Following the product families of the compact flame monitors D-LX 200 and D-LX 100, TÜV Süd Industrie Service have now also confirmed that the separate design DURAG flame monitors fulfil the requirements for permanent operation up to SIL3. With the product families D-LE 103, D-LE 603, D-GT 800, D-UG 120, and D-UG 660 now all DURAG GmbH flame monitors for permanent operation are confirmed with SIL3. Also for the separate design devices (flame sensor and control unit) this high SIL level was achieved with a proof test interval of 15 years. An important basis for the good rating is the two channel design of the DURAG control units which is already used for more than 20 years. The two channel architecture of the devices ideally unifies high safety together with high availability.