Abstract: A safety device for a tube (8) for inserting or removing a liquid substance for storage in a storage facility in a cavity in a water-impregnated rock mass, said liquid being the liquid phase of a substance which is a gas at ordinary temperature, which liquefies under pressure, which has a density which is less than the density of water and which is immiscible with water, said liquefied gas being stored in said cavity under the liquid-gas equilibrium pressure applicable to the ambient temperature in the cavity, the safety device being constituted by a can (9) which is open at the top and which is disposed around the bottom end (81) of the tube to which it is applicable such that the bottom opening of the tube (8) is located near to the bottom of the can, the volume of the can being greater than the volume of the tube up to a height corresponding to the head of water necessary for reaching an equilibrium pressure with the cavity.

Abstract: A draining well (2) extending downwardly from the bottom (3) of an underground cavity for storing liquefied gas under pressure has an upper portion (9) of large area and a lower portion (10) of smaller area. The volume of the upper portion is sufficient for filling a service tube (5) with water up to its hydrostatic equilibrium level. This enables the depth of the draining well to be reduced and thus makes such a storage facility cheaper to produce.

Abstract: A liquefied gas such as propane is stored in underground galleries wherein there is a gaseous phase above a liquid phase and at the bottom, water in a sunk draining trap. The storage is worked, i.e., gas is introduced or extracted through tubes extending into the lower part of the liquefied gas. In case of emergency, failure or damage to the implements, the stored product is isolated. The water level is raised for covering the lower end of the tubes and water is allowed to rise up in the tubes until the pressures are in balance.