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[at-l] Re: fuel bottles & FILL LINE

I think Benjamin Brent Forbis is on the right track with his reply, but
may I add my 2cents?

A gas (air space, not liquid) is relativly easy to compress to a higher
atmospheric pressure.  On the other hand a liquid will compress very
little.  In the application of the stove, if there is little "air space"
inside that will be pressurized, then the pressure will build quickly
with a few strokes of the pump, but also when using the stove, the
pressure will drop very fast and it will go out in quick order.  

 As the fuel is used up and the tank gets empty, it is easier to pump up
the pressure, but takes longer to feel the same degree of effort or
pressure.  It took longer to compress the gas.  It will then take longer
to release the gas (pressure) and thus the stove will burn longer for the
same pressure as the compressed gas will continue to expand much longer.

The size of the air colume (empty space) inside the fuel tank is
proportional to how long the stove will burn with a pressurization (you
pump it) to a fixed value.  If you fill the fuel bottle and leave no
empty space, the bottle will pressurize in a few strokes and burn for a
few seconds or minute and die.

Another reason for space in the container is expansion.  As you hike up
hill, the outside atmospheric pressure drops, but the pressure inside the
bottle remains, and being higher there is the chance of a leakinto your
pack.   The pressure also will change with temperature.  As fuel gets
hotter it will expand during the day.  If there is no air space to easily
absorb the fuel expansion, the pressure will climb higher and then it
will leak also.

The bottom line on the FILL LINE.  The manufacture figured it needs this
much compressable air space to function to your reasonable expectations. 
Do you want to be happy?

Peter Lascell
Forest, VA

On Thu, 30 Jan 1997 13:02:45 -0500 "Benjamin Brent Forbis"
<bbforbis@eos.ncsu.edu> writes:
>	The principle behind the space in the bottle is that it allows 
>room for
>the bottle to be pressurized. In order to convert the liquid to vapor 
>so you
>get a cleaner more effficient burn the system(bottle) has to be 
>pressurized to
>vapor. Without adequate room in the bottle to pressurize it so that 
>vapor forms
>your burn more liquid than vapor and will therefore burn more fuel

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