Improvements in or relating to valve systems

... 834,799. Ventilators. MINISTER OF WORKS. June 6, 1955 [March 5, 1954], No. 6584/54. Class 137 [Also in Group XXIX] A chamber is isolated from the effects of extraneous impulsive waves occurring in an atmosphere 2 with which the chamber normally communicates through a duct 1, by a labyrinth 3a, 3b, 3c arranged to form part of the duct and through a valve 13, 16 associated with the duct 1, arranged so as to be directly responsive to pressure waves occurring in the atmosphere 2, the valve being operative to effect closure of the duct between the labyrinth and the chamber before the pressure wave can affect conditions within the chamber. Normally air passes through non-coincident holes 16a and 13a in a movable and fixed valve plates 16, 13 respectively, these holes being closed when sudden pressure at 8 forces a cap 9 to slide down on 3b and move valve plate 16 against a spring 17. An additional valve plate may be arranged to close on suction Fig. 3 (not shown). The labyrinth may serve a plurality ...