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View Full Version : Why You May Want to Use CO2 Instead of HPA


DFSniper
04-10-2008, 05:16 AM
this isn't mine, but i ran across it on another forum:
Link to Original Thread (http://forums.paintball.com/index.php?showtopic=28497#)

Why YOU should consider using CO2 instead of HPA

These days, every where you go you’ll hear the chant “Get HPA”, “Never use CO2 on a high end gun”, “If you can afford HPA there is no reason to use CO2”, etc. HPA does have certain advantages, but most of the ideas that a majority of people have concerning HPA and CO2 is based on one thing – BS

BS#1 – HPA is in everyway better than CO2

This is nonsense. Without even thinking, I can name one advantage of CO2 over HPA – Shot capacity.

http://img521.imageshack.us/img521/2015/graphco2vshpaps2.jpg

We know that CO2 maintains a constant vapor pressure of about 850 psi @ 70 degrees from 100% fill down to about 18%. Below 18% fill there is no longer ANY liquid CO2 in the tank. That is why the pressure drops linearly just like compressed air or any gas for that matter. In otherwords, from @ 18% capacity a CO2 tank behaves completely like a HPA tank of the same volume with 850 psi of air in it – the fact that the gas is CO2 and not N2 or Air (78% N2 20% O2 and 2% other stuff) has no bearing on its pressure/volume relationship as long as everything stays gaseous -- remember PV=nRT; the Ideal Gas Law? Therefore, there should be no difference whatsoever between two tanks of equal volume @ 850 psi, whether it is filled with HPA or CO2, in terms of the number of shots you can get out of it.

We also know that at 100% capacity, a CO2 tank has 5.5 times as much propellant gas as it does 18%. Therefore we can expect 5.5 times as much working gas from a fully filled Co2 tank as one @ 18% capacity. If the gas doesn’t liqueify, then you’ll have to pressurize it to 5.5 times the pressure to squeeze the same amount of working gas into the given volume. That is for a HPA vessel, you’ll get 5.5 times as much working gas compared to the same vessel @ 850 psi if it is filled to 4675 psi.

What we can deduce from the above is that a CO2 tank is roughly equivalent to a HPA tank of the same internal volume filled to 4675 psi. The difference is that for CO2, from 18% capacity onwards pressure is constant and part of the gas liquefies. For HPA, pressure just keeps going up. Because the CO2 vessel does not need to be rated for 4500~5000 psi, it can be made lighter and cheaper.

BS#2 – HPA is more consistent than CO2

OK, this is generally true. HPA setups are generally more consistent than CO2 setups. But this is not because it is HPA. It is because CO2 is sometimes used unregulated (as is frequently the case with Tippmann users) or with a single regulator, whereas HPA is almost ALWAYS double regulated. A single regulator will have an effective ratio of between 50:1 to 100:1. That is on the average, the output pressure increases 1 psi for every ~75 psi drop in input pressure*.

In a double regulated setup, the output pressure from the high pressure regulator on the tank (when you go from 4500 down to 900 psi) will increase by about 48 psi. This is why there has to be a second regulator inline between the first and your marker’s gas input. The second regulator reduces the output pressure fluctuation to only a 0.64 psi decrement. This is where HPA’s consistency comes from.

http://img138.imageshack.us/img138/228/graphco2hj6.jpg

In a CO2 tank, the pressure changes are actually MUCH LESS than in a HPA bottle. At 70 degrees F, CO2 is practically constant pressure between 15% fill and 100% fill – about 850 psi. The major change in input pressure from a CO2 tank comes from the chilling of the tank due to vaporization of CO2 within the tank which is an endothermic process -- which can be substantial sustained high rates of fire. If you empty a whole hopper in five or six rapid bursts, you stand to chill the tank by about 20 degrees F. This reduces the tank temperature to roughly 50 degrees F. At this temperature, the vapor pressure is roughly 660 psi. This is a 190 psi change, but still significantly less than what you will experience in a HPA tank. Even at a freezing 30 degree F CO2 maintains a constant vapor pressure of ~500 psi from 100% down to almost 10% of its tank capacity. Remember it takes a lot of shots to effect the kind of temperature change we are talking about, and even then CO2 has less pressure change than HPA. Also, at any particular temperature, CO2 holds constant pressure for almost 90% of the tank’s capacity, HPA on the other hand loses pressure constantly from 100% down to 0%. Hence, CO2 setups only need ONE regulator to maintain reasonable output consistency – about 4.7 psi across 40 degrees of temperature flux. This is MUCH less than the operational output flux of 48 psi were you to use one step regulation on a HPA setup!

