Maurice C Green

US Patent:

42177987, Aug 19, 1980

Filed:

Apr 30, 1979

Appl. No.:

6/034560

Inventors:

Charles J. McCarthy - Rockville MD
Maurice Green - Silver Spring MD

Assignee:

The United States of America as represented by the Department of Health,
Education and Welfare - Washington DC

International Classification:

B67B 708

US Classification:

81 32

Abstract:

A device for removing the stopper from the top of a test tube without exposing the user to hazardous aerosols. The stoppered test tube is inserted upwardly through a vertical passage leading to a chamber. A horizontal air cylinder has a piston rod extending into the chamber, with a pivoted stopper-removing plunger member extending over the passage and having a tail portion which is sealingly engageable with a normally vented sensor nozzle responsive to contact of the top of the stoppered test tube with the plunger member. Closure of the sensor nozzle activates a fluidic back pressure switch, which in turn actuates a fluidic control circuit having two slide valves which respectively operates the air cylinder and simultaneously connects a vacuum source to the chamber. A horizontal slide sensor in the vertical passage is extended to engage the test tube and prevents retraction of the plunger member. Upon withdrawal of the unstoppered test tube, the slide sensor is released and is further extended, causing resetting of the fluidic control circuit to its normal condition, retraction of the plunger member, venting of the sensor nozzle, and retraction of the slide sensor.