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Old 07-17-2009, 10:08 PM   #51 (permalink)
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Quote:
Originally Posted by HP_Lovecraft View Post
.

But there will be no liquid co2 in the tank. It will have all converted to supercritical co2, and be impossible to measure.
Shane-O:

That is how I understand it - and how Bill Mills, make of said chart, explained it to me as well - as he is in Florida.

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Old 07-17-2009, 10:48 PM   #52 (permalink)
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Quote:
Originally Posted by HP_Lovecraft View Post
That is not true at all.

Here is the graph they tried to show:
http://montneel.selfip.com/paintball/co2.gif

That "bell curve" shows the supercritical boundry for co2. Basically, it is 88 degrees ambient. But black co2 tanks in sunlight can hit 88 degrees when the ambient is just 80 degrees.

Regardless, at 88 degrees, the pressure is still about a 1000psi, FAR from blowing a 1800psi burst disc, and nowhere near a modern 3000psi.

But there will be no liquid co2 in the tank. It will have all converted to supercritical co2, and be impossible to measure.

I think what I am missing is the "Super critical" part of it. Are you saying that super critical Co2 still boils off to provide the pressure, but it is in a gaseous state at that time? Or how can Co2 be in a gaseous state and not exceed 1000psi or so?
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Old 07-17-2009, 11:19 PM   #53 (permalink)
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Originally Posted by Shane-O View Post
Are you saying that super critical Co2 still boils off to provide the pressure, but it is in a gaseous state at that time?
I think this is correct. Not sure if boiling is the right word anymore, but thats how I understand it.

CO2 is funny stuff.
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Old 07-17-2009, 11:29 PM   #54 (permalink)
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Quote:
Originally Posted by Shane-O View Post
I think what I am missing is the "Super critical" part of it. Are you saying that super critical Co2 still boils off to provide the pressure, but it is in a gaseous state at that time? Or how can Co2 be in a gaseous state and not exceed 1000psi or so?
The "supercritical" point of CO2 is around 88 degrees F.

Technically, above this temp, the density of the "gas" state increases, and the density of the "liquid" state decreases, such that there's no distinct phase -- it's just a "supercritical fluid" at that point. You won't get a distinct "liquid" even if you increase the pressure past critical temp.

I know you guys are Hell bent on this point, but that's OK, because I have a solution to this conundrum. Here's how you chill your tank below 88 degrees, easily, while it's still 90+. Even in Texas. Are you ready?

Crack off a few shots. If you're in-game, you're probably already doing this anyways. You see, releasing CO2 from your tank has the side effect of cooling it off...

That's why people whine about installing anti-siphon tubes, EVEN IN TEXAS, where the temperatures should put the tank above "critical" all the time, and thus there shouldn't ever be any liquid in the tank to get into your marker. Right? Anti-siphon guys, feel free to argue with the "it can't possibly be liquid in Texas" guys. Hopefully you will cancel each other out.


Anyways, I think some of the new features are great. The integrated nature of the valve design is a good idea. The fill meter is also a good idea.

The overall tank redesign is questionable. Hydro testing is a question mark. I'm not so sure I like the way they did the burst discs on some of the smaller tanks (I've seen these in person.) And lastly, I also belong to the camp that likes to run around with 2" diameter tanks.

Who cares if it came from JT or somebody else who you deem not worthy to produce paintball products?


Those of you who talk about bringing your own scales to your field: how many of you actually DO it?
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Old 07-18-2009, 12:35 AM   #55 (permalink)
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Quote:
Originally Posted by GoatBoy View Post
The "supercritical" point of CO2 is around 88 degrees F.

Technically, above this temp, the density of the "gas" state increases, and the density of the "liquid" state decreases, such that there's no distinct phase -- it's just a "supercritical fluid" at that point. You won't get a distinct "liquid" even if you increase the pressure past critical temp.

I know you guys are Hell bent on this point, but that's OK, because I have a solution to this conundrum. Here's how you chill your tank below 88 degrees, easily, while it's still 90+. Even in Texas. Are you ready?

Crack off a few shots. If you're in-game, you're probably already doing this anyways. You see, releasing CO2 from your tank has the side effect of cooling it off...

