Safety device for a filling tube of an underground facility for storing liquefied gas under pressure

A safety installation for a vertically oriented tube (8) for inserting a liquid substance for storage in an underground cavity (1) defined in a water-impregnated rock mass, said liquid being a liquid phase of a substance which is a gas at ordinary temperature, which liquefies under pressure, which has a density less than the density of water, and which is immiscible with water, said liquefied gas being stored in said cavity under a liquid-gas equilibrium pressure applicable to the ambient temperature in the cavity, said safety installation being characterized by:

• a bottom, open outlet end (81) of the tube being disposed in an upper, gaseous phase portion of the cavity, and above a level (10) of the liquid stored in the cavity, and a can (9) open at a top thereof and disposed around the bottom end of the tube such that said bottom end is disposed proximate a bottom of the can, the volume of the can above said bottom end of the tube being greater than the volume of the tube up to a height corresponding to a head of water necessary for reaching an equilibrium pressure with the cavity.