Cryogen delivery apparatus.

摘要

An apparatus includes a pressure vessel 10 in which a cryogen 16 is received and a liquid-vapor interface 20 is maintained so that a gaseous form of the cryogen having a low cooling potential is situated above the liquid-vapor interface 20 and a liquid form of the cryogen having a high cooling potential is situated below the liquid-vapor interface 20. An outlet conduit 22 for delivering the gaseous and liquid forms of the cryogen from the pressure vessel 10 is provided with a movable section 26 that is actuated to move above and below the liquid-vapor interface 20 to deliver respectively the cryogen in its gaseous or liquid phases and/or is oscillated above and below the liquid-vapor interface 20 to deliver the cryogen as a two phase flow. A timing control circuit is provided to selectively regulate the time intervals that the movable section 26 is above and below the liquid-vapor interface 20 to meter the amounts of the gaseous and liquid forms of the cryogen that are delivered and/or the time intervals that the movable section 26 is above and below the liquid-vapor interface during each period of oscillation to regulate the cooling potential contained within the two phase flow.