Abstract: A device for filling a high-pressure CO.sub.2 cylinder with liquid CO.sub.2 while venting gaseous CO.sub.2 comprises a two-compartment chamber that is installed in the top opening of the cylinder. A first dip tube connected to one compartment extends to the bottom portion of the cylinder and a second dip tube connected to the other compartment extends to the upper portion of the cylinder. Each compartment has a port for flow into or out of the compartment. Liquid CO.sub.2 introduced into the compartment with the first dip tube will flow into the cylinder and cause gaseous CO.sub.2 to exit through the second dip tube and the other compartment. When liquid CO.sub.2 appears in the exiting stream, the introduction of liquid CO.sub.2 is stopped. In a common embodiment, a conventional CO.sub.2 valve has the first dip tube connected to the bottom thereof. A street tee with one end connected to the second dip tube is screwed into the top opening of the cylinder. The CO.sub.

Abstract: A positive-acting mechanism for pressurizing a liquid CO.sub.2 storage cylinder involves a sealed tube suspended from the cylinder top and extending down into the bottom of the cylinder. The sealed tube contains an electric heating element and a temperature sensor connected to a thermostat. A pressure-stat with its capillary connected to the top of the cylinder is connected in electrical series with the thermostat. One wire from the heating element goes to a source of electricity and the other to the thermostat or pressure-stat. Another wire to the source of electricity is connected to the thermostat or pressure-stat whichever is not connected to the heating element.

Abstract: A chamber for keeping perishable material, either liquid or solid, under refrigeration is provided with a tubular metal container that can be filled with pressurized liquid carbon dioxide. When the pressure in the container holding liquid carbon dioxide is dropped to atmospheric pressure, approximately half of the liquid flashes off as vapor and half becomes solid. The container is disposed along the top of the chamber so that refrigeration from solid carbon dioxide therein flows through the chamber by convection currents. Carbon dioxide vapor may flow from the container into the chamber to provide a protective atmosphere for the material therein.

Abstract: A device for indicating the level of carbon dioxide snow in the cold box of a refrigerated vehicle comprises three basic elements: a shaft, a disk mounted on an end of the shaft and a bearing to hold the shaft. The bearing is positioned so that the shaft extends vertically through the bottom of the cold box. The disk on the shaft moves up or down within the box by pushing or pulling the bottom end of the shaft. The distance that the shaft is pulled down at time intervals after the box is filled with carbon dioxide snow while the disk was against the top of the box indicates how much the snow level has fallen because of carbon dioxide sublimitation.