PURPOSE: To stabilize a boiling point of a freezing mixture irrespective of a change in altitude by providing a burst valve which operates to release the internal pressure of a heat insulated vessel and an emission pipe when the pressure becomes high extraordinarily and a control device for maintaining the boiling point of the freezing mixture in the heat insulated vessel at a prescribed value.

CONSTITUTION: An evaporative emission passes through an emission pipe 14 and a burst valve 15 and is discharged outside an airframe from a first port 17 for discharge outside the airframe, while the pressure is controlled by a control device 16. The burst valve 15, which leads the evaporative emission to the control device 16 from the emission pipe 14 at a normal time, operates to lead the evaporative emission to a second port 18 for discharge outside the airframe and to discharge it outside the airframe so as to avoid danger, when the pressure of the evaporative emission becomes high extraordinarily. Accordingly, it is possible to stabilize a boiling point of a freezing mixture irrespective of a change in altitude and to execute an operation of injection of the freezing mixture in a condition that it is mounted on an aircraft.