TargetTalk

A forum to talk about Olympic style shooting, rifle or pistol, 10 meters to 50 meters, and whatever is in between. Hosted by Pilkguns.com
It is currently Sat Oct 21, 2017 5:13 am

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 52 posts ]  Go to page Previous  1, 2, 3
Author Message
PostPosted: Wed Mar 15, 2017 12:40 pm 
Offline

Joined: Thu Feb 23, 2017 12:01 pm
Posts: 15
deadeyedick wrote:
I have seen inside Air cylinders that have been refilled by scuba and pumps. Almost without exception the Air cylinders filled by scuba showed very little to no corrosion whereas the ones filled by hand pump developed corrosion more quickly and progressed rapidly.

I remember Ulrich Eichstadt ( Walther ) describing some of the cylinder interiors he has seen as resembling minefields the corrosion was so bad.

The interesting point to me was the increased rate of corrosion in cylinders hand pumped versus scuba filled.


Scuba pumps have pretty extensive moisture traps on them. Compressing air is condense a lot of moisture and the last thing you want while diving is water fouling your air supply somehow.


Top
 Profile  
 
PostPosted: Wed Mar 15, 2017 1:25 pm 
Offline

Joined: Wed Oct 14, 2009 12:44 pm
Posts: 687
Location: Costa Rica, Central America
hundert wrote:
I just calculated that the energy of the gas inside a fully filled cylinder at 200bar is 0.00359kg TNT equiv. A typical hand grenade has 0.0150kg TNT.

So, 3.59g vs 150g TNT

the blast wave of a typical hand grenade is very weak, it needs to be within a few inches from you to kill you, from one meter it's harmless (we're talking the blast wave, not the shrapnel). It will take your hands off if your're holding it.

if you don't have your hand wrapped around the cylinder, nothing will happen, with your hand something like 10 inches away from a cylinder which explodes nothing will happen.

Now, what will happen when it bursts while you're holding it, I don't know. I have an old cylinder which I could wrap with chicken wings and throw into fire :D I'd say some of the fingers will come off, will tear skin and tissue of your palm.


There are various outcomes you forgot to mention:

1. Mr. “Smarty Pants” comes out unscathed, but later on has some degree of permanent hearing loss. Lesson learned.

2. You get some shrapnel, become maimed/handicapped or a vegetable for life.

3. The Grim Reaper gives you no mercy, you’re six feet under, R.I.P...


Top
 Profile  
 
PostPosted: Wed Mar 15, 2017 1:42 pm 
Offline

Joined: Wed Oct 14, 2009 12:44 pm
Posts: 687
Location: Costa Rica, Central America
DFWdude wrote:
We'll be back to the stone ages shooting Walther LP53s. I have an LP53, and trust me, shooting one is not pretty or fun.


Dude, don't tell me you got one in the first place because you're a James Bond fan?


Top
 Profile  
 
PostPosted: Wed Mar 15, 2017 2:37 pm 
Offline

Joined: Tue Feb 18, 2014 3:10 pm
Posts: 184
kevinweiho wrote:
DFWdude wrote:
We'll be back to the stone ages shooting Walther LP53s. I have an LP53, and trust me, shooting one is not pretty or fun.
Dude, don't tell me you got one in the first place because you're a James Bond fan?

Well, I am both a former (NRA) Master Classification 10m AP shooter... and a James Bond fan.

Though chronologically, I became a James Bond fan in 1962, some twenty years before I bought my first airgun (1982).

Didn't buy the LP53 until last year. Complete with original box, and ALL accessories (extra sights, cocking ball, cleaning rod, instruction book, factory proof target, and rare barrel weight, etc). A collector's item, you know.

Be nice, now...

Image


Top
 Profile  
 
PostPosted: Sat Mar 18, 2017 5:38 am 
Offline

Joined: Wed Oct 14, 2009 12:44 pm
Posts: 687
Location: Costa Rica, Central America
Don’t worry, I was just joking around with you. Whoever gets or owns a LP53 is most likely a Bond fan.

I also like James Bond, that is the reason why I own a Walther PPK, but I don’t have it as my primary CCW.

You’re smart in snagging the LP53 with all the goodies. I bet it’s a safe queen, and will continue to appreciate in value over the years.


Top
 Profile  
 
PostPosted: Wed Jun 14, 2017 8:37 am 
Offline

Joined: Fri Aug 19, 2016 3:21 pm
Posts: 11
Regarding hand pumping: I always frown every time I use my hand pump because I know that moisture is moving into my bottle or cylinder. I usually fill as much as possible with my 4500 psi carbon fiber bottle that I have filled at the local paintball park. I make up the remaining pressure with my hand pump. I pump only indoors in air conditioned spaces to minimize moisture entrainment, and I'm still not comfortable!