Now, comes the best part – who says you cannot use double regulation with CO2? Put two regulators inline and you’ll get a level of consistency which can exceed that of HPA setups! I do it on my Ion, and there a quite a number of Automag users in the old days which run a pre-reg between their CO2 tank and the A.I.R in the Automag.

* This holds true until the input pressure drops below the set output pressure at which point the regulator becomes effectively a gas-through foregrip (or a gas-through cylinder), and the output pressure is the same as the input pressure.

BS#3 – CO2 cannot be used with high end guns

Yes, a lot of high end marker manufacturers tell you that using CO2 in their guns voids the warranty. And there is a good reason for that – IDIOT USERS. Whereas doing something really stupid can cause a HPA tank to blow up and maim you, that is not really the marker manufacturer’s problem. However, running liquid through a electro-pneumatic marker can trash your solenoids which is the manufacturer’s problem!

The fact is that as long as you use an anti-siphon tank (and orient it correctly), use a regulator and do not do moronic things like fire 30 shots with the marker upside down. You are not going to get liquid in your marker. Even if a little liquid gets into the anti-siphon tube it will boil off before getting to the reg for the most parts. If not, it’ll boil off within the reg or at the regulator output where pressure is 140~400 psi on most higher end guns. The chances of you getting an incompressible liquid slug into the solenoids is practically zero. Even if you shoot 5 or 6 shots sideways or upside down, it is not going to happen. You have to literally dump two or three dozen shots while drawing liquid to screw up.

Another concern is whether the marker – or rather its lubricants – will function as CO2 chills down. Well, if you marker uses Dow 33 grease or a proper marker oil like KC Oil, it will. It will because these lubricants will work way below 0 degree F and at that point you’ll run out of working pressure before you run the lubes solid!

BS#4 – CO2 is a dirty gas

We are not exactly running medical grade CO2 in our markers. So I wouldn’t venture to say the CO2 we use is squeaky clean. But all you have to do is look at a mesh filter placed between a tank output and an ASA adapter after a dozen paint balling sessions. Let me tell you want you’ll find… probably nothing. I rest my case.

BS#5 – CO2 is less safe than HPA

Actually I think the reverse is true even though neither is really dangerous unless you do really moronic stuff to it. CO2 cylinders will withstand about 1500 to 2500 psi before bursting the pressure relief disc. HPA tanks also have safety releases to prevent them from blowing up due to over filling. But fiber wrapped HPA tanks are actually much more delicate than any CO2 tank. From a safety stand point, a 850 psi pressure vessel is inherently less dangerous than a 3000, 4500 or 5000 psi one.

Conclusion

You SHOULD consider HPA and CO2 based on their respective merits.

Choose HPA if you do not need shot capacity but somehow feel the need to shoot 3 hoppers full at 20 bps in 2 minutes. Choose HPA if you enjoy free air at your local field or you like to do the DIY Scuba fill stuff. Choose HPA if you somehow feel the need to shoot the gun sideways or upside down all the time – I don’t know why you will want to do so and you’ll need to address your feed problems first by getting a Q-loader or the like.

For most other purposes, you should consider CO2. You’ll get a lot more shots for the same bottle size. You’ll hence be able to avoid having to trek back to the fill station between games. You can actually get as good or better consistency with CO2 if you invest in a second regulator – a convenient route is to use a Palmer Stabilizer Female in place of your current ASA adapter and retain your current reg. Even if you don't a good single regulator will give you immaterial consistency differences between CO2 and HPA. CO2 tanks are also a lot more affordable than HPA tanks, and generally a lot more hardy. Just remember… ALWAYS use an anti-siphon tank (unless you use a remote or vertical bottle) and never do stupid things like shoot two dozen rounds upside down for dry firing fun at the chrono.

Kenny_McCormic
04-10-2008, 05:18 PM
Another thing on safety, co2 is inert so you can put all the oil you want into a co2 tank and have nothing bad happen.

HelpDeskHustler
04-10-2008, 06:13 PM
It should be noted however that CO2 tanks do have a tendency to dislike hot cars and extreme hot weather a lot more than Hpa, and that although it's not recommended that any tank sit in a overly hot environment, a full co2 tank can blow it's burst disk in less than 120* areas. Hpa requires a much greater temperature since a majority of the air is hydrogen.

HelpDeskHustler
04-10-2008, 06:28 PM
I'd also like to see a comparison of the coefficient of volumetric expansion between co2 and hpa.

poker_jake85
04-18-2008, 02:13 PM
HPA Rocks, no freezing internals, no broken o-rings, less mantainence.

