What charge can you leave in a stored Airforce Gun ?

[Nomadic Pirate]

I'm looking into getting a Talon Pistol to use as my truck gun,...I was wasndering what king of pressure you can leave the gun to while stored in the veicle.

Thanks

[cactusrat]

I keep all my PCPs at full charge, two of them are Talon SSs. Some people just leave a couple of thousand in them. Always keep something in them to keep dirt out of them.

[aack73]

i keep my pcp fully charged too Manny. so far so good.

[TimmyMac1]

I'd store it at the low end of the pressure span you run so it is still good for a few shots but it isn't putting the valves at risk if the Car gets toasty sitting out in the Sun.
You can screw up about any seal if you put enuf heat/pressure to it so when trucking the pressure doesn't need to be topped but you don't know the toll for that bridge till you get off.
We thought it was OK to leave the Korean guns fully topped up but now we are finding out that was a bad idea.
Too much of any kinda stress for your toy is sorta a pointless test of how tough it is for the sake of exercising your wallet if you don't error on the side of Lower Pressure.
The upside is the system will live longer. No downside except you need to pump/charge before shooting rather than after. The downside to being careless is you may find oiut in 5 years that you lost the bet and you get to give me or AirForce some coin to freshen things up. No bigee as soft goods are just that(soft) and are expected to be consumables in the long run.
The question is how often to you want to swap out your seals.
The HiFlow valve of the Condor and Talon Pistol will need a 2000-3000 PSI operating range so I'd store it at 2500 in the truck and 2000 PSI for Long term storage or if the truck was going to get Hot. In Superhot conditions I'd take it down to 1000 PSI

[rsterne]

If you fill the gun to 2100 psi at room temp (70*F) and then heat it to 170*F the pressure will increase to 2496 psi.... I doubt your truck would get that hot inside.... so the pressure itself wouldn't be an issue.... Whether 2500 psi at hot truck temperatures could bother the seals I don't know.... but Delrin, as an example, has a "long term service temperature" of 185*F....

Bob

[MustangMike]

keep my disco when it was working lol at full charge so its ready to go for when i saw the infamous shed possum i have living under the shed in the backyard

[Nomadic Pirate]

OK, my Usual charge left on all my stored guns is 100 BAR, I was thinking to leave the Talon charged in the 150 BAR Neightbohood, that should give some leeway for the truck getting hot and still give a good power few shots.

[aack73]

you could always pump a little back in it if you need more than a couple.

[Nomadic Pirate]

She will be putting in mainly truck gun dutys, but now and again she'll be fully charged Too

[Ribbonstone]

Storing under full pressure won't cause the seals to disintegrate or promote leaking.

What it CAN produce is a gun that ends up shooting slower after long storage under full pressure.  The valve seal size, shape, and most important: material. even big gun makers don't make their own plastic...they buy it, so they rely on the quality of their suppliers.

So what can happen is that the valve is mashed by air pressure to a form fit to the valve stem seal seat.  SOME seals can get mashed too much, taking a set in that new shape (esp. if stored where it is warm).  IF they set in that shape, then velocity can be lower than expected.

Why? Because they have much more contact area and don't release as "clean" and they have become slightly wider, with a more irregular shape which can reduce air flow.

The AirForce valves I've seen have pretty large seals...but they are of something like black Delrin, and are quite tough.  I've not seen them take a set.  But the plastic is outsourced, and it is possible a poorer quality batch could be used.

So if you put one away under full pressure that was shooting 950fps, and months later find it shooting 835fps, its probably because the valve stem seal is in a new shape/with a much larger contact area to its seat.

[Bandit_46]

Manny,being here as long as I have,I've learned You and I think along the same lines when it comes to taking Care of our PCP's.
I have to add my .02 cents to this and say that I will take Tim's advise any day when it comes to my PCP's as he's been into them a long time,(and has many years knowledge) backing his comments up as well.

When it comes to my Korean's I will follow his Advise to the letter as being a journeyman for many years, as well as a licensed welder,I can tell you  that High Pressure's can Stress and Fatigue metals,so stressing an Oring with 3000 psi for extended periods, cannot do anything but cause them to Fail Prematurely.

