| 摘要 |
Liquid nitrogen contained in an insulated vessel (12) is dispensed in gaseous and/or liquid form via an outlet pipe (50, 51). A sample of gas is taken from the headspace (30) and pumped through a closed loop (32) outside the container. The sample takes up heat in the loop and is re-introduced via an inlet (36) so as to impinge on the liquid surface (28), thus heating a surface layer and increasing the pressure in the container whereby fluid can be dispensed. In a modification the warmed gas sample is bubbled through the liquid pool (26) so as to heat a localised column of liquid. The invention is applicable to the controlled dispensing of fluids stored cryogenically. <IMAGE> |
