Ordinary Hazard may cover the simulator, but it sounds like it is expensive enough that they won't want it to get wet. CeaseFire makes a Class ABC automatic extinguishing system (dry chemical). Also, a Fike FM200 clean agent may be an appropriate system. You may be able to get away with placing a fire extinguisher in the flight simulator. That would be covered under equivalency 1.5.2 and must be approved by the AHJ. That might be my first approach.