Lung demand regulator

A valve assembly for a lung demand regulator of a breathing apparatus comprising:

• a regulator valve apparatus for regulating a flow of breathing gas, the regulator valve apparatus being actuatable between a closed position in which no flow is permitted and an open position in which flow is permitted;
• a lockout mechanism configurable in:
• i) a lockout configuration in which the regulator valve apparatus is secured in the closed position, and ii) a release configuration in which the regulator valve apparatus is freely moveable;
• wherein the lockout mechanism comprises an axially compressible spring element;
• wherein the spring element is configured to be laterally deflected in a first direction in the lockout configuration and laterally deflected in a second direction different from the first direction in the release configuration;
• and
• wherein lockout mechanism is configured such that the spring element is axially compressed during movement of the lockout mechanism between the release configuration and the lockout configuration.