Folks don't know why it popped into my head but here goes

Given that compressed CO2 is a liquid - what happens when you shoot 'up hill'?

Does the firing mechanism flood with liquid and does it even care?

Anyone know the differences and effect of shooting up, or down, hill versus on the level?

No reason for asking, just curious

thanks!

A CO2 cylinder, when new, contains a mixture of liquid and gaseous carbon dioxide. The pressure of the gaseous CO2 above the liquid CO2 is called the vapor pressure of CO2 and is a property of the liquid and a function of temperature. At any given temperature, the vapor pressure of CO2 remains constant as long as there is some liquid CO2 still in the cylinder.

CO2 is most stable in the gaseous state at normal room conditions -- approximately 1 atm and 20ēC (68 F)

IE: as temperature degreases......CO2 pressure decreases.....and your rifle muzzle velocity drops..
...as temperature increases, CO2 pressure increases..and your rifle muzzle velocity increases..

At lower temperatures,you may see CO2 vapor exit barrel....not liquid..

...between 60 F and 90F, you will not see big POI changes...

CO2 Liquid/Vapor phase:
90 F....1200 psi
80 F....969 psi.
70 F....853 psi
60 F....747 psi
50 F....652 psi
40 F....567 psi
30 F....491 psi
20 F....422 psi
10 F....361 psi
0 F.....306 psi

For shooting uphill/down hill,only effect is trajectory :

Airgunners Rule...If the angle is less than 20 degrees or the distance is less than 20 yards,shoot for the center.
Otherwise,aim for the bottom of the kill zone.

Great post Rich, good info. thanks +5 for you

The 850 Store

I've researched this and done some testing so thought info would be useful...

Thanks for the info, useful stuff - it is getting a bit chilly in Blighty now so let's see how it affects the shooting!

But, to be obtuse, I was actually wondering what the effect of radical elevation would be so here's the simplified, extreme question.

If you shoot straight up i.e. vertical then you'll be charging the chamber with liquid? (I guess??) so does it matter.

Contrary wise, if you shoot directly down you'll be sucking vapour only so does that matter either?

I was looking at advice on recharging bulk C02 (i.e 'pour' it in) when it dawned on me that it's actually a liquid (duh)and the up/down orientation may cause issues at extremes.

May seem a bit odd but I've got firing options of shooting up at pigeons or down on them so advice and experience gratefully received.

Obviously for HPA (or springers - bless 'em) it matters not a jot.

Apologies for the tardy response but work has me travelling all over at the moment and forum browsing has been somewhat limited

Thanks all

Lawrence

The truth is that it does not make a huge difference.
The liquid being pushed into the valve after an up hill shot, cooks off
very rapidly as it enters the low pressure area and as it becomes vapor,
sort of like a bubble, it prevents any more liquid from entering the chamber.
Although we open up the channel between the tank and the valve to facilitate
better flow, its still small enough to prevent pure liquid to fill the valve.
When it gets colder it is true that you will get some liquid in the valve, but
the amount is small enough not to cause too much trouble, other than slowing
things down a bit.
This is why CO2 is better suited for the warmer months of the year or places
like Hawaii where its warm all year

P.S. There are no "silly" questions on this forum. It's silly not to ask

The 850 Store

thanks, excellent explanation. I'll give it a go to see if I notice any difference.

Out of gas now, so gotta get back on Ebay and buy another 5 pack

That HPA conversion looks more and more enticing as I tot up the costs of these 88g cylinders.

Think I'll add to my Santa list

rgds

Lawrence

PS rest assured, I'm certain to have some more silly questions for y'all

The colder is gets the less pressure differential there is between the liquid and the vapor state,
so it'll "cook off" slower. This will allow more liquid to enter the valve the colder it gets.

On a hot day 80deg F or above, the transision to vapor is so rapid that the the valve will
fill with vapor so rapidly that it prevents liquid from following. At those temps the vapor is 
at over 1000psi where as in winter around 45deg F the pressures is only around 600psi   
Its a bit of a moving target, thats what makes it difficult to tune for.

You could think about refilling your own CO canisters, it works out a lot cheaper that way.


The 850 Store

lawrence

if your out in field over winter when the light is failing then co2 is complete crap over here in the u.k

if you plan on doing any modding to the 850 convert to hpa it might seem more expensive than buying say an s410 new but you always have the option of back to co2 for plinking in the garden for practice.

roalds kit is very well thought out and will give you the option of a duel fuel rifle if such a thing exists

just my five pennies worth

simon