BTB, I thank you for the follow up on the burst disc information!

MUCH appreciated!

mike