Filler plugs

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Re: Filler plugs

Postby Lightning22 on Wed Sep 02, 2009 3:49 pm

mamcrackin wrote:I pulled one of the orings off of my fill plug because, I had a leak in the fill port
and it pretty much pressurized the fill plug between the orings and made it really
hard to get out...1 oring on the end works fine and it doesn't fall out...



Someone is going to have to explain the physics of this to me as it simply doesn't make sense to me.
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Re: Filler plugs

Postby ian johnstone on Wed Sep 02, 2009 4:07 pm

Rich, there's a chap making a type of filler plug :roll: over in the States, I think Jeff /mamcrackin has one of those.

They're like the old webley raider plugs with a head that sits proud of the cylinder body.

I think all he has achieved is an easily removable plug ... & a slowly deflating cylinder :lol: .
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Re: Filler plugs

Postby Lightning22 on Sun Sep 06, 2009 11:54 am

Hi Ian,

What I mean is the physics behind how compressed air apparently manages to lock a bung in place.

My understanding is that a gas (air in this case) will exert an equal pressure within a vessel (the space between the o-rings) and in doing so the plug stays in exactly the same central position as it would if the space was at atmospheric pressure. Am I right so far?

Assuming I'm correct the plug won't be forced against the walls of the fill port and won't be locked in that way, likewise as you slide the plug out of the fill port the space between the 0-rings remains constant until one ring breaks the edge and there is pressure loss. Therefore, as you are not compressing the gas there is no increase in pressure caused by movement so movement won't be restricted.

Well, that's my understanding anyway.

My suggestions regarding sticking plugs would be,

1). Get your cylinder repaired before you have a 200bar leak.
2). Use a decent silicone grease on the o-rings.

Rich
;)
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Re: Filler plugs

Postby requoil on Mon Sep 07, 2009 2:14 pm

Lightning22 wrote:Hi Ian,

What I mean is the physics behind how compressed air apparently manages to lock a bung in place.

My understanding is that a gas (air in this case) will exert an equal pressure within a vessel (the space between the o-rings) and in doing so the plug stays in exactly the same central position as it would if the space was at atmospheric pressure. Am I right so far?

Assuming I'm correct the plug won't be forced against the walls of the fill port and won't be locked in that way, likewise as you slide the plug out of the fill port the space between the 0-rings remains constant until one ring breaks the edge and there is pressure loss. Therefore, as you are not compressing the gas there is no increase in pressure caused by movement so movement won't be restricted.

Well, that's my understanding anyway.

My suggestions regarding sticking plugs would be,

1). Get your cylinder repaired before you have a 200bar leak.
2). Use a decent silicone grease on the o-rings.

Rich
;)


The same principle applies when filling the cylinder. I filled my Hornet once when my mind was on something completely different, (Not recommended!) Filler probe in, open dive bottle valve, fill to desired pressure, close dive bottle valve, then forget to bleed the air line, remove filler with a bang as the residual 232 bar of air escapes, damaging the fill probe O rings. So yes, there is no great force holding the fill probe or blank in place even if a leaking fill valve has pressurised the fill blank O ring space.
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Re: Filler plugs

Postby Lightning22 on Mon Sep 07, 2009 9:43 pm

requoil wrote:The same principle applies when filling the cylinder. I filled my Hornet once when my mind was on something completely different, (Not recommended!) Filler probe in, open dive bottle valve, fill to desired pressure, close dive bottle valve, then forget to bleed the air line, remove filler with a bang as the residual 232 bar of air escapes, damaging the fill probe O rings. So yes, there is no great force holding the fill probe or blank in place even if a leaking fill valve has pressurised the fill blank O ring space.


So as I thought, though to be fair I've never been daft enough to find out that way..... ;)








Famous last words...
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Re: Filler plugs

Postby requoil on Mon Sep 07, 2009 11:58 pm

It certainly startled me. Filling becomes such a routine, you can lose sight of the obvious dangers when using such high air pressures.

YES, not one of my brightest moves.
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Re: Filler plugs

Postby ian johnstone on Tue Sep 08, 2009 8:52 am

I've done that in the past :( I think somebody came to the door just as I'd got 'er filled (doubly annoying as I'd seen a couple of Rats near the Chicken shed & wanted to get at 'em straight away) - yes it gave me a shock!!!

Not something you do twice (crossed fingers).
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Re: Filler plugs

Postby mamcrackin on Sun Sep 13, 2009 3:04 pm

UPDATE.....
Yes I did have a leak in the fill port valve but that was fixed before I posted
about the plug getting stuck....Here is my plug..
Image
When it is installed, if the fill port starts to leak it will pressurize between the 2
orings and make the plug impossible to remove without using pliers...So I took
one of the orings out of the groove and placed it against the head of the plug so
that it will still seal the fill probe port but can not get stuck if the fill port valve leaks again...
BSA Super Ten MkII .22
FX Cyclone .22
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AirForce Condor .22 Airhog 2,200psi regulated
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Theoben Rapid .22 in transit...
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Re: Filler plugs

Postby Gwildor on Tue Sep 15, 2009 6:17 pm

hi all ordred my filler plug off Lightning22 on sunday and it arrived this am (Tues), fits like a glove, looks well, and will keep the crap out. its delrin and looks like it was made for the vermmie, well happy :D :mrgreen: .
thanks to rich top man

graham
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Re: Filler plugs

Postby Lightning22 on Tue Sep 15, 2009 10:48 pm

Glad you like it Graham!

Rich
;)
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