Abstract: Method and apparatus for controlling removal of gaseous cryogen from a continuous tunnel type freezer wherein the cryogen and product to be frozen travel in counterflow heat exchange relation to minimize ambient atmosphere moving into the tunnel and out of the exhaust system with the exhausted gaseous cryogen.

Abstract: The present invention is a tunnel freezer which incorporates a "dual flow" design whereby the refrigerant is introduced at each end of the tunnel and withdrawn from the middle of the tunnel. A key to the present invention is that the dual flow design allows one to confine the pressure gradient for leaks between the ends of the tunnel where it will not be a concern since the item entrance and exit ports (which ports provide a ready access for leaks) are located at the ends of the tunnel.

Abstract: A spiral type freezer constructed and operated to introduce refrigerated atmosphere into the bottom of the insulated chamber and circulate the atmosphere in a circulation flow from the bottom of the chamber to an exit on top of the chamber, the refrigerated atmosphere producing a thermal gradient from the bottom to the top of the chamber so that the freezer is operated non-isothermally.

Abstract: Improving the connective heat transfer of a tunnel type cryogenic freezer by positioning the circulating fan blades upside down and closer to the articles moving through the tunnel.

Abstract: Method and apparatus for controlling the cooldown and steady-state operation of a tunnel type cryogenic freezer by providing auxiliary cryogen to one or more gas recirculating zones of the freezer and controlling the supply of the auxiliary cryogen by sensing the temperature of the gas recirculating zone and comparing the temperature to a pre-set level.

Abstract: A method and apparatus for controlling movement of the refrigerated atmosphere (e.g. gaseous cryogen) contained inside the insulated chamber of a spiral type freezer out of, or ambient atmosphere into, the lower opening of the freezer by establishing a positive pressure of ambient atmosphere adjacent the inlet opening of the freezer.

Abstract: Method and apparatus for controlling gaseous cryogen flow through a continuous tunnel type freezer wherein the cryogen and product to be frozen travel in counterflow heat exchange relation to minimize egress of cryogen from, or ingress of ambient air into the product discharge opening in the freezer.

Abstract: A process and apparatus are set forth for a refrigerating or freezing system wherein liquid cryogen, such as liquid air, is fully vaporized during use to avoid dangers of liquid cryogen pooling, liquid cryogen contact with apparatus surfaces or inadvertent oxygen enrichment.

Abstract: In the blasting of articles with impact media, the mixture of used media and fragments of material thereby removed from said articles fall to the bottom of the thermally insulated treating chamber. A method is disclosed for discharging such mixture through an opening in the bottom of the chamber, utilizing a rotating sweeping device having a plurality of sweep arms extending outwardly from a central hub each of the arms being formed of segments to approximate the shape of an ogee curve. Heat leakage into the chamber is minimized by driving the sweeping device from below the bottom of the chamber by an enclosed shaft passed through the insulated bottom of the chamber.

Abstract: Operation of processes for removal of adherent coatings from articles by cryogenic embrittlement of the coatings and blasting of the embrittled coatings with impact media impelled by one or more rotating throwing wheels in a closed treating chamber are disclosed, wherein the chamber is initially cooled down progressively to a supercold preset temperature level considerably below that required for embrittlement of the coatings. In a preferred batch operation the throwing wheel or wheels are rotated in the absence of media fed thereto during an initial stage of the operating cycle. The supercold preset temperature level is controllably maintained for a prefixed time period for prechilling the coated articles. At the end of said prechilling preset time period the blasting of the coated articles is initiated.

Abstract: A cooling and or freezing tunnel is described having a toggle linkage and a pressurized fluid drive to open and close a plurality of openable sections of the tunnel for access and cleaning of the interior. The toggle linkages provide more accurate and reliable movement than the prior art means for opening such tunnels.

Abstract: An exhaust system for a cryogenic freezer is set forth wherein the system senses the temperature of an aperture in the freezer to detect any outward passage of cryogenic vapors and based upon that sensing, controllably operates an exhaust fan to remove such cryogenic vapors.

