How to Create a Vacuum in a Bell Jar

Bell jars are designed to be unbreakable chambers used to create vacuums for scientific experimentation and exhibition. Originally, bell jars were made from heavy glass, but many modern bell jars are made from polycarbonate. They include a vacuum plate that is used with a hand pump to create a vacuum in the jar. Items, such as balloons, candles and bread can be put in the jar before the vacuum is created to demonstrate different properties of a vacuum. Bell jars can be purchased from science specialty retailers, some school product suppliers and many online retailers. They can also be found in almost any high school or university science lab.

Things You'll Need

• Bell jar
• Vacuum plate
• Hand pump

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Instructions

1. • 1

     Put anything you will be experimenting with into the jar.

   • 2

     Put the vacuum plate on a flat surface to ensure the best seal. Place the jar into the gasket on the vacuum plate. Older bell jars with worn gaskets may require a thin strip of petroleum jelly or other grease around the jar base to maintain a proper vacuum.

   • 3

     Locate the 1/4-inch tubing extending from the vacuum plate. Connect the open end of the tubing to the nozzle on the hand pump.

   • 4

     Pump the hand pump until the pressure gauge on the plate indicates a pressure of approximately 20 negative pounds of pressure.

   • 5

     Note any changes to the items inside the jar.