Can you heat a co2 ram ?

[grafix]

Andrew, the reason that paintball is going to compressed air at 3500 - 5000 psi is because first, its a consistant shot pattern ( no pressure drop due to cooling gas ) second, quicker recycle or shots ( my electronic marker thats not all that quick fires an accurate 28 balls per second. Co2 cant cycle that quick without makor pressure drop problems ) and thirdly, with one charge I can nearly fight all day passing over 3000 rounds through my marker and whats more, I will still have some air left so that I can clean and test the marker at home and lastly, air is easier to refill that Co2. Its litelally plug and play. Plug it into the air source and watch the pressure gauge.

earlier air bottles were 3500 psi. We now use either 4500 or 5000 psi bottles now.

I hope this explains it for you.

One note, in the early days of Robotwars pneumatics a few people did indeed try compressed air. Paul Cooper from M2 and Technobots for one. But they switched to Co2 due to the higher amount of stored shots. A steel or Ally air bottle would be huge, weighty and very fulnerable. I have a diving bottle at home filled to 5000psi air. I use this to refill at home. This bottle is very heavy.

Regards.

Mike

[maddox]

For paintball CO2 is old hat, not many people are using it anymore, and most of those are the ones who have the kits from earlier days and dont want to spend more cash on an occasional outing.
I think Im the last one still buying CO2 bottles at my local supplier.

The reason most of us started to use CO2 is the 1000psi/70bar rule.
A 3L bottle contains 2 kg of CO2, what means expanded, at room temperature and pressure 1024L of gas.
Thesame bottle filled at the max pressure for robot wars contains 210L of room temp and pressure gas.

This difference is made by the liquifation of CO2 at elevated pressures. But to evaporate that gas you need energy, warmth. In a robot that energy will be taken from the surroundings, and mainly the spots where the gas is expanding/evaporating. With the advent of buffertanks on Full pressure CO2 systems, the bottleneck is most of the times the bottlevalve. But also were the valves/pipes open into the ram.

With the first FP machine I did build, Project2:Hexem I had the bright idea to use 2 bottles, to gain more flow- 2 bottlevalves have better flow than 1. But this caused the feed lines to the valve to frost over, even after the first shot. And the 3/2Woody Valve (the one now used in KaPut) started to chew up the orings inside and therefor getting stuck after a few firings.
My solution in Project2 was to make the feed lines longer and pass over the H7 50W carbulbs that made up her angry red glaring eyes. It helped, but wasnt good enough.
Second machine, Tough As Nails, with almost a simular setup I tried to solve the freezing as light as possible (TAN was from the start on the edge with the weight) And there I opted for the bend up short diptube. This did work, untill TAN gets flipped. Then the liquid CO2 gets in the valving and tubing freezing up everything.
KOS has solved this problem during the years.

Same periode, HARD, less problems due the very small ram, but still frosting of the bottle and tubing.Thanks to the ali finned collector less problems with the small regulator and valve (based on the Woody valve)

The next machine, Gravity in its first incarnation used a hydraulic 3/2 valve and proved less usefull, as the valve leaked internaly.
These machines were participants in the Dutch Series II.

The Gravity III incarnation we have seen in the 7th wars, had the advantage of the learning curve, and a lot of talking over MSN with Woody.
By adding buffertanks, multiple bottles oriented so that liquid wasnt being drawn and Burkert Valves on 36V most problems were solved. The mass of ali in the Bottles, the rather long feed lines to the steel buffertanks and the small diameter but rather long buffertanks gave a lot of surface to exchange warmth from the suroundings into the evaporating CO2.

Andrews Wedgy/Hannibalito2 profit from a few more years of experience.
The bottle feeds an ali finned collector trough a liquid stopper- in effect a flow restriction- but from there on no hole is smaller than 13mm.
Thus the evaporating gas still needs warmth, and when the bottle cools, pressure of the gas drops, lowering the power. And making possible that liquid or solid CO2 forms in the collector, buffertank and so on.

The allowed ways to avoid the cooling problems.
1) lowering the amount of gas evaporated in a certain time. IOW Reducing flow to the ram.
2) More heat exchange surface/more thermal mass.

Disadvantages.
1) Diminishes the power of the system, and that is a waste of weight, as that is better done with a smaller ram.
2) adds more weight in dead weight/space to form the heat exchanger flanges/coils/mass.

[leorcc]

Just knit a woolen sweater for the ram. Problem solved.

[woody]

Mario kindly supplied the ram in Ka-Putt! ... and whilst we both exchange bits /ideas it was to my way of thinking to tight.

The bore is 50mm and the O ring was made by Mario. I replaced this with a smaller section std 50mm o.d. O ring ...this actually floats in the original groove and only seals properly when pressure forces it against the cylinder wall.

[andrewmahoney]

Thought i would pop down to my local gas supplier to buy/rent a co2 bottle to use at home testing wedgie.
Sorry sir,cant do.. (something about back street garages using it for welding)our suppliers wont do small bottles.. ok how much is a big bottle?..about £8 a month.. so thats what im doing after ive filled out the application form in triplicate!
He said.. why not use nitrogen..i can do nitrogen in smaller bottles not as much rent.

So the question is.. can i use nitrogen as a test gas at home and will it do wedgie any harm?(weights/pressures etc)

[john]

i dont no much about what your going on about but im sure nitrogen and co2 are very different?

and if your trying to sort the freezing problem then i guess ud need to test with co2 as thats what is making you freeze

[woody]

Youll need to regulate the pressure of the nitrogen down to less than 1000 psi .....once youve done that you can use nitrogen gas in Wedgie.

[andrewmahoney]

I dont know,just wondering whats the differerence is in a wedgie type system.But you are right,i need to stick with co2 for my problem.

[leorcc]

Nitrogen is not liquid in the bottle, but already gas. Since a similar size bottle can contain more mass in liquid, you get more flips out of a bottle filled with liquid CO2 then you would with 1000psi Nitrogen.

But because you dont have to boil nitrogen, you dont have to draw heat from the surroundings, so no freezing.

[maddox]

In Wedgie a 1000psi Nitrogen filled 12 oz bottle will contain about 33L of gas.
(to fill that bottle with 1000psi nitrogen, youll need a feed bootle-200 or 300 bar nitrogen, a regulator that can achive 1000psi and the connection to a paintball bottle)

That will result in a very powerfull first stroke. But a bottle that is half empty.
Second stroke will be less powerfull and the third, let us say, a limp wrist will do more.