Abstract: An apparatus for cooling or freezing articles in which the articles are moved through a tunnel and are contacted successively by a vaporized cryogenic medium and liquid cryogenic medium. Jets of pressurized gas are introduced into the gas contacting zone to cause turbulence in flow of vaporized cryogenic medium through that zone.

Abstract: The invention provides a method for producing oxygen-enriched air for respiration which method utilizes an apparatus which comprises at least one bed containing an adsorbent which preferentially adsorbs nitrogen from air, an air inlet at one end of the bed, an oxygen-enriched air product outlet line connected to the other end of the bed, a reservoir in the outlet line for storing pressurized product gas, a pressure regulator located in the outlet line downstream of the reservoir and adapted to regulate the pressure of product gas in the outlet line downstream of the regulator to a predetermined value, a restriction device located in the portion of the outlet line between the bed and the reservoir to control gas flow in such portion of the outlet line, a valved vent line from the air inlet end of the, or each, bed to permit release of any superatmospheric pressure in such bed and a valved line leading from the air inlet end of the, or each, bed to a vacuum pump to permit evacuation of such bed.

Abstract: A process for arc welding in an underwater environment wherein a welding chamber is positioned adjacent a workpiece and an arc welding torch is positioned therein. A gas under pressure is introduced into the chamber to displace the water and a gas is supplied to the torch at a pressure greater than the pressure of the gas in the chamber.

Abstract: A soluble gas such as oxygen is dissolved in a liquid such as aqueous sewage liquors by introducing the gas into a stream of the liquid and passing the resultant stream downwards into a body of the liquid through a conduit of divergent cross-section in the direction of flow of the liquid.

Abstract: Underwater welding apparatus including a welding chamber and at least one source of gas under pressure connected to the welding chamber through a demand valve, in which the demand valve allows the flow of gas to the chamber to increase as the increase in the hydrostatic head causes the pressure of the gas in the chamber to increase, and to decrease as the hydrostatic head decreases.

Abstract: An oxygenation system for promoting the activity of microorganisms supported on a filter bed, by introducing an oxygenated liquid stream into contact with the microorganisms.