Top
 Profile  
 
PostPosted: Wed Jun 14, 2017 1:26 pm 
Offline

Joined: Sat Nov 15, 2008 4:20 pm
Posts: 5019
Location: Scottsdale AZ
Like bad sex; if it doesn't feel good, you're doing it wrong.


Top
 Profile  
 
PostPosted: Thu Jun 15, 2017 9:36 pm 
Offline

Joined: Thu Oct 28, 2010 10:57 pm
Posts: 49
Location: Washington State
Steyr Air pistol Cylinders are definetly rebuidable
I've rebuilt 2 1996 painted versions "someone on this thread thought they were anodized" & installed gauges vs their old belville washer indicator gimmick that always leaked !
Mine were shiny new when I opened them up... sent each one back to Don Nygord at least twice... always leaking ?
They're better than new & clocked with the writing at bottom dead center ! a bit of effort, but not too bad.


Top
 Profile  
 
PostPosted: Mon Jun 19, 2017 9:57 pm 
Offline
User avatar

Joined: Sun Mar 30, 2014 12:09 pm
Posts: 455
Aluminum is a very interesting metal, but it's structure WILL eventually fail from the constant stretching from pressure. Threads on tanks and cylinders also wear away every time they're threaded into a pump or gun.

Cylinders are ticking time bombs if you really think about them. When they let go, it's catastrophic. Not like a hydraulic failure.

I support the 10 year rule, because on the very chance one blows up it'll take a lot of blood with it. They can become very dangerous if damaged or carelessly used. That being said, use them properly and you'll have no issues. Most out there will probably last 25+ years, but eventually they will either crack once the material work gardens from expansion.

They do expand quite a bit when filled, by several thousandths of an inch.


Top
 Profile  
 
PostPosted: Tue Jun 20, 2017 4:56 am 
Offline

Joined: Tue Mar 25, 2008 4:26 am
Posts: 693
Location: Australia
If anyone thinks "Shiny" = "OK" here is what a fatigue crack in aluminium looks like

Image


Top
 Profile  
 
PostPosted: Tue Jun 20, 2017 8:18 am 
Offline

Joined: Sat Sep 04, 2004 6:04 pm
Posts: 1435
Location: Massachusetts
Andre wrote:
Aluminum is a very interesting metal, but it's structure WILL eventually fail from the constant stretching from pressure. Threads on tanks and cylinders also wear away every time they're threaded into a pump or gun.

Cylinders are ticking time bombs if you really think about them. When they let go, it's catastrophic. Not like a hydraulic failure.

I support the 10 year rule, because on the very chance one blows up it'll take a lot of blood with it. They can become very dangerous if damaged or carelessly used. That being said, use them properly and you'll have no issues. Most out there will probably last 25+ years, but eventually they will either crack once the material work gardens from expansion.

They do expand quite a bit when filled, by several thousandths of an inch.

Sorry, but a properly designed and maintained aluminum air pistol cylinder is NOT a "ticking time bomb," and the 10 year limit is entirely an artificial one. For proof of the latter statement, consider that many manufacturers (Hammerli & Morini for certain) had no problem putting a 20 year limit on their cylinders until the bureaucrats came along. The old Hammerli 480K cylinders (rated for 20 years) were sort of fat & bulbous. They have a much greater internal surface area (resulting in greater forces) than any of the modern skinny cylinders.

If the stress on the aluminum is kept below a certain limit, the cycle life is effectively infinite:

Image

I don't know how they are designing them, but as an engineer, I wouldn't exceed that limit without a very good reason. For air pistol, I can't think of one that would require anything but an infinite service life. If it turns out that makes them too heavy, I would assume a full pressure cycle once a day for 20 years. That is still less than 10^4 cycles. You could more than double the stress and still stay way below the fatigue limit.

I'm OK with replacing my cylinders after 20 years, just to be safe. It's when the bureaucrats stepped in & suddenly decided to cut the service life in half that I get more than a bit ticked off. Spouting nonsense about "ticking time bombs" doesn't help. There are plenty of nitwits out there who will quote you as proof that air guns are inherently dangerous to life & limb as an excuse to eliminate current & future shooting programs.


Top
 Profile  
 
PostPosted: Tue Jun 20, 2017 8:31 am 
Offline

Joined: Tue Feb 18, 2014 3:10 pm
Posts: 184
Not to mention that the pressure cycles of bulk-filled CO2 cylinders are far less (800psi - 1000psi) than compressed air.

I suppose it's too much to expect that this thread, clearly titled "Aluminum CO2 Cylinder" could remain focused on CO2. At least the continuing debate regarding the PCP use, and completely arbitrary rules designed more to sell cylinders than observe an overwhelming abundance of safety precaution, provide some comic relief while keeping this thread alive. Thanks.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 52 posts ]  Go to page Previous  1, 2, 3

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: Bing [Bot] and 6 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group