| 摘要 |
A method of making level vials includes the steps of heating a hollow glass tube and inserting the heated glass tube to a mold having a plurality of successively arranged mold cavities, each configured to the shape of one level vial having an enlarged, bulbous-shaped central portion and two circular cross-sectional end portions. Next, one end of the glass tube is removably sealed and a pressurized fluid, such as air, is injected into the opposite end of the glass tube, causing the heated glass tube to expand into contact with the walls of the mold cavities to form a plurality of connected vial sections. Apertures are formed, such as by drilling, in each vial section for subsequent filling of each vial with a liquid and a gaseous level indicating bubble. Each vial section is separated by a cutter and the ends of each vial section are sealed by heat from a heat source.
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