I just recently got a crossfire 68ci/4500.

I filled it up 2 week ago to 3k and took to home and didnt use it till the weekend. When I went to use it, it still sayed 3k.

I used all the air and had it filled up to around 4100. I took the tank home and the next day look at it and now its at 3800.

Do I have a leak?

Or is this normal?

When you fill compressed air tanks the compression of the air molicules create heat. you should feel the warmth of the tank after filling, anyway when the tank cools too room temp. the air inside also cools which in turn lowers the PSI in other words this is a natural occurance.  When I fill breathing air tanks for the local fire dept. I place them in a cooling tank to fill, this prevents psi loss and shrinkage.  Don't let it bother you unless it drops more than 600 lbs then you might have a leak

CHUNGENILE wrote: I just recently got a crossfire 68ci/4500. I filled it up 2 week ago to 3k and took to home and didnt use it till the weekend. When I went to use it, it still sayed 3k. I used all the air and had it filled up to around 4100. I took the tank home and the next day look at it and now its at 3800. Do I have a leak? Or is this normal?

When you fill an HPA tank the gas coming out of the filling station hose expands as it goes through the nipple. As the pressure builds in the tank the air is compressed to higher and higher pressure. This compression causes the air to heat. You have probably noticed that the tank gets warm as you fill it.

When you finish filling the tank is warm and says 4500 psi on the gauge. As the tank sits and cools the pressure drops, possibly as much as 500 psi, so the gauge now reads 4000 psi.   

You know, those gas laws you learn in chemistry class? (P1V1/T1=P2V2/T2)

You should be aware that you can fill a tank so quickly that it will over heat causing a de-lamination between the fiber-wrap and the inner aluminum tank. The damage may go undetected until the next hydro-test at which point the tank is a throw away.

Bruce A. Frank wrote: You should be aware that you can fill a tank so quickly that it will over heat causing a de-lamination between the fiber-wrap and the inner aluminum tank. The damage may go undetected until the next hydro-test at which point the tank is a throw away.

The bad thing is, is that that's how most of the shops fill.  Especially the younger kids.  I'm suprised they don't teach the shop guys that.  I will be filling my tank myself, now that my teammate got his old scuba's recertified (re-hydro'ed).  By the way, the local scuba shop fills my paintball tanks and puts it in a bath while filling, to keep it cool and to get the right pressure....

Thanks alot guys. I was starting to get mad and was going to tell the guy off that sold it to me.

I guess I just got a lesson in HPA 101.

spudcrazy wrote: Bruce A. Frank wrote: You should be aware that you can fill a tank so quickly that it will over heat causing a de-lamination between the fiber-wrap and the inner aluminum tank. The damage may go undetected until the next hydro-test at which point the tank is a throw away. The bad thing is, is that that's how most of the shops fill.  Especially the younger kids.  I'm suprised they don't teach the shop guys that.  I will be filling my tank myself, now that my teammate got his old scuba's recertified (re-hydro'ed).  By the way, the local scuba shop fills my paintball tanks and puts it in a bath while filling, to keep it cool and to get the right pressure....

At our regular field we fill our own tanks from the field filling station. I am constantly suggesting to other players that they should crack the valve only half way so that pressure builds more slowly in their tank. I get a lot of those, "What, are you stupid? I'm in a hurry to get back on the field" looks.

An interesting side note. If you freshly fill, then while the tank is still hot go ahead and chrono, you may find that when you get out on the field (tank's cooled down now) your velocity may be 30 to 50 fps slower than what you just chrono'ed. Warmer air traveling through even the best regulators tends to give different pressures once things cool down.

If I have to fill just before chrono, I barely crack the valve and only fill to about 1/3 of my full pressure. The tank stays cool. I then top off after chrono. The walk to the field then gives the tank time to cool. Also topping off after a partial fill, even if filled a little fast, will be cooler than a tank filled all the way from empty...unless you really take your time.

Well its been 4 days now and I still havent gotten a chance to play. I go back and check my tank and its at 3300 now!? It droped another 500 in 4 days. Its looking like if I leave it sitting with no use for a few months all my air would be gone.

Is this still normal?

Is it bad to keep alot of air in your tank for long periods of time?

Well its been 4 days now and I still havent gotten a chance to play. I go back and check my tank and its at 3300 now!? It droped another 500 in 4 days. Its looking like if I leave it sitting with no use for a few months all my air would be gone.

Is this still normal?

Is it bad to keep alot of air in your tank for long periods of time?/QUOTE]

Actually, it is normal, or should I say, rather, that it is not uncommon. There are valving seats in the neck that are susceptible to trash just like the power valve in the marker is. There is significant opportunity for dirt to enter the tank and get into the valve and regulator every time you refill the tank...particularly on field.

If you haven't kept the nipple cover in place while playing or the filling station coupler that you connect to your tank was last used by a guy who'd fallen in the mud before his last refill...leaving internal contamination on that coupler...which enters your tank at refill.

The valve and regulator of the bottle can be cleaned the same way you clean a leaky power valve. Squirt a few drops of oil into the nipple before you fill the tank up. 

Rather than putting the tank on the marker and firing it, which may carry the trash into the marker, I hold my tank neck down and bump the pin valve with the rounded end of a wooden broom stick  or the plastic handle of a screw driver.(don't bump the pin valve with anything metal as you may damage it) I bump it 5 to 10 times getting a strong release of air through the valve.

Wear your goggles when doing this. Trash ejected from the valve is flying at high velocity. If not wearing gloves the trash (grains of sand?) will hurt your hand when it hits. Even with my glasses on I have had ejected trash bounce around and hit me in the eye...wear the goggles!

You can check for leaks out of the pin valve, the fill nipple(and where it screws into the valve), or where the valve screws into the neck of the bottle, with a little soapy water. But really slow leaks may not show up.

If the oil treatment does not fix the leak, time to take it to the Airsmith.

I had a tank that leaked down over the week between games. Not enough to cause a problem in anyother way, but annoying.(I eventually cleaned it with the oil method solving the problem) I bought one of the screw on caps that protects the bottle valve. The cap seals against the tank neck "O" ring prevent any leakdown...even over months.

Why would "trash" inside the tank cause it to leak?

I have to wait till the next time I get air to do the oil method right?

Any paintball oil will work fine?

CHUNGENILE wrote: Can I get Hoppe's #9 oil  at any hardware store?

No, not at a hardware store.  But any Sports store that sells hunting equipment.  I know for a fact Wal-Mart sells it, because that's where I got mine.  It will be in the Sporting Goods area, where they the gun cleaning supplies....