Multi-operational valve

A valve for selectively fluidly communicating a first fluid volume and a second fluid volume, the valve comprising:

• a valve body;
• an inlet orifice in fluid communication with the first fluid volume;
• an outlet aperture in fluid communication with the second fluid volume and in selective fluid communication with the inlet orifice by a first fluid flow path;
• an activation member axially movable relative to the valve body;
• and
• a plunger axially movable within the valve body, the plunger including an aperture therethrough defining a second fluid flow path between the first and second fluid volumes;
• wherein the valve is operable in a first mode in which fluid flow is only permitted along the first fluid flow path in response to manual actuation of the activation member, and
• wherein the valve is operable in a second mode in which fluid flow is only permitted along the second fluid flow path when a pressure difference between the first and second fluid volumes reaches a predetermined value.