DFSniper
04-18-2008, 02:32 PM
HPA Rocks, no freezing internals, no broken o-rings, less mantainence.



The fact is that as long as you use an anti-siphon tank (and orient it correctly), use a regulator and do not do moronic things like fire 30 shots with the marker upside down. You are not going to get liquid in your marker. Even if a little liquid gets into the anti-siphon tube it will boil off before getting to the reg for the most parts. If not, it’ll boil off within the reg or at the regulator output where pressure is 140~400 psi on most higher end guns. The chances of you getting an incompressible liquid slug into the solenoids is practically zero. Even if you shoot 5 or 6 shots sideways or upside down, it is not going to happen. You have to literally dump two or three dozen shots while drawing liquid to screw up.

Another concern is whether the marker – or rather its lubricants – will function as CO2 chills down. Well, if you marker uses Dow 33 grease or a proper marker oil like KC Oil, it will. It will because these lubricants will work way below 0 degree F and at that point you’ll run out of working pressure before you run the lubes solid!

promblem solved.

poker_jake85
04-18-2008, 02:51 PM
Go to PBN and post this in the Ego and Dye forums...

DFSniper
04-18-2008, 03:24 PM
lets not go there... i bet half those guys have never even used co2, and i'm speaking from first-hand experience...

and i bet they'd be so against the idea that none of them would dare try it in fear of ruining their $1200+ guns

poker_jake85
04-18-2008, 04:20 PM
That would just be funny to see what they would say, I bet 1 of 10 might try it. Personally I wouldn't risk it either, if you have the money to buy a gun like that, another $150 more on an HPA tank is worth it.

nirvana21
06-11-2008, 06:02 PM
alright, so what do u buy? waht kind of regulator for the co2 tank?

malJohann
06-12-2008, 12:13 AM
alright, so what do u buy? waht kind of regulator for the co2 tank?

Bob Long or Palmers.

cyberthrasher_706
06-12-2008, 06:47 PM
the part about CO2 not being dirty, I have to call bull. I recently acquired a marker that had only been run on CO2 and started my cleaning of everything. That caked on white buildup in the front block, had to take my dremmel to it with a buffer wheel. The valve spring was so caked in it that it would hardly compress. It probably still comes down to moronic users on some of that, but it shows that CO2 is dirty, just not exactly in the same terms as the author.

Paradox313
06-18-2008, 06:30 PM
You still are never going to get me to shoot CO2 again.

slim and shady
06-22-2008, 07:46 PM
I personaly like HPA alot better then Co2 however i think the differences between them can be far exagerated(SP). I think HPA is the way to go however if someone chooses Co2 that is there preference and deserves no ridicule from me.

vikingshadow
06-23-2008, 07:56 AM
I agree with ^^^^. No one deserves ridicule for anything, let alone something that simple. I don't have a problem with using Co2 (in my pumps and in my Spyders) but if the manual says not to use it, I'm not using it! There's got to be a reason for it...

timbertiger20
08-11-2008, 01:08 AM
Haha............Ok let's set a couple of things straight here..........there are alot of false statements in the whole thing. Who is he kidding? I work at an HPA/CO2 fill station..........let's point out a few things......

First off safety............you right..........Co2 is not as high of a pressure as HPA. However which do you see blowing more burst discs? If your hand is near the burst disk you will be seriously injured. The pressure really isn't much of an issue! The 4500 PSI tanks have been tested to burst at almost 18000PSI. A regular HPA compressor tops out at 5K, some up to 6K. If you leave your Air tank in the car what happens? Not much. Not to say that burst disks can't be blown but it is rare and usually by the air operator not paying attention! So let's go to CO2 filling methods vs HPA filling methods. HPA is easy......open valve and fill to the magical button on the scale. CO2 tanks must be eptied and chilled to fill. Most fields I go to have an incompetent filler. I have had tanks filled to 50% over capacity by fillers. You must use a scale! You must make sure tank is empty! You must fill to no more than the rating on the bottle! Most tanks I take to get filled are either way under filled or way under filled. I am way more confident that the kid filling air even if he manages to screw up and puts 4500 in a 3000 psi tank is safer than a significantly over filled CO2 tank. If you notice alot of accidents recently have been from C02 tank valves coming unscrewed. HPA tanks rarely come unscrewed and have safety measures to prevent this from happening! Most CO2 tanks do not. Neither is totally safe.........want safe......play ping pong! Oh one other thing............I was using CO2 awhile back in a landmine..........the landmine exploded with my Palmer's reg. Turns out it malfunctioned and instead of regulating to 70 psi........my reg froze and let all of the liquid CO2 into the system........nearly killed me! The box it was encased in exploded, every pipe exploded, several parts hit me in the chest and I broke a standard male air fitting when it hit me in the chest. I won't ever use the CO2 in a single regulated system again!

