Come! Show Me Why I Am Wrong

[AGD]

There is a HUGE amount of heat generated by the speed at which the valve recharges. The internal air of the chamber gets up to 180 degrees, friction on the parts is nothing. You guys can't just guess about whats happening in a marker.

AGD

[bleachit]

There is a HUGE amount of heat generated by the speed at which the valve recharges. The internal air of the chamber gets up to 180 degrees, friction on the parts is nothing. You guys can't just guess about whats happening in a marker.

AGD

is this the reason why a RT/X valve cannot be run on CO2?

[Z-man]

There is a HUGE amount of heat generated by the speed at which the valve recharges. The internal air of the chamber gets up to 180 degrees, friction on the parts is nothing. You guys can't just guess about whats happening in a marker.

AGD

I am not sure, but according to my calculations that was the slap being laid down.

[Plazmic]

See, now that's the kind of information I'm reading this for. And yes, I believe that was the slap being laid down.

[aut911]

No, basically the reason for why you cant run the RT/X valve on CO2 is due to the fact that the valve recharges SO fast, not to mention the fact that a long string would freeze a classic mag on a 70 degree day with an expansion chamber. Im guessing that the RT would be more susseptible to freezing than a classic because of the faster recharge rate. Its funny how one proppellent gas will freeze a valve with condensation, and another gas(HPA) will heat the valve to uncomfertable levels.

aut

[athomas]

The heat is generated by the compression of gas in the front chamber as the valve "recharges". In AIR valves it was not noticable due to the lower recharge rates. The retro valves generate heat because the gas is recompressed so quickly.

The freezing occurs at the back part of the valve where the gas decompresses from its input pressure. This decompression cause a drop in temp. The drop in temp causes the dew point of the CO2 to become lower. Therefore, some of the CO2 becomes condensation in the passages. The condensation can cause the o-rings to freeze and stop sealing. The gas absorbs heat energy from the valve and o-rings to become a gas again. This lowers the temperature of the valve passages. The more heat that is drawn from the valve, the cooler it gets. So, the faster you fire, the more heat is drawn from the valve. The heat from the recharge(even in a retro valve) is not a factor because it is discharged behind the ball. In a one shot scenario, the heat will help thaw the freeze and effectively cancel it out if the o-rings don't freeze first causing uncontrollable venting, which would result in a "runaway freeze" condition. This would only happen in the retro valve. The AIR valve handles the lower rates of fire and lower recharge rate quite effectively. Air has a different point at which it turns to liquid. Therefore, under normal and extreme operating conditions, the compressed air will never condensate. The low rate of heating and cooling are effectively cancelled out due to the lower recharge rate of an AIR valve. In a retro valve the front chamber heats while the drop in temp is dispersed over the volume of the tank. The valve heats because it sees more heat than cooling.

There is so much more that could be said here but hopefully this gets a basic explaination across.

[Z-man]

Well you did leave out why the CO2 freezes the o-rings even though both CO2 and the HPA discharge at the same rate. The whole phase change aspect of the CO2 is the largest cause of the freezing o-rings. Whenever you have a substance change phases (solid -->liquid, liquid-->gas, solid-->gas) it requires MUCH more energy per molecule than to raise the temperature of those molecules in the same phase.

Water is a good example. From 0C - 100C at 1 atm, 1 gram of water takes 1 calorie of energy to raise it's temperature 1C. It does not matter if its from 5C to 6C or 88C to 89C, under those conditions, that is the energy required. Now, at 1 atm water undergoes its phase change to steam. While it takes a mere 1 calorie to get liquid water from 99C to 100C, it takes 100 calories to change that same 1 gram of 100C liquid to 100C gas. Now CO2 does not have the same energy requirements (they are a bit less) but the same idea applies

That is the underlying reason for CO2 freezing down the Automag AIR valve and the reason for ANY marker that uses CO2. Unlike compressed air tanks that store N2 is the same phase, CO2 tanks (like a 20 oz for example) have 20 oz of liquid CO2 that has to have a crap load of energy put into it to change it into a gas state. Where does that energy come from? Largely that surrounding air and the person's hands. This is one reason why a coiled remote is helpful when using CO2. It adds a large surface area that can absorb the surrounding air much better and sunlight (as they are black).

The other thing you might need to consider is the "faster vs. slower" recharge rates. Mechanically, the valve design does not "speed up or slow down the incoming air (please explain to me if I am off on this). The reason for the slower recharge is because of the 2 very different gas systems.

At best when CO2 is room temperature (~21C) the vapor pressure of the CO2 is about 830psi. There is no regulator on a CO2 tank, whatever pressure is in there, that is what you got. That is BEFORE you start shooting the marker and dropping the pressure of the tank and thus causing some of the liquid to undergo it's phase change. Since it's near impossible at the CO2 systems are setup currently to keep the temperature constant in the air system so what happens is the the temperature (and therefore the pressure) of the CO2 tank drops as you fire the marker This problem is exacerbated when you shoot very fast, over long periods of time. This is the explanation of shoot down on CO2 tanks.

To add to the problem, unless you let give the CO2 sufficient time to warm up (somewhere between the tank and the valve) you don't get very consistent input pressures and thus shots on the marker. Also if you don't restrict the liquid from entering the marker, the phase change will occur in the AIR valve and THERE is where the problems arise.

First the evaporating CO2 freezes down the valve (no big deal for the steel but NG for the urethane o-rings.)

And second, the now evaporated CO2 hs a MUCH larger pressure than what originally came in the valve. This will give you a nice zinger if you gave it time to warm up. Say you are shooting nice and fast with your AIR Mag on CO2 and things start to freeze down and you see lots of that white stuff coming out . Then you decide to crawl around for a few minutes nd get into position. All that time the Co2 has been warming up and expanding. When you take that next shot you could pull over 350 just from letting it warm up. This is why HPA is superior; NO phase change, NO huge energy requirements and relatively consistent performance.