Improvements relating to hypodermic syringes

Abstract

Abstract A piston for a hypodermic syringe, preferably having a glass barrel, is formed of a ceramic material (e.g. a porcelain having a coefficient of expansion substantially equal to that of the glass) and contains an insert of moulded metal or plastic material inserted in a cavity in the back of the piston after the latter has been fixed, the insert serving for the fixing of the piston rod. The insert, which may be formed with an internal or external screw thread for screwing the piston rod thereto and may be of hexagonal shape or have ribs to prevent the turning thereof in the cavity is keyed into position by means of recesses such as undercuts or screwthreads. Where the insert is of metal a coating of a rubber-like material resistant to high temperatures, e.g. a silicone, may be interposed between the piston and the insert.

Inventors

No inventors recorded.

Bibliographic Details