Abstract: A nostril blocker adapted for retained mounting upon the mouthpiece of breathing equipment and comprising a bifurcated resilient element that in use is disposed generally parallel with the mouthpiece gas passage and spaced therefrom by a distance such as to position limbs of the element to straddle the nasal septum and obturate the nostril openings of the user.

Abstract: Emergency breathing equipment intended to provide short term life support by ducting breathable gas from a small capacity source to a user via a restricted flow path that allows only limited flow rates so as to prevent hyperventilation and wastage of breathable gas is characterised by a demand valve having the poppet controlled by a demand pressure-sensing diaphragm to control an inhalation flow path, the diaphragm also controlling an exhalation flow path so as to switch the user between said flow paths by opening one and closing the other, as it moves between two positions under the influence of demand pressure. The equipment is also characterised by a reactive pressure regulator for the breathable gas and having its delivery pressure switchable by a trigger element that in an installed position unloads the reaction member so as to provide zero delivery pressure, withdrawal of the trigger element allowing the reaction load to operate to set a fixed positive delivery pressure.

Abstract: A fluid control valve having a discharge port controlled by an obturator is characterised by the discharge port being shaped to cause a marked drop in back pressure at a small critical opening distance of the obturator from the port, thereby to provide impetus to initiating discharge. The discharge port has effectively a concave surrounding surface for this purpose. To achieve good sealing with light loading, the port preferably also has a convex surface immediately surrounding its orifice. The preferred configuration is a convex surface bounded by a wall. The obturator may be resiliently loaded to enable its response to dynamic effects of fluid flow to enhance opening "lift". The obturator may be, e.g. a lever, a diaphragm or the armature of a solenoid.