Abstract: Novel construction is disclosed for a thermally insulated chamber for batch treatment of materials therein at low temperature wherein frequent opening and closing of the outer door of the chamber is practiced. The chamber walls as well as the insulated outer door of the chamber are constructed of rigid but relatively light metallic frames which remain at near ambient temperature. These frames are covered by sheet metal linings on their outer faces and by a plurality of abutting sheet metal inner liners spaced from the outer liners, the space therebetween being filled with insulating material. Buckling and warping of the walls and door as a result of shrinkage is avoided by limiting the maximum linear dimension of each inner liner, by provision of flexible expansion joints in the inner surface and flexible support members which attach the linings to the basic framework, so arranged that paths of only low thermal conductance occur.

Abstract: In the blasting of articles with impact media, the mixture of used media and fragments of material thereby removed from said articles fall to the bottom of the thermally insulated treating chamber. Novel structure is herein disclosed for discharging such mixture through an opening in the bottom of the chamber, utilizing a rotating sweeping device having a plurality of sweep arms extending outwardly from a central hub each of the arms being formed of segments to approximate the shape of an ogee curve. Heat leakage into the chamber is minimized by driving the sweeping device from below the bottom of the chamber by an enclosed shaft passed through the insulated bottom of the chamber.

Abstract: A method is provided for overcoming problems heretofore encountered in systems for continuous cryogenic deflashing of molded articles. Such previous problems include the cracking of the articles as a result of thermal shock suffered by spraying the liquefied gas coolant directly on the article to effect embrittlement of the flash and that of blasting media sticking to the articles. The now disclosed system avoids thermal shock by more gradual cooling of the article and by effecting the desired embrittlement by contact with gaseous coolant obtained by vaporization of the liquefied gas within the treating chamber prior to its contact with the articles. The arrangement of the spray nozzles for the coolant is designed to provide an adequate precooling period to avoid thermal shock and to obtain a temperature profile such that insufficient cooling of the mold release wax is avoided.

Abstract: A quick-coupling device is provided for suspending a rotatable work-holding fixture from a driving device. The driving device is supported from the free end of a cantilever beam attached to the inner face of a door hinged to the framework of a thermally insulated treating cabinet. The driving device has a downwardly extending power take-off shaft terminated in an enlarged plug portion peripherally bevelled to nest in a mating connector affixed to the work-holding fixture thereby forming a friction drive for said fixture. The connector has a C-shaped slot through which the plug can be passed to support the fixture at the nesting mated surfaces. The arrangement is particularly designed for use in impact blasting of coated articles in batch operation, in which the reduced loading time is a highly important consideration.

Abstract: Products to be frozen are conveyed through an insulated horizontal tunnel having a plurality of individual cooling zones, each equipped with a radial fan rotating in a horizontal plane. Cryogenic liquid refrigerant is sprayed into one or more of the cooling zones in the central region of the tunnel, upwardly into the rotating fans and the thus vaporized refrigerant caused to flow in a downward direction in a recirculating pattern into contact with the conveyed products by vertical partitions between contiguous zones. The vaporized refrigerant flows from the supercold zone of liquid introduction beneath the edges of the partitions in two directions, outwardly towards the opposite ends of the tunnel in substantially equal amounts.

Abstract: The temperature actuated valve comprises a thermally more sensitive valve stem than the valve housing. The stem expands at a faster rate and causes vapor entering the valve to be gradually vented through an orifice of gradually increasing area as the temperature of the gas increases. It has application as a cryogenic phase separator valve which allows any cryogen vaporized in a cryogen delivery system to be automatically vented from the valve and to allow for an even flow of liquid to the spray nozzles and onto products of cryogenic freezing tunnels.

Abstract: The temperature actuated valve comprises a thermally more sensitive valve stem than the valve housing. The stem expands at a faster rate and causes vapor entering the valve to be gradually vented through an orifice of gradually increasing area as the temperature of the gas increases. It has application as a cryogenic phase separator valve which allows any cryogen vaporized in a cryogen delivery system to be automatically vented from the valve and to allow for an even flow of liquid to the spray nozzles and onto products of cryogenic freezing tunnels.

Abstract: A carbon dioxide snow generator is disclosed which has a purge conduit for controllably delivering a blast of pressurized fluid at the inner surfaces of the generator to dislodge and remove any residual or clogging deposits of carbon dioxide snow. A vapor loop for such a generator is also disclosed which provides an initial blast of relatively warm carbon dioxide gas at startup which gas entrains and removes any residual liquid before it can freeze in the apparatus.