Demos: 3E-03 Fire Syringe

Rapid adiabatic compression causes a rapid rise in temperature in a chamber of confined air. The temperature reached is sufficient to initiate combustion of a flammable material.

Directions: A small amount of combustible material is placed in the bottom of a thick-walled glass tube. Insert the piston and with the lights dimmed in the room, drive the piston downward into the tube with a rapid, forceful stroke. (You may need to do this a couple of times.) If done properly, the material in the tube will ignite, creating a brilliant flash of light in the tube. (You might wish to practice this ahead of time to make sure it works. It is very reliable, so the success rate is high.)

Suggestions for Presentation: Discuss adiabatic compression as it relates to Diesel engines. Explain that the rapid compression raises the air temperature in the cylinder to the ignition temperature of the Diesel fuel. Then simulate this by performing the fire syringe demo.

Applications: Diesel engines. Of interest to the students might be a story published a few years back about an archeological discovery in South America. In an ancient native village site, a large stone was found to have smooth holes bored into it, and these holes contained smudge marks. Speculation is that by inserting tight-fitting (wooden?) cylinders and rapidly plunging them into the holes, a fire could be started.

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Last Updated: May 9, 2016 11:44 AM