Abstract: A safety valve meant to be fitted on an impervious wall separating two separate spaces.According to the invention, the valve comprises on the one hand, a first stationary and relatively rigid part, which is meant to be fixed on the wall and comprises a first cylindrical sleeve and on the other hand, a second part at least partly flexible and resilient, adapted to be connected with the first fixed part and comprising a second cylindrical sleeve, co-axial to the first and coming into sealing contact thereon or moving away therefrom depending on the resilient deformations to which the second part is at least partly subjected because of the pressure differences existing on either sides of the wall.