Glass Heat Exchanger. Any heat exchanger in which glass replaces metal, such as shell-and-tube, cascade, double-pipe, bayonet, and coil exchangers. These heat exchangers, usually manufactured from borosilicate glass, have many desirable characteristics for laboratory applications. They provide long service life, product purity, smooth interior surfaces, and transparency. They are impervious to almost every corrosive and reagent known, are virtually unaffected by heat and thermal expansion, and do not burn or emit toxic fumes.