A valve assembly is provided, the valve assembly comprising a body that defines a fluid flow path between an inlet and an outlet with a frangible member between the inlet and the outlet across the fluid flow path so as to block fluid flow The valve assembly also includes a member for rupturing the frangible member, a spring biasing the rupturing member into contact with the frangible member and a member for retaining the rupturing member away from the frangible member. A magnet is spaced apart from the retaining member, and a non-magnetic sleeve is disposed between the magnet and the retaining member. The non-magnetic sleeve blocks a magnetic field provided by the magnet. Also included is a trigger for removing the non-magnetic sleeve, wherein, when the non-magnetic sleeve is removed, in use, the magnetic field attracts the retaining member to release the rupturing member to cause rupture of the frangible member.