Are there any cons to an expansion chamber? Does it keep rof the same, or is it better? Is an anti-siphon tank the same as an expansion chamber? Why would any other gas system be better? I’d love some cites.
98 custom here in case you were wondering. Yeah, I know.
I wouldn’t say there are any significant cons to an expansion chamber. The idea is that it is an intermediate area that allows the CO2 to expand. Think of it as a gas reservoir. If any liquid CO2 gets sucked in, it will vaporize here instead of wreaking havoc with your gun’s internals. I don’t think it has any effect whatsoever on ROF, but it will give you a more constant delivery pressure, which should give you more consistent velocity, especially during rapid fire.
The big problem with CO2 is the fact that it is a liquid in your tank, with a vapor head. As you shoot, the pressure decreases as you draw off the gas. The faster you shoot the more the pressure drops. The liquid CO2 “boils” to replace the lost gas, but this does not always keep up with your ROF. Hence an expansion chamber gives you a bit of a buffer of gas. An anti-syphon tank really won’t provide a great deal of help; it’s just a bent copper tube inside your tank that prevents liquid from being sucked straight through the valve.
There are nitrogen systems out that solve the problem of pressure drop. N2 is all gas-phase, so you don’t have the issue of liquid CO2 needing to boil off to provide the gas needed to operate the gun. N2 systems are pricey though.
Hope this helps!
First off, don’t be ashamed of your Tippmann, it’s one of the most solid and reliable markers availible today. For recball, I wouldn’t use anything less.
No, it won’t affect your ROF whatsoever.
I’d say an anti-syphon is more effective than an expansion chamber (cheaper too) so if it’s a one or the other, go for the anti-syphon. (It needs to be installed specifically for YOUR marker, not the same make/model. Yours.) And don’t forget, with the recent death due to an improperly installed valve, get it done by someone who knows what they’re doing.
You also have several options if you want consistancy.
A) instead of an expansion chamber, get an anti-syphon and a regulator (I’d recommend one off of an Autococker, you can usually get them used for less than $20 USD) The cost should be less than a day’s worth of 'balling, and should help out your consistancy (and therefore accuracy) greatly.
B) An HPA/N2 setup, like Krisolov suggested. This, combined with a regulator will give the best results for your Tippmann. Make sure you have somewhere to get the tank filled, not all fields have HPA/N2 fills.
C) Tippmann 98s can run liquid CO2, instead of air. Doc Nickel (the same Doc that posts here, on the SDMB. Perhaps he’ll even grace this thread with his presence…) has a great article on this.
I’d recommend taking a good look around Doc’s site, he’s got some great information on there (and some beautiful customizations too.) It’s the closest you’ll come to an official cite on anything regarding paintball.
Is the expansion chamber going to give me more consistent pressure as opposed to an anti-syphon? I keep getting mixed responses to that. Doc’s site is quite thorough, is he reccomending going liquid only in cold weather, or is it better in general?
Very helpfull responses BTW. Thanks.
They’ll probably give the same consistency. It depends on the setup, bottle angle, etc. Heck, if you ditch the bottomline completely and just run the bottle vertically, the bottle will work as an expansion chamber, and the orientation will prevent any liquid from entering the marker, just as an anti-syphon would.
Expansion chambers aren’t as common now as they used to be. Most people have found that a good regulator like a Palmer Stabilizer works even better than an expansions chamber to block liquid CO2. The WGP reg I recommended earlier will do it 95% as well, but the Stabilizer is considered the best for that application… It’ll just cost you a whole lot more, although regs can be transferred to other markers, if you ever want to upgrade.
Running liquid only works in cold-mild temperatures. I used to try running a marker on liquid on a 35+ degree day (Celcius). It didn’t work out too well, to say the least. Some people swear by liquid CO2, and get good results, others don’t. So I can’t make a general statement. The M98 is known for running liquid well (Tippmanns used to only run on liquid, back in the old days, when semis were new) But again, only in cooler weather.
Can model 98s even run vertical bottle? And if they can, wouldn’t that make them VERY front-heavy?
I’d recommend getting both the anti-siphon and an expansion chamber. It’ll work really well and be cheaper than a regulator, and since Tippmanns don’t require ultra-consistent input pressure, you don’t really need a reg. Also, regs CAN freeze up from too much liquid CO2 (anyone used an Automag with CO2?). If you do want to get a reg, make sure you get one with a “high pressure” spring pack in it. Some regs that are designed for lower pressure guns, such as a 'cocker, will have a max output of 400-500 psi, which isn’t nearly enough to cycle your Tippmann.
I wouldn’t get a compressed air tank unless you do a LOT of cold weather playing. They are expensive, especially if you look at it as a percentage of the gun’s cost.
And, on a mostly unrelated note, any of you Doper PBallers in southern California? Interested in a Doper Paintfest?
My reputation preceeds me. 
Okay, first off, my CO2 articles are pushing five or six years out of date. I’ve been meaning to update them, but time is a valuable thing these days.
That said, a properly-installed anti-siphon is better than an expansion chamber. Simply put, the gas provides energy because it’s been compressed. If you allow it to expand before it does any real work (as in pushing a ball downrange) you’re simply wasting that energy.
An expansion chamber does help a bit as a “second stage” for the gas to absorb a bit more ambient heat, but as far as the average user is concerned, go with the anti-siphon. For an M-98, I usually recommend getting two good-sized tanks (12 to 20 oz) having them both fitted for anti-siphon tubes (fitted to the gun) and swap them out between games, so the just-used one can warm back up.
That’s not totally necessary though- if it’s warm there (60+ F on average) and you shoot less than a couple hundred balls per game, just get a 20-oz and run it with an anti-siphon. It’ll rarely cool off to the point of needing to warm up between games.
Yes, M-98s can run a vertical bottle, Tippmann has a vertical adapter that fits in place of the foregrip. Yes, it’ll be very front-heavy. Stick with the usual bottomline and short braided hose.
Don’t bother with running liquid CO2. Back when I wrote the articles, it was possible for most guns out there at the time (mechanical semi-autos anyway) but today, with the over-hyped push for “low pressure” operation (Tippmann’s guilty too) they’ve been increasing the valve chamber sizes and valve flow areas. Liquid is very dense, you actually want correspondingly small valves, you don’t need to flow a lot (as you do with lower-pressure gas-only.)
Because of this, the guns are far less tolerant of full-time-liquid use, and tend to be very inefficient. In any case, running liquid was really just a way to get early semiautos to keep working in the winter- few tolerated it in the high summer, and with the modern screw-in high pressure air systems, it’s pretty much fallen by the wayside.
An M-98 will run on regulated air down to around 300 to 350 psi, depending on condition (check your hammer O-ring). A good inline reg is a worthwhile, though not necessary, mod. (Automags rarely “froze” from liquid CO2- 90% of the problems people blamed on ‘liquid’ was simply the tank cooling down to the point the tank pressure was lower than the 'Mags internal regulated pressure, leading to recharge problems, inconsistency and other weirdness.)