A safety switch operating mechanism having an engagement mechanism mechanically linked to a plunger and arranged to receive an actuator such that insertion of the actuator into the engagement mechanism moves the plunger to a first position and removal of the actuator from the engagement mechanism moves the plunger to a second position. A rack and pinion housing is operatively connected to the pump via a conduit line. In some embodiments, the fire barrier may include a plurality of intumescent sections and a plurality of foam sections with each foam section being positioned between at least two of the intumescent sections. Before the clutch is brought into the engagement state, a pulsed drive current D is supplied to the solenoid valve.