In case the DBB-SAVER is used on a system containing gas, the isolation configuration can be a classical Double Block & Bleed (DB&B – existing of 2 in line valves and a smaller bleed valve) or Single Valve (SV).
With most common valve types used in the industry (e.g. a ball valve, gate valve, plug valve, etc.) the valve contains two seats. These can be active seats, mimicking a classical DB&B configuration, or passive (self relieving) seats, usually designed to make bi-directional flow possible.
DB&B provides a higher degree of safety compared to any SV configuration.
And a SV with double active seats provides a higher degree of safety compared to passive seats.
When connecting the DBB-SAVER to the bleed or drain connection of a SV body cavity, the safety level that a SV can provide is increased significantly.
Safe working behind leaking valves becomes possible when deploying a DBB-SAVER. Even if the isolation is provided by only a single valve.