What is the difference between an SDV valve and a BV valve?

The BV (block valve) valves of our company (Shafer+Carmeron) are mainly used in main pipelines, such as in main pipeline valve chambers, to provide protection in the event of a pipe rupture. On the other hand, the SDV (shutdown valve) valves (Bettis+Carmeron) are primarily used at the entrances and exits of stations, serving to allow gas flow under certain conditions while enabling rapid shutdown; BV valves can also be used as SDV valves in stations. It’s not possible to reset these valves on-site; electronic resetting must be done through the station control system. I’d really like to see actual photos from your end. According to the locking principle of BV valves, it is the 3-way valve with a normal closed position identified as number 23 that is activated by high-pressure gas after pressure reduction; therefore, to reset it, the flow needs to be interrupted in the upward direction. As for the SDV valves, I’m not familiar with their working principle there, so it would be best if you could send some photos along with information about their actuators – it’s possible that they use the same type of mechanism.

As a supplementary note, the pilot valve with number 23 is a pneumatically locked valve.