Glass tube

Glass tubes or glass tubing are hollow pieces of borosilicate glass used in laboratory glassware. They are commercially available in various thicknesses and lengths, according to known standards.

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Glass tubes can be cut by scoring with a diamond cutter, and bending, giving a break with a clean edge. The ends are preferably flame polished before use to remove the edge. Hose barbs can be added to give a better grip and seal when used with rubber tubing. Glass tubes can be bent by heating to red heat in a non-luminous Bunsen flame. The glass tubes are fitted to rubber bungs by drilled holes.

In the past, scientists constructed their own laboratory apparatus prior to the ubiquity of interchangeable ground glass joints. Today, commercially available parts connected by ground glass joints are preferred; where specialized glassware are required, they are made to measure using commercially available glass tubes by specialist glassblowers. For example, a Schlenk line is made of two large glass tubes, connected by stopcocks and smaller glass tubes, which are further connected to rubber hoses.