Abstract: An apparatus for pneumatically actuating slave devices in direct response to the discharge of a dry chemical fire extinguishant is disclosed comprising at least one main fire extinguisher from which pressurized dry chemical fire extinguishant passes into a main discharge pipe, and a cartridge containing a pressurized gas connected to the main discharge pipe through an actuator valve. The actuator valve includes a resilient check closing the valve due to the pressurized gas in the cartridge and a piston having a head fit into the actuator valve at sufficiently close tolerance to minimize gas transfer therethrough. The piston head is disposed toward the main discharge pipe and an integrally connected base portion faces the tip of the check and is disposed such that depression of the piston head into the actuator valve moves the check, opening the valve and releasing the contents of the cartridge into a secondary discharge pipe.