To be fully secure against fire, flame detector self-testing is not enough. According to most local jurisdictional authorities and as required for SIL2 compliance, you need to test and ensure the integrity of your entire flame detection system at least once per year. That means performing a full system loop test from the detector, through the wiring to the controller, and up to the actual alarm notification. The only way to do so, without lighting a real fire, is with an external flame simulator.