Abstract: A sensor or regulator capable of operating at high absolute pressures and for measurement of pressure, especially pressure differential, or liquid level, is disclosed and has a member which moves in response to pressure differential and being coupled directly to a diaphragm via a lever linkage or which is displaceable by a float and which is juxtaposed with an inductive proximity switch responsive to movement of the member where the proximity switch can be mounted directly in a pressure-retentive wall, a sight glass or like pressurizable partition partition need not be provided. In the preferred construction, however, such a glass, sealed in the pressure wall of the housing, is interposed between the inductive proximity switch and the movable member to which that proximity switch responds. A method of controlling oil/refrigerant mixtures in a refrigerating plant is also disclosed.

Abstract: A heat exchanger designed to cool a liquid such as water has a boiler with several upright heat-transfer tubes on whose inner surfaces the liquid descends in the form of a thin film while a refrigerant such as ammonia or a Freon rises within the boiler. To generate the thin films the liquid to be cooled is collected in a storage vessel above the boiler into which the heat-transfer tubes project. Each of these open-topped tubes contains an insert with a frustoconically diverging bottom part approaching the inner tube surface to within a fraction of a millimeter. The bottom part of the insert has an acute-angled peripheral edge insuring the detachment of the liquid from its surface. The several inserts are suspended from a vertically reciprocable piston rod forming part of a pneumatic jack whose alternate pressurization is controlled by a relay in response to two microswitches actuated by cams on the piston rod and to two level sensors ascertaining the liquid level in the storage vessel.