<<— What Happened???? An Airgun Valve Mystery —&a
Went to the range today to shoot my 9 mm / .357 bigbore homebuilt airgun.
I have shot This .357 airgun over 1000 times.
At the range, I would shoot a 5 shot group, refill (from a 4500 psi carbon fiber tank) and shoot another 5 shot group. I repeated this at least 10 times.
Was filling the tank for the eleventh time, shut off the fill tank valve at 3100 PSI, and noticed an air leak from the filler blead valve. Tried to close the blead valve tighter and it would not seal. Decided to open the valve and it would not stop venting (I was bleading down the whole tank, like the tank valve did not seal.)
After it blead down, I unscrewed the tank from the filler.
THE TANK WAS HOT ! – much hotter than from a normal fill.
THE VALVE STEM FELL OUT IN MY HAND!
Also, I noticed THE DELREN VALVE SEAT WAS GONE!
It was not in the tank.
It was not in the filler.
It could not have gone down the barrel, because it was connected to the filler. IT WAS JUST GONE!
On close examination, the 6-32 screw, that the plastic valve seat was mounted on, shows some discoloration (blue color) .
CAN YOU FIGURE IT OUT? WHAT HAPPENED?
WHERE DID THE WHITE PLASTIC SEAT GO??
I know what happened (I think).
MARK
THE FILLER
THE VALVE ON THE LEFT SHOWS THE WHITE DURLEN SEAT
THE VALVE ON THE RIGHT SHOWS THE VALVE STEM WITH MISSING DURLEN SEAT. IT SHOULD BE ON THE 6-32 SCREW IN THE TOP OF THE VALVE STEM
CLOSE UP OF VALVE STEM WITH MISSING WHITE PLASTIC SEAT – SEE THE DISCOLORATION ON THE 6-32 SCREW
All Replies
RiffRaff:
That makes a lotta sense.
If the first shot after the Hopps #9 cleaning, could have blown back oil into the valve stem area. It could happen if the valve closed before the bullet exited the bore. Then pressure in the barrel pushes air & oil backwards and exits in the clearence between the valve stem and the valve body.
Then that oil gets pushed into the seat area when the tank was filled.
But, how do I know, for sure??
I am a little “gun shy” now.
I had a close call, that could have blown my head off.
I will be carefull to fill slowly, so as to not generate excess heat.
But is that enough?
What is a “PCP friendly oil”??
Yes, I was filling from 4300 psi.
Tomorrow, I’ll do more research on valve seat materials that are recommended for oxygen service. That may give an increased level of safety. I know that will not mitigate any oil problems, but it may not have been oil that caused the problem.
Mark
I did clean the bore with Hopps #9 cleaner, just prior to going to the range. The tank was not even mounted to the gun when I cleaned it.
Mark
If you didnt mop out the bore with a PCP freindly oil afterward, this is probably your culprit. You more than likely dieseled back into your valve, and the rust/oil from fingers/blowback residue caused ignition.
You are running your tanks to 4500psi right? That high of pressure with ANY volalile substance could cause what you described. If the Hoppes blew back into your valve during your first few shots, the pressure in your tank would cause it to ignite, burning up your valvestem and seal in the process.
I wonder how much it takes??
If I assembled the valve with oily hands, would that be enough to initiate the fire????
Mark
I wouldn’t think so? Might wipe some cutting oil on something clean and try to ignite it with heat from the edge of a flame.
You know, I always have oily hands (cutting oil for the lathe).
I wonder how much it takes??
If I assembled the valve with oily hands, would that be enough to initiate the fire????
Mark
About 20 %
The rest is nitrogen 😀
Mark
Too much oxygen in the air up there? 🙂
A quote from a professional valve company (not airgun valves):
Delrin must not be used!!!!
Doing more research….
Mark
airtight_python:
I just blew out half of the exact same CF tank I was filling from, unto the white paper.
Cant see any oil.
I’am gonna try lighting up some of that delren, and see how it burns.
Mark
airtight_python:
I just did the same, A blowtorch will not ignite the silicone grease.
My silicone grease is in a squeeze tube. It is a very old tube, looks like it is 10 to 15 years old.
I just blew A LOT of air, from my compressor onto a white sheet of paper. I could not see any oil.
I did clean the bore with Hopps #9 cleaner, just prior to going to the range. The tank was not even mounted to the gun when I cleaned it.
Mark
I also tried my silicone grease. It will not ignite either.
I just tried to ignite some silicone. What I have is not aerosol but a pump spray container. It will not ignite and in fact is a decent insulator for the wood I tried to burn it on.
If you have aerosol silicone can you might try spraying some, waiting a minute, and trying to ignite it.
My best guess would be that oil (whether compressor or gun cleaner) got in there and heat from pressurizing caused a small flame, igniting the delrin and burning it up.
If you used an aerosol spray silicone would it be possible that the carrier my have ignited? I don’t know. Just throwing an idea out there.
Thanks Airtight_P :
I did notice there was very, very light rust around the hole where the seal sits.
Could this rust be the source of ignition???
Maybe oil didnt cause this???
I dont have answers, so I cant use any of my guns till this is cleared up.
Mark
I found some interesting information on Delrin in an MSDS. I supposed wear could have worked up a dust…
I don’t know how it would have gotten that hot though. 😯
Flammable Properties
Flash Point : Not Applicable
“Delrin” dust cloud ignition temperature is 440 degrees C (824
degrees F).
Like most organic materials in powder form, dust generated from
this product may form a flammable dust-air mixture. Potential for
a dust explosion may exist. Minimize the generation and
accumulation of dust. Keep away from sources of ignition.
Burns with invisible flame. Hazardous gases/vapors produced in
fire are carbon monoxide, formaldehyde, hydrogen fluoride (HF),
and, carbonyl fluoride.
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I’ve heard the claim that EEZOX is not flammable.
When I run a lighter over a puddle, it will not ignite, but the flame from the lighter gets bigger. I assume that’s the carrier evaporating and burning.
This EEZOX is good shit IMO. One of the best rust protectants, cleaner, drying lubricant all in one. Smells good too. 🙂