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C02 pressure spikes
WARRAVEN:
Hello! I actually want to ask a question for a little tid bit of research I want to do. I am a writer for a paintball magazine, and I wish to do an article on the diference between Compressed air and C02. I have taken only a college introductory level of chemistry and an honors level high school chemistry course. I was wondering if anyone could help me find the best way to visually show the pressure, and velocity spikes that would occur due to the C02 being compressed and over several diferent temperatures.
I have some information(like pressure at a certain temperature, size of the container and all that), and I was going to use the ideal gas constant equation, but I realized that that wouldn't show the inefficiency I wish to show.
Or if anyone else has any ideas I'd be glad to listen to them. Also, if I do use the help I get from here, I will be sure to mention my thanks in the article itself :) .
I also know many things already, so don't feel like you have to give me other things, I'm just wondering about showing the velocity spikes graphically(just so noone gets confused or anything like that). Thankyou!
Raven 8)
billnotgatez:
Raven - When you publish your article please post where we can read it here. It seems very interesting.
It seems to me (and I could be wrong) that for the pressures and temperatures you will be operating at - you can use the universal gas equation / ideal gas law and not need Van der Waals equation. You might want to consider discussing the triple point of Carbon Dioxide (it sublimes at standard temperature and pressure). Also remember that air is the combination of the partial pressures of all its constituents. Since I am only interested in atmospheric Carbon Dioxide, I can not be of much more help unless I study it more. You might try
http://en.wikipedia.org/wiki/Main_Page
and search Ideal Gas Laws.
By the way what do you mean by velocity spikes?
This is something I ran across that I use
http://www.digitaldutch.com/atmoscalc/
when dealing with atmospheric stuff
Notes to the administrators – when you moved this item from where it was originally posted I think that a more appropriate place could have been selected. For instance, you might have chosen physical chemistry or general chemistry. Then someone with expertise would see this question.
Regards,
Bill
Donaldson Tan:
I move the topic here.
Isn't this a physics problem?
WARRAVEN:
I thought it was an analysis thing. I was using the ideal gas law, I graphed it, but I havn't tried the Compressed air in the equation yet. Well, heres the problem with C02 being used as a compressed gas.
The problem is that it goes into its liquid form too readily. When you try to pull it out at a regular pressure, you pull out a lot of liquid too, which causes velocity spikes, and if your using regulators, you freeze them(which is not good at all). This is why C02 requires a few things, like anti-siphon tubes, and expansion chambers(a chamber system used between the ASA and the marker to allow the C02 expand) and most times you still get liquid C02, which can cause problems on a paintball marker. Compressed air however, is almost completely a gas when confined(its three point is spread out, so it takes a LOT of pressure to get it as a liquid), which means you can pull out of it an exact pressure, without liquid in there to throw off the pressure(since liquid is a diferent weight/size than gas).
Also, with changes in temperature during the day, C02 can be thrown around its stages quite frequently, this means that the settings get thrown off a lot as well, and that you then get oddjumps in pressure. I was just hoping that I could somehow show this more graphically... not that I need to, but if I can, I want to try... and because I actually like doing this for some wierd wierd reason(next year I hope to go to college for this type of thing). Any ideas? I only did C02 using the ideal gas law(I had pressure and volume at a certain temperature, so I used PV=nRT and found n, which I could then change the temperature and leave Pressure as a variable), and the increase seemed quite steady, but I havn't done CA yet.
I did C02 over 10 degrees(from 78 to 89 degrees fahrenheight, which needed converting to Kelvin). I'll try CA in a little. And I have to go take my car somewhere, but I'll check some of my books for van der waals, I remebmer his principles and forces, but the equation is blowing my mind. Thanks again!
Raven 8)
Demotivator:
I believe it is the wrong track trying to explain this through the ideal gas equation (although ideal graph can be used as a reference). If air and CO2 were ideal, they would behave exactly the same, which obviously isn't the case. Van der Waals equation is more appropriate.
This article is pretty good in applying Van der Waals to different gases in another apllication, illustrating differences. The examples illustrate pressure/vol but pressure/temp can also be drawn. It also is handy in providing the a, b constants for different gases, including air and CO2 (a is much larger for CO2 than the other gases).
http://www.babilim.co.uk/pages/gas_laws.html
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