That's why people whine about installing anti-siphon tubes, EVEN IN TEXAS, where the temperatures should put the tank above "critical" all the time, and thus there shouldn't ever be any liquid in the tank to get into your marker. Right? Anti-siphon guys, feel free to argue with the "it can't possibly be liquid in Texas" guys. Hopefully you will cancel each other out.


Anyways, I think some of the new features are great. The integrated nature of the valve design is a good idea. The fill meter is also a good idea.

The overall tank redesign is questionable. Hydro testing is a question mark. I'm not so sure I like the way they did the burst discs on some of the smaller tanks (I've seen these in person.) And lastly, I also belong to the camp that likes to run around with 2" diameter tanks.

Who cares if it came from JT or somebody else who you deem not worthy to produce paintball products?


Those of you who talk about bringing your own scales to your field: how many of you actually DO it?
Good points. I understand a bit better now. When its super critical its basically in between states. Got it now. All other points are right on the money, thanks for the help.
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Old 07-18-2009, 11:16 AM   #56 (permalink)
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I think that the hydrotesting issue with these cylinders is a moot point. Who really gets 20oz hydrotested anymore anyways? I believe the test would cost the about the same, or more, as a new cylinder.

Dan
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Old 07-18-2009, 09:28 PM   #57 (permalink)
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Originally Posted by dempsey626 View Post
I think that the hydrotesting issue with these cylinders is a moot point. Who really gets 20oz hydrotested anymore anyways? I believe the test would cost the about the same, or more, as a new cylinder.
I think this is what will doom these tanks. All things being considered, they cost more for something people are not really wanting to pay for.

Who remembers the Tippmann Quick-Fill CO2 tanks? That was a really smart invention that allowed people with co2 tanks to fill them like HPA tanks. Basically, while still on the gun you just plug them in, whoosh, and tank is filled. no chilling or measuring.

Great idea, but they cost more, and required special fill-stations to work with them.

As for me, I have a few annodized tanks. SO I have no choice to keep hydrotesting them. Some have been tested 3 times already.

Quote:
Crack off a few shots. If you're in-game, you're probably already doing this anyways. You see, releasing CO2 from your tank has the side effect of cooling it off.
On a really hot day, that method will not come close to chilling the tank enough to drop below supercritical. For those of us that run siphons, that makes a difference between playing and not playing. Back in my tournament days, I did not fool around. I'd hold the cocking knob forward while screwing in the tank so the co2 rush out for a few seconds
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Old 07-19-2009, 12:03 PM   #58 (permalink)
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Quote:
Originally Posted by GoatBoy View Post

Those of you who talk about bringing your own scales to your field: how many of you actually DO it?
It is a moot point, as on my Phantom I get x amount of shots off my 4ounce tank. I do the weighing of my tanks when I fill them prior to going to play.


CO2 only exists as a liquid above 5.1 atmospheres of pressure, so chances are a "full tank" will not experience complete boil off until enough volume has been removed from the tank to allow it. Otherwise if a "full" tank instantly boiled off the increased volume would pop the burst disc. CO2 is some neat stuff in the way it reacts to tempature and pressure.
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Old 07-20-2009, 10:02 AM   #59 (permalink)
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Quote:
Originally Posted by HP_Lovecraft View Post
Who remembers the Tippmann Quick-Fill CO2 tanks?
Me! Me!

These are the standard for rentals at Hell Survivors, they've used them for years without much trouble that I know of, works really well, you don't know how much is in you're tank, but you can top off every few games.

Shame it died out, HSI is keeping on with the valves they've got for now.
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Old 07-20-2009, 12:07 PM   #60 (permalink)
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Goat,

I really think you could not have put more words in my mouth. I shoot a pump. When I play on C02 (rarely) I do so in stock class mode. I will wager the BPS I hit will not reduce the tank temperature long enough to create a significant drop in pressure for a significant amount of time to create much, if any, liquid in my black tank.

I wasn't 'hell bent' and was not arguing against anti syphon guys.... I run a veritcal 3.5 ounce tank or an anti syphoned 9 ounce. I was simply trying to explain that this particular guage would not work well in Texas - while admitting that it would work well in the majority of JT's customer states.

I don't think I could be more ambivalent about my statements. I really have more **** to be incensed about. World hunger tends to piss me off, for instance - especially when I see fat chicks.


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