The Double Block & Bleed (DB&B) plug valve is a valve concept, which was designed in the early nineties. The design makes use of the already proven design from the Super-H plug valve: same stem construction, same equalizer ring, same plug, same... The only thing which is different is, that instead of one plug in one body the DB&B valve has 2 plugs in one body.
When a DB&B function was needed before this type of valve was designed, it was necessary to have two individual valves with a spool piece and a bleed function between the valves. With the DB&B plug valve you get two individual closing members (true double block and bleed) in one body.
The compact design gives space and weight reduction, which in many places is highly appreciated. From pressure class 600# and upwards, the face-to-face dimension is the same as single valve. Pressure class 150# and 300# have the same face-to-face dimension as pressure class 600#.
The DB&B valve has the same leakage rate as Super-H (bubble tight), but the DB&B design lets you verify it via the bleed.
As a standard on all the DB&B valves Serck Audco delivers the valves with the unique and patented Protected Pressure Balancing system.