Mallinckrodt, Inc.

Forma Scientific, Inc.

Russell C Tipton

Glenn D Selfridge

Edmund L Dutton

A safety cabinet having a work area enclosed by a hood structure and including an air circulation and cleaning system. The air circulation and cleaning system includes a plurality of air ducts and passageways through which air is circulated by a blower within the cabinet. A portion of the air exiting the blower is directed through an exhaust after passing through a first filter and the remaining portion of the air exiting the blower is directed through the work area after passing through a second filter. A pressure gauge is connected between the first and second filters for measuring the pressure differential between the two filters to give an indication of the loading and efficiency of the filters. A third filter is disposed upstream of the pressure gauge to remove airborne contaminants in the air flowing to the gauge to prevent such contaminants from leaking from the gauge.

Safety cabinet

A laboratory freezer appliance providing a usable storage space on the order of 5 to 20 cubic feet capable of storage temperatures of -160.degree. C. and lower including an insulated freezer chamber, heat transfer tubes in proximity to the freezer chamber carrying liquid argon at ultra-low temperatures which absorbs heat from the freezer chamber thereby vaporizing the argon in the heat transfer tubes; a closed cycle, hermetically-sealed free piston Stirling cycle heat pump providing a cold end above a vertical displacer driven by a linearly reciprocating piston at a delta T to the freezer chamber of about -13.degree. C.; a condensing chamber surrounding the cold end of the heat pump for condensing argon vapor to the argon liquid; and a distributor for distributing liquid argon from the condensing chamber to the heat transfer tubes and returning argon vapor to the condensing chamber, all without mechanical pumping of the argon, in a continuous, closed cycle refrigeration system.

Laboratory freezer appliance

An incubator for laboratory use which includes a housing defining a thermally insulated inner chamber having a controlled gas atmosphere. Devices for sensing characteristics of the incubator chamber atmosphere, and for conditioning the atmosphere, are positioned in a gas recirculation path outside the incubator chamber. The gas atmosphere of the incubator chamber circulates from a chamber outlet in an upper portion of the chamber, through the recirculation path, returning to the incubator chamber through a chamber inlet in a lower portion of the chamber. Included in the recirculation path are a blower for recirculating the chamber atmosphere, a filter, a CO.sub.2 sensor, and a humidifier. A microprocessor-based controller is responsive to the output of the CO.sub.2 sensor to effect the addition of CO.sub.2 to the recirculating gas to maintain a selected CO.sub.2 level in the chamber atmosphere. Upper and lower diffuser plates in the incubator chamber define upper and lower plenums, respectively. The upper plenum communicates with the chamber outlet, and the lower plenum communicates with the chamber inlet, to produce an upward vertical laminar flow of the gas atmosphere through the chamber. The incubator chamber walls are spaced inwardly from insulated outer walls to provide an enclosed air space about the outside of the chamber wall. Heaters inside the air space, spaced apart from the inner wall, are sized to produce substantially even heating of the chamber through convection in the air space.

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Williamstown, WV, United States of America

Russell C Tipton