For someone to say,Storing under full pressure won't cause the seals to disintegrate or promote leaking,with all due Respect,is like saying that, ''Dry Firing a Springer doesn't damage a Spring Gun'', when we all know better.

Advise is always Cheap,,But Good Advise is Priceless. JMHO,


Thanks

[aack73]

i'm not saying it will or won't damage. but if it goes a year or longer. i'm good. seals are cheap and i would likely take it apart for a good wipe down and inspection anyway. everybody situation is different. i'm likely to wind up at a friends house and we might want to shoot a bit. as soon as i get my fill hose from Tim i may take his advice as i will have a portable tank for quick and easy refilling. then it wouldn't matter. i only keep it "ready" because that is worth more to me than replacing seals/orings. or even the whole valve assembly for that matter. i'm sure the less stress it is under the better.  

i often get a "chance" coming in the driveway at the beginning and the end of the day. or maybe even at a friend or family members during the day as i drive alot.

[TimmyMac1]

When something takes 10-15 years to fail it is no big deal but I look at it from a preventative perspective. If you know it will happen why create the problem.
I know now that overcompression of exhaust valves is common in Korean guns that are left fully charged.
They have Enormous seats and porting and are the biggest area inside the seat of any gun I've worked on. Couple that with the fact that the exhaust seals are on the B-C durometer scale where the Stuff we use on smaller seats is (D-Scale 75-80 shore) which translates to about twice as hard. Twice as hard on half the area means the seal compression potential is not extreme on the hard small seals but pushing the limits on large seats/soft seals.
The weakest link in the Korean system is the oring seal on the shaft of the Gauge plunger rod. This will always fail first as the seal is going to extrude between the shaft and the gauge body. This is your pressure relief valve and indicates a gun has spent time in full charge mode. With any luck it blew before the exhaust seal got significantly overcompressed. The only way to know is to do a full teardown but all the orings need to be changed out for 70 durometers anyway so your in there to evaluate and get the original stuff out of there.
The weak link I always upgrade to urethane 90 duormeter so we never have an issue again. Now the problem is you have no pressure relief as the weak link has been eliminated and now the weak link is the exhaust seal and the customers willingness to push the limits. Overcomprtession by itself doesn't hurt a seal. It is the enormous forces it sees to get unseated that can break it. If you have the capability to chauck the exhaust valve and spin it fast and true you can reface the exhaust seal and cut the brass shoulkder back and get another lifespan out of the seal.
If they continue to get used with all the stiction associated with the enormous amount of contact area they will fracture the center right out of the valve and the hammer will just push the middle through the outside and the gun will fail.
Seals change their structure over time by getting softer or harder depending on their particular compound. We don't know up front which will happen but they won't stay the same over time. Nothing man made does.
We will learn what will fail when it fails and all I say is why stress stuff beyond what it can obviously tolerate.
Force over time tells us there is an accumulated effect based on the pressure level the customer chooses. More pressure simply means more force with time and temperature adding to the stresses.
Soft goods will always need to be changed out periodically but the availability of those parts and cost of manufacture might make you want to get the max life out of what is in there so it doesn't becomea hassle to get fixed later.
I know it takes about a decade for an overtight Dan rear sight to break the solder joint. If I remove everyone that goes thru my shop, stretch it so it isn't overtight and reinstall it those guns will NEVER SUFFER FROM solder joint failure.
When you know something preventable will happen and prevention means you store at 100 bar what do you have to lose?
If you store at 100 bar not knowing if it will help, maybe in 20 years you will learn you were one of the lucky ones that still has a gun to shoot. No downside!
We test guns to failure so we see what fails first, second etc.
If we fix the weak link now the weak link is the shooter cause now he is the pressure relief. A pressure relief with a brain is the best kind.
Be kind to your gear. Machines don't like to hammer themselves but they will faithfully if that is how they are used till they fail. I like stuff that isn't stressing itself to operate and so often when the seal engagement to the surfaces they seal to is too much the system isn't going to operate like it was designed to operate.

[Nomadic Pirate]

I'm definatly in the "store your PCPs at 100 BAR" camp,...just trying to figure out if storing a Talon Pistol .25 at 150 BAR is really that bad for it.