Efficiency..........well here is some suprising news........his chart is correct his logic is not! I play lots of pump ball. Ever try it with CO2 in cold weather? It's useless! Do you know what happens every winter here? Everyone buys HPA tanks. Take that same chart and apply it to 30 degrees. CO2 only puts about about 400 psi. I get almost 4 shots out of a phantom on a 12 gram! Oh guess what..............get the +/- 3 balls worth out of the 13 cu. in. HPA tank on my phantom. Efficiency........sure in the summer at 100 degrees that heavier 20 oz tank will do about the same as a 92/4500 tank. Your just adding 1lb 4oz. to your setup to compete with air at less than 1oz. Just remember when markers come out every one quibble's about 1 oz of weight removed for an extra $100.

Cleanliness............I also repair a few markers.........typically I have to remove those filters out of Spyders due to blockage! It's not our HPA as the air is tested several times per month for water, and purity.......it's scuba air!

To answer Vike's question on why you follow the instructions.........it's been proven that markers do not operate the same when using CO2! Here's why.........CO2 is much more dense than air.......it does not rise when it's released from the bottle because it is heavier. The weight of the gas can actually cause some markers to malfunction or operate inefficiently. Remember that marker parts are getting lighter and lighter weight. Using a heavier gas can actually cause those pieces to move differently. Remember you usually have some kind of an air balancing act in EP markers. It also doesn't help that the CO2 in your marker is constantly changing. Think about it. As soon as CO2 enters your marker it's regulated. But what happens to the gas beyond the regulator? It goes into storage areas and the marker body. You take a small amount of gas and it expands! If you have a small amount of CO2 on the LPR side and a large amount of CO2 on the opposite side..........depending on the chambers and the amount of surface area of the aluminum this gas could cause uneven expansion inside the marker. Hence one of many reasons you wouldn't use CO2 in that type of marker. Sure it's great in Spyder's and Tippys........they aren't using double regulators and sophisticated balancing acts..........although some of you do know they can be a pain to balance! How about those spring changes every game? How many times do those of you using HPA do that.........well if your tank has a decent regulator............NEVER! What about Water? The CO2 can and will cause moisture to build up around your solenoid. Just like on the outside of your bottle during high gas release. It can cause condensation on your solenoid during high rates of fire. Another reason you listen to your marker manufacturer. Those solenoids have very specific applications. Most are not designed to get wet!

Now onto someone else's comment...........CO2 is not an inert gas! Take a look at your Periodic Table of Elements.........now find CO2.........it's not an element! CO2 is very simply one carbon molecule combined with two oxygen molecules. Oxygen is a gas on the element table.........so is Carbon. The very definition of an inert gas is very simple it's a gas that does not easily mix with other elements. Obviously Oxygen is also not inert as it mixes with Carbon and Hydrogen very easily hence H20.

Not ridiculing Vike..............I'm teaching :D

Quick add on..........yes anti siphoning helps alot...............if you always make sure the tank siphon is straight up. Also let me point out for you remote user's..........if the tank is straight up...........don't anti-siphon! Also remember your tanks is alway pointed the same direction...........unless it's not. Anti siphoning and positioning works great..........but not all of the time...........shooting up and down can cause problems.........laying on the ground can cause alot more!

mced
01-02-2009, 10:57 AM
Go try this with any high end gun, that you have purchased. Not someone elses, do it to yours so you will care when u fk it up.

oldironmudder
01-02-2009, 11:50 AM
I ran Co2 through my EM1, which has a noid similar to "high end" markers. Did it freeze it? No, I blew the gasket but that was my fault for messing with the LPR. All I had on the marker was a crappy Bob Long Torp & anti-siphon tank.

Personally, I would gladly run Co2 through a "high end" marker just to see what happens.

Modded-Like-Hell
01-02-2009, 03:08 PM
well... i ran C02 a long time ago on one of my LP spyder (when i wasnt rich enough to run HPA), tank wasnt even anti-siphoned...a regular 12oz java tank and the reg(AIM SHOCK REG) would freeze up and mess the rings up... what i know is that c02 messes up orings.

if the manual (i hope we all read it before we go out and play) says "HPA or compressed air only" theres a reason for that........WARRENTY COVERAGE!!!

come on!!! someone else said "if u got money to go out an buy a $1200 marker...then u diffenetly have $150 for HPA tank!!!"

click here (http://www.actionvillage.com/031-187-0001)

even the less fortunate players can buy one for cheap!!!

