Abstract: A cryogenic liquid is sterilized by passing it through a microporous filter, while subcooling the liquid. Subcooling virtually eliminates the possiblity of formation of gas bubbles in the liquid, and thereby insures that the desired mass flow of liquid, through the filter, will be maintained. The apparatus used with this invention comprises an insulated tank, filled with cryogenic liquid. A container having a microporous filter disposed therein, is submerged within the tank. The filter can be made of nylon mesh, which is encased within a polypropylene frame. The filter has a pore size of about 0.2 microns or less. The liquid to be sterilized is a saturated cryogenic liquid. The liquid in the tank is held at a temperature lower than that of the liquid to be sterilized, and therefore subcools the liquid being sterilized. The sterilized liquid is then withdrawn directly from the filter container.

Abstract: A vacuum furnace is cooled in a two-step process. In the first step, a noble gas is injected into the furnace to break the vacuum, and to provide initial cooling. In the second step, a non-noble, but relatively inert, gas is injected into the furnace to complete the cooling. The flow of the noble gas is cut off when the temperature in the furnace falls below the point at which the contents of the furnace will no longer react with the second gas. The invention also discloses apparatus for cooling the furnace. Temperature controllers monitor the temperature, and rate of temperature change, in the furnace, and direct controlled amounts of noble or non-noble gas into the furnace. At no time is a liquefied gas allowed to enter the furnace. The process allows the furnace to be cooled rapidly but safely, minimizing the danger of thermal shock to the internal furnace components.

Abstract: A process for removing layers of paint or other non-metallic coatings from a coated metal hanger or the like comprising the steps of freezing the coating to embrittle it and shrink it toward the metal hanger, heating the metal hanger without heating the coating to expand the metal toward the coating, and stressing the coating by said expanding and shrinking to break and fragment the coating and cause it to fall off the metal hanger.

Abstract: A vacuum furnace is cooled in a two-step process. In the first step, a noble gas is injected into the furnace to break the vacuum, and to provide initial cooling. In the second step, a non-noble, but relatively inert, gas is injected into the furnace to complete the cooling. The flow of the noble gas is cut off when the temperature in the furnace falls below the point at which the contents of the furnace will no longer react with the second gas. The invention also discloses apparatus for cooling the furnace. Temperature controllers monitor the temperature, and rate of temperature change, in the furnace, and direct controlled amounts of noble or non-noble gas into the furnace. At no time is a liquefied gas allowed to enter the furnace. The process allows the furnace to be cooled rapidly but safely, minimizing the danger of thermal shock to the internal furnace components.

Abstract: The invention includes a method and apparatus for providing a sterilized cryogenic liquid. A cryogenic liquid is vaporized, and the resulting gas is sterilized. The sterilized gas is then reliquefied and subcooled. The liquid is vaporized by passing the liquid through a heat exchanger, heat being transferred from the previously sterilized gas to the incoming liquid. Sterilization is accomplished either by passing the gas through a microporous filter, or by subjecting the gas to ultraviolet radiation. The sterilized gas, after passing through the heat exchanger, is directed into a pressurized container, wherein the gas is reliquefied and subcooled. The subcooled liquid is then withdrawn from the apparatus.

Abstract: A low pressure delivery system for cryogenic liquids is disclosed, the system being capable of providing a stream of a single-phase cryogenic liquid at a substantially constant low pressure, in the range of about 1 psi. The system comprises a container into which a cryogenic liquid, from a high pressure source, is directed. The liquid in the container is maintained at a substantially constant level by an automatic filling mechanism. The liquid does not occupy all the space within the container, the remainder of the space being filled by gas evaporating from the liquid. This gas communicates, by a suitable conduit, with a pressure regulator valve. When the gas pressure exceeds a predetermined level, the valve opens, relieving the excess pressure. By thus placing an upper bound on the gas pressure, the system places an upper bound on the pressure of the liquid withdrawn from the container. The automatic filling mechanism of the system establishes a lower bound on the liquid pressure.

Abstract: A method and apparatus for expanding a length of flexible tubing so it can be placed over a cylindrically shaped member which has an outside diameter larger than the inside diameter of the tubing. This is accomplished by first expanding the flexible tubing mechanically with a flexible cage and mandrel to the desired inside diameter and then freezing it at this expanded size by spraying it with a cooling media such as liquid nitrogen. The frozen expanded tube can then be easily placed over the cylindrically shaped member so that when the expanded tubing warms and returns to its original configuration, it will generate a tight pressure bond to the inserted member.

Abstract: A system for delivering cryogenic liquids at controlled low pressures is disclosed, wherein the liquid is withdrawn from the bottom of a container, and allowed to flow by gravity to the point of use. The system comprises an inlet conduit which directs a liquid cryogen into the container. The inlet conduit is connected to a float valve assembly which regulates the height of the liquid in the container. The vertical position of the float valve assembly is adjustable. The liquid cryogen is withdrawn from the bottom of the container, through an insulated outlet conduit. The pressure of the output liquid is determined by the vertical distance between the lower end of the outlet conduit and the liquid level in the container. Adjustment of the position of the float valve assembly therefore controls the output pressure. Gas bubbles that may form in the liquid tend to rise to the top of the container, so that the output is of a single phase, that is, an essentially pure liquid.