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Impact leakage (pictures)

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SWEJaeger

SWEJaeger

Member
Oct 12, 2016
31
0
AC
What to do when the gun are leaking 10bar in 24 hours.



The leakage occurred after a regulator rebuild. Have had no problem with the gun for two years. Then one day suddenly empty and wont take any air, big leakage through the small hole on the block behind the safety lever. I think its the hole that depressurizes the "spring washers volume" in the regulator.

I made a regulator service, replacing all components. But after I have a small leakage of approx. 10 bars in 24 hours. Logical it is still the regulator unless I'm really unlucky and something else has failed at the same time.

Have opened it and re-assemble twice trying to keep it clean = same problem. Pretty sure I have not scratched anything becuse I did not even touch the surfaces.

Have tried GL4 leakage spray but the leakage is to small to detect where it comes from.

When unscrewing the air bottle the regulator hold the air approx 10 minutes before the regulator piston releases and all air blows out.It this normal or should it hold the air longer?

Something I don't like is that many of the orings gets a small small ditch right at the contact surface. Not possible to see with naked eye. But when looking through USB microscope its visible Starting to believe the surfaces are generally to coarse in the regulator cavity :(

1540455479_19400915685bd17c37a69f66.24125503_piston.jpg


1540455491_17759589955bd17c437dfc46.43473778_oring.jpg




Any suggestions?

David Sweden




 
I second the gauge leak I had an Airforce condor that had held air for years no problem. I got it out of my closet one day and the tank was empty. I started refilling it to see where the leak was and at 2000 psi the gauge lens poped off and hit me in the face. I am glad I had safety glasses on! And yes I did jump a little when the bang went off. I called Airforce and they sent me a gauge for free no shipping charge. M
 
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Funny thing about regs is that they actually need a non-mirror finish inside them. The lubricants used fill and seal those microscopic scratches, and without them all the lubricant becomes wiped off and the reg becomes sticky and unpredictable. Consistently achieving the correct level of finish inside a reg for optimal function is one of the challenges of building them. Just something to be aware of. 

As for 10 bar in 24 hours..... this is going to sound crazy, but have you filled it, left it for 24 hours, checked that it is 10 bar down, and then left it for another 24 hours and seen it lose another 10 bar? I as because, when I first got my Crown, I thought I had the same problem, as I'd lose 10 bar in the first 24 hours after a fill. It took me a while to figure out that it was because, when you pressurize the tank, the air heats up thus exerts more pressure. As it cools, you'll lose some pressure, and depending on your fill system that is often about 10 bar in the first 24 hours, but 0 bar after that (assuming your house stays a pretty constant temperature). 

I hope something in that was helpful. :) 
 
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All parts are new. FX sent me everything,housing, needle valve & piston all pre-assemblied.

The pictures above is from the old components. But I think I can make out the same ditch in the new orings after opening it up again.

Or at least I think I can see a hint of the ditch beginning to form.



Ditch = the small groove that goes all around the oring seen in the first picture

English is not my language, don't know if ditch is the proper word for it :)



The sad part it that I have access to almost any relevant equipment I want regarding this. I have two really expensive surface finish measuring machines on my office desk in front of me. And I really understand the result of the readings.

It would be really interesting to get Ra, Rvk and Rpk values of the inside of the regulator. But I have no extension pin to fit inside the hole :( 
 
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I just rebuilt my regulator. It took me almost an hour to get that blasted O-Ring (9x1.5mm) into the groove. I pressed the regulator post in, and reassembled the regulator. still leaked. Removed the regulator and went through the same procedure again. This time, I pressed much harder on the regulator post (Piston?) until it snapped past the 9x.15mm O-Ring. The first time, I never heard it pop, so I assume it wasn't in far enough the first time around. Once it popped in, the leaks stopped.

May not be your problem, but it was mine. Gun back to shooting consistently again. Good to be back at the range.
 
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I did not push very hard. I used a plastic drink straw.

But I think when screwing in the brass housing the housing will push the piston in the correct position.

and the smaller diameter of the piston, the rod part will go inside the housing.

Opened the regulator again yesterday and tried to clean the parts. Did not touch the piston but the other parts.

I think the leakage is a little bit less now. But I'm not sure yet.



Its very difficult to clean the parts 100%. When looking through a USB microscope I still see dust and small fibers.

And if I tried to wipe it of with a paper then I get particles of paper. Rag = small small fabric fibers.

I think I will bring the parts to work where we have a small ultrasonic washer. And then bag all the parts and threat them like its anthrax until I get home.

But I don't know how to be sure the inside of the cavity is super clean. Maybe one of those air spray cans for electronic will help.

By the way, that nasty inner cavity oring Ø9x1.5 mentioned above is missing in the STL CAD model everyone is using.

I think the new guns have replaced this oring with NBR90 a slightly harder oring than NBR 70. Maybe this is something to try as well.

1540541327_557673465bd2cb8f216906.22567101_regulator.jpg

 
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Problem solved. The rifle is now tight :)

Back to tuning for accuracy.

right now with reg.100bar 260mps ( 853fps) std. deviation 1.12 (3.7) :(

Click to expand...


What exactly was the problem?
Click to expand...


Not sure, didn't find anything. But when I opened up and reassembled third time it was tight. So must have been some small fiber or hair stuck between?

Or it could have been the manometer. More torque on the manometer this time.
 
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OT but now I know where the groove comes from.

Its a defect in the oring. Orings are made in a casting dye made of two halfs.

1541160783_11164375305bdc3f4f7d09f4.87165638_oring.png


The burrs that occur in the casting gap are deburred throug freezing the orings and tumbeling them together.

Rubber vulcanization makes the oring shrink some %. It shrinks more where the burrs where or something in the molecule structure around this burr

makes the shrinkage not symetric. This is why the groove are there.

So bigger part line from casting = bigger defect
 
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