What Happens When You Vacuum Glass?


Bell jars are used in educational and professional laboratories to display scientific demonstrations and experiments. An exceptionally fantastic fact about Tempered vacuum glazing.

Glass bell jars offer an economical and flexible means of creating vacuum chambers, ideal for many purposes such as degassing, drying, impregnation, and encapsulation.


A vacuum glass bell jar is designed to contain vacuum pressures. They feature thick rims of glass that have been cut and ground smooth to provide an airtight seal and ensure vacuum retention.

Bell jars typically feature a precision ground flange bottom and a knob at the top for easier manual manipulation. They are also available with either a standard round or dome top.

Bell jars are constructed using borosilicate glass, fire-polished, and ground at their open ends before being fully annealed after production.

Water balloon models can be an excellent way to demonstrate how a water balloon will disintegrate under a high vacuum or how water boils at room temperature, among many other phenomena. Ideal for both educational and professional laboratories, but always check carefully for damage before use.

Bell jars can be equipped with an implosion guard to shield glass flasks from being hit with flying shards during an implosion, as well as being fitted with a bell jar cage that provides additional protection from contact with pressurized jars.


Vacuum glass bell jars are constructed to be safe at vacuum pressures and of the highest quality borosilicate glass for your safety and convenience. Available in various sizes and configurations to meet your specific needs.

Standard options for glass jars include a ground flat flange bottom and knob on top for easier manual manipulation, with some accommodating rubber stoppers within their dome radius for additional security.

Bell jars can be used with a base plate to create and sustain a low-pressure environment for laboratory experiments. In addition, their optical clarity makes them easy to view during experimentation.

Bell jars feature a neoprene gasket to seal against their bases and can come equipped with tubing adapters to connect to vacuum pumps. Primarily intended for low-pressure vacuum applications, these bell jars can be handled via lift rings or handles and coated with silicone vacuum greases to improve sealing between the bell jars and base plates, helping prevent sagging or movement during handling.


A vacuum glass bell jar is laboratory equipment used to generate vacuum conditions in an enclosed environment, typically on a base that vents to an outlet hose fitting and is connected by hose to a vacuum pump.

This instrument can be used to demonstrate various physical phenomena, including soundwave propagation in air, for classroom demonstrations and professional laboratories.

This lab-grade glass jar features a knobbed glass stopper to create a vacuum. This can also be used to demonstrate water boiling at room temperature.

These vacuum chambers provide an economical and versatile means of creating an all-vision section, perfect for degassing or vacuum testing when high-quality vacuum levels are necessary. Jars come in various diameters and lengths and can be combined with our Baseplates or Feedthrough Collars for optimal use.


Chemists using flasks of one-liter capacity should always employ a safety screen or the sash of a flow hood to avoid glass fragments being expelled into the atmosphere when their vessel implodes under vacuum pressure.

These precautions are necessary when using vacuum glass bell jars in educational and professional laboratories since these jars are composed of thick glass several millimeters wide with a high sealing flange to enhance sealing power and a sturdy knob to hold onto.

Bell jars can create controlled environments for low (coarse vacuum) and acceptable vacuum range experiments. Press it against a vacuum experiment plate until enough air pressure builds against its rubber seal, and release after several minutes.

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