Propane powered pneumatic

POLAND_SPUD · Tue May 19, 2009 12:30 am

do what tech wrote

or/and you could use a bigger tank - that should help to some extent but still it will get cool after a while

I know that heating a tank does seem a little bit dangerous... I am not saying that you should heat the tank with a flame
(but it's not as stupid and dangerous as you might think it is - if the pressure inside the tank is within rating of the tank there shouldn't be any problems... of course if you can do it in a controlled manner and you made sure the flame won't reach the hose or something like that - I am just trying to point out that it is possible to do it and it doesn't equal = suicide)

Technician1002 · Tue May 19, 2009 4:40 am

POLAND_SPUD wrote:do what tech wrote

or/and you could use a bigger tank - that should help to some extent but still it will get cool after a while

I know that heating a tank does seem a little bit dangerous... I am not saying that you should heat the tank with a flame
(but it's not as stupid and dangerous as you might think it is - if the pressure inside the tank is within rating of the tank there shouldn't be any problems... of course if you can do it in a controlled manner and you made sure the flame won't reach the hose or something like that - I am just trying to point out that it is possible to do it and it doesn't equal = suicide)

Not heating the tank with a flame is for safety reasons. Warm water doesn't overheat when unattended or not watched closely and it doesn't set the burst or leaking connection on fire.

When doing air conditioning service, the bulk tank is often kept warm in water to fill a system in a reasonable amount of time. Delivering liquid is avoided to prevent damage to the compressor. Propane as a refrigerant can use the warm bath to keep delivery pressure up.

boom_o_matic_2.0 · Tue May 19, 2009 9:59 am

Last night I started brain storming it and came up with an idea.
I have an old pressure cooker somewhere. I could put a coil of copper tube into the cooker then fill it with water. have my propane running through the tube.

Biopyro · Tue May 19, 2009 10:16 am

It'd work, but it still carries the risk of ignition of leaks.
Also, it might actually encourage delivery temperature (and so, pressure) to be above standard levels.

You could just use an expansion chamber, then your firing chamber. There would only be liquid in the expansion chamber, so that would be very cold, but you would still get a high pressure. Your flow wouldn't be excellent though. I suppose your solution depends on the portability you want...

jimmy101 · Tue May 19, 2009 10:52 am

Nope, really won't work. Just dropping the propane tank in an unheated bucket of water will work better.

You need to get heat into the liquid propane. Adding heat to the already gaseous propane won't do much. It won't increase the pressure in the system since that is controlled by the temperature of the liquid in the resevoir.

Heat transfer via the gas from the heater back to the liquid in the tank will be very inefficient. So the heater won't do much of anything to the propane resevoir.

To make it work as drawn you would need to invert the propane tank and feed liquid propane into the coils. Even then the pressure in the system will still tend to be regulated primarily by the temperature of the liquid propane in the tank and not by the temperature of the coil. All you would accomplish is that the system would supply gas faster but the pressure would still be based on the temperature of the liquid in the tank.

Moonbogg · Tue May 19, 2009 11:58 am

I went camping and in the morning my propane was so cold it couldn't give any pressure, so, when noone was looking, I stuck the tank in the community coffee pot! It worked like a charm and I suggest you do the same.

POLAND_SPUD · Tue May 19, 2009 2:51 pm

well I am no saying it's a perfectly wise thing to do... but don't believe that it's insanely dangerous...

my point is that there are hardly any ways in which you can heat the tank that won't increase the mass to a great extent... as tech said immersing hte whole tank in water will work - but since the gun will to use propane it's tempting to use some of it to heat propane

again that's just a suggestion... you'd need to find a good and safe way to do it

deathbyDWV · Tue May 19, 2009 3:28 pm

So do you have to dunk the tank in coffee?!?! JK

I really think the water idea is the best. If i saw some one heating a propane tank with a fire i would kinda say, Oh thats cool... just let me get behind this barracade before you do that!!!

POLAND_SPUD · Tue May 19, 2009 4:20 pm

well yeah I think I would do the same...

but I am aware that it's not as dangerous as it seems.. as long as the pressure stays below raitng of the tank, and you make sure that you won't burn the hose you should be find... let's face it even if the valve on the tank leaked (it shouldn't) it won't cause an explosion and it would require quite a big flame + long time to casue rupture of the tank

I know it does seem dangerous.. there is something inbuilt in our minds that tells us it's not a good idea... but in fact it isn't as dangerous as not checking the seals on the tank that you put in your house/camper (after each refill the seals should be replaced - the guys refilling the tank are supposed to do it... )

someone wants to use propane for portability... but he can either use a bigger tank or heat the tank to replace heat removed by evaporation of propane.... there are no simple ways of doing it that won't increase the mass of the launcher

spudmanb3 · Tue May 19, 2009 8:16 pm

I think (Don't Trust me) That propane is generally around 120-150psi in the bottle. Again, don't trust me.
-James

Technician1002 · Tue May 19, 2009 9:46 pm

spudmanb3 wrote:I think (Don't Trust me) That propane is generally around 120-150psi in the bottle. Again, don't trust me.
-James

The data is easy to find online. Here is a vapor pressure graph I just snagged. The pressure is directly related to the temperature.

jimmy101 · Thu May 21, 2009 1:29 pm

Technician1002 wrote:
spudmanb3 wrote:I think (Don't Trust me) That propane is generally around 120-150psi in the bottle. Again, don't trust me.
-James
The data is easy to find online. Here is a vapor pressure graph I just snagged. The pressure is directly related to the temperature.

Or, you could just use the graph in the SpudWiki page on Propane;