Fire Piston
Demonstration Unit
"The Pyro Piston"
(AS SEEN IN POPULAR MECHANICS - APRIL
2010 issue)
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A dramatic
example of Boyles' Law!
A ready-to-use fascinating apparatus to
demonstrate how temperature increases with
pressure by igniting cotton tinder as the plunger
compresses air in a cylinder.
A heavy aluminum rod fits inside a clear acrylic
tube. A piston tipped with three O-rings and
fitted with a contoured handle is used to compress
rapidly the gas, raising the temperature
sufficiently to ignite a small piece of paper in
the tube.
Technical Analysis of What is Happening
(Classroom Lesson)
Our classroom
Fire Piston Demonstration Unit is a classic
example of Boyle's Law (PV=nRT). By compressing
the air in the cylinder into a smaller volume, we
are also increasing the temperature inside the
cylinder. Looking at the components of the
formula, a large increase in P (Pressure), results
from a significant reduction in V (Volume), with n
and R being constant, that leads to a large
increase in T (Temperature) which will ignite the
cotton tinder in the cylinder.
Unit
Includes...
- Machined aluminum piston plunger
(will last for years)
- Clear Lexan piston chamber ( so you can
easily "see" the combustion reaction)
- Replacement gasket o-rings (replacement
parts for the future)
- Cotton tinder (included material to start
the demos immediately)
- Complete instructions (to insure your
success at using the unit)
How to Use
1. The setup is quick and easy. Pull out the
plunger, drop in a small piece of the cotton
tinder.
2. Re-insert the
plunger gently so that it just enters the mouth of
the piston chamber.
3. Holding the
unit flat on a non-slip surface, push down the
plunger with some force and speed. You will see a
flash of fire inside the clear Lexan
tube as the air is compressed, heated to a point
that ignites the cotton tinder. The combustion
will last until all available oxygen in the
cylinder is used up.
How it works:
Air gets very hot when compressed under high
pressure. If you have ever pumped up a bicycle
tire, you have noticed the heat generated. The
Unit has a "compression ratio" of approx. 18:1
(the volume of cylinder is 9ml and reduces to .5
ml when the plunger is compressed).
When the air in
the Fire Piston Demo Unit is compressed, it is
done so fast and efficiently that it results in a
temperature increase to well over 210oC
(378oF), the "flash ignition
temperature" of cotton. In fact it can reach
instantaneous temperature of over 260oC
(500o F) inside the cylinder!
Maintenance
Your plunger has been pre-lubricated and should
not need additional lubricant for sometime,
however additional lubricant is included with the
unit.
After each use,
clean out the cylinder with a wooden stick or
simply blow out the carbon dust from the small
fire you just made. The Demo Unit is ready to use
again.
Price
$55.00
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