Filler apparatus for providing cryogenic liquid coolant to dewars such

Abstract

A filler apparatus for cryogenic dewars, such as are used in infrared detectors in infrared spectrometers, has an inlet port funnel which is connected to a liquid delivery tube which extends downwardly and into the liquid coolant containment vessel of the detector. A gas discharge tube extends co-axially with and spaced outwardly from the delivery tube and is connected to the fill port of the detector to direct gas resulting from evaporation of coolant within the detector up to a gas outlet funnel which is itself co-axial with and spaced outwardly from the inlet port funnel. A screen is mounted over the tops of the inlet and outlet funnels. The coolant, such as liquid nitrogen, is poured by the operator into the inlet funnel, which may be located at a position on the top surface of the cabinet of the spectrometer, and the operator can observe whether the detector is overfilled by noting whether the coolant liquid overflows into the gas discharge tube or up into the space between the inlet and outlet funnels. Because gas resulting from evaporation is directed upwardly and discharged through a space which is separated from the liquid delivery tube, backflowing of the liquid coolant in the delivery tube and funnel is minimized. By allowing the operator to introduce the liquid coolant to an inlet port at the top of the spectrometer cabinet, filling of the detector is simplified.