The systems of the GAOS S-SV series have more capabilities than those of the GAOS S-SD series in terms of autonomous use. As a rule, all models of this series have a digital indication system, a keyboard for adjustment, actuating relays, and sound alarm systems. Group of systems GAOS S-SV-5021-SM Auxiliary equipment of this group is made in the form of two blocks: MKT-1m module with ISM installed in it; module of switching, indication, control and interfacing of MKIUS. All systems of the GAOS S-SV-5021-SM series have an interface “current loop 4-20 mA”. Type of explosion protection – “flameproof enclosure”. The systems of the GAOS S-SV-5021 series are divided into two main groups: relay systems and network systems. Network systems (versions 5021-03 and -13) support the RS-48S digital interface but do not have actuating relays. Relay systems (5021, 5021-02, -10 and -12), on the contrary, are equipped with actuating relays, the connector for connection to the RS-48S channel is not provided. The MKT-1m module can either be directly screwed into the MKIUS unit or connected to it with a 1.8 m cable (can be changed upon special order). Versions without indication and the keyboard are also possible (for example, for a decrease in energy consumption). Gas analysis systems GAOS S-SV-5022-SM and GAOS S-SV-5023-SM are made in plastic and metal housings, respectively. Both systems have intrinsic safety type 1a explosion protection, a digital indicator and keyboard, three executive relays and a built-in sound alarm, as well as the Current loop 4-20 mA interface.