DFSniper
01-03-2009, 01:41 PM
hmm... i just thought about this. i have a NXT shocker manual in front of me, and it says it CAN run off of antisiphoned CO2.

Modded-Like-Hell
01-03-2009, 03:35 PM
i think most of the smart parts markers u can run anti-sphioned co2...the sft says u can and the ion too... im suprised that shockers u can use them since they have like a billion o-rings in them

oldironmudder
01-03-2009, 03:38 PM
The old shoebox shockers could handle Co2. I dont see why you cant if you take the right steps to prep the marker & dont be stupid & pull 30bps full auto with an overfilled tank.

DFSniper
01-03-2009, 03:44 PM
my friend asked me something today: why cant the slg run on co2? the only conclusion we've come to is because of the hyper reg.

Modded-Like-Hell
01-03-2009, 03:48 PM
same goes for the PMR

ProFalcon
01-06-2009, 01:08 PM
well said timber tiger!

as timber said, the problem with CO2 getting at the noid isnt that the liquid CO2 goes all the way from the tank through the asa and macroline, through the reg, through the LPR, and into the solenoid. there is no way that CO2, a liquid that expands into a gas would travel that whole distance in liquid form, as the original CO2 enthusiast mentioned. that is damn near impossible. it is the density of the gas condensing inside the small chambers of the solenoid that causes the problems. i dont know about you guys, but i dont want anything condensing near tiny orings and seals.

and on the weight issue:
sure an empty CO2 tank might weigh less than an empty HPA tank, but fill the tanks and then tell me which is lighter. my days of lugging a 20oz are over.

HPA tanks are made to way way way higher standards than a CO2 tank aswell. not even a close comparison for the safety issue. sure it has more pressure, big whoop.

Solar
01-13-2009, 08:57 AM
One problem I've found with HPA is that I had some recocking issues with my LP spyder. I was running at 300 PSI 285 FPS on anti syphened CO2 with a palmers stabalizer an Maddman Rocket Valve when the front block was getting too cold so i switch to HPA tank (it's free to rent with admission at the place I play). After I switched to HPA I could not recock with out the back pressure of my Halo.

So as soon as the halo was empty it would jack hammer and decock.

I did not have the problem with CO2.

A&H
01-16-2009, 01:25 PM
One problem I've found with HPA is that I had some recocking issues with my LP spyder. I was running at 300 PSI 285 FPS on anti syphened CO2 with a palmers stabalizer an Maddman Rocket Valve when the front block was getting too cold so i switch to HPA tank (it's free to rent with admission at the place I play). After I switched to HPA I could not recock with out the back pressure of my Halo.

So as soon as the halo was empty it would jack hammer and decock.

I did not have the problem with CO2.

some LP spyders need the back pressure of a ball to recock, personally i think that alittle more tuning is needed to solve that little issue, however some people set there operating pressure that low on purpose. (i personally want a marker that cycles loaded or unloaded)
and HPA will give you more consistant performance, aswell as being alittle easier on the marker. (orings last longer)
your tune will also differ greatly from co2 to HPA, some minor tweaking and your recocking isue could have been solved and i think you would have been much happier with HPA. :)

oldironmudder
01-16-2009, 04:15 PM
When I tune my blowbacks, I set the reg & springs to where it will recock on its own with no paint or a barrel.

andover85
01-16-2009, 04:34 PM
Ok, granted you could theoretically run a high end gun off of co2. But for the safety of the masses of people not smart enough to take the precautionary measures to prevent damage. I would NOT recommend the usage of co2 in high end guns. Another thing, for casual players that don't need a constant 13-15 bps for 5-10 min game co2 will most likely work. But for those tourney players out there that need to play at those bps levels co2 will absolutely not work!!! Another thing it doesn't take 20 bps to get co2 cold, try 10 bps for 15 secs, the tank will be cold and I guarantee there will be condensation where you do not want it. Again co2 has the possibilities to run through high end markers with the absolute utmost care taken but think: is the money spent to get a reg for the co2 tank and the constant worry about ruining your $1000 investment worth it? for me its not, that's why I run HPA.

Note: co2 is a heavier gas than HPA and therefore allows for a lower pressure in lp Spyder applications.

Another note what kind of line supplies the gas to your marker in all high end applications? Macroline, this line is not rated for co2s inconsistency when unregulated and will blow, I have had this happen, it nearly put a nice piece of metal in my foot. Also for the regulated co2 it isn't uncommon for the reg to freeze and allow a lot more pressure where it is not needed(blowing the macroline or ruining the reg/internals on your $1000 investment).