Beginner's question -- What is a DBB valve seat?
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I saw someone asking whether there are DBB valve seats for floating ball valves? What is a DBB valve seat?
A double block-and-bleed valve (DBB) is a valve that features two sealing pairs; in its closed position, both sealing pairs can maintain a sealed state simultaneously. The valve body within the intermediate chamber (between the two sealing pairs) has a port for releasing the pressure of the medium. The symbol DBB... represents Baidu. . .
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Double-block and bleed valve: A single-unit (non-combined) valve with two valve seat sealing surfaces that, when in the closed position, can block the medium pressure coming from both the upstream and downstream sides of the valve; there is also a discharge path for the medium contained within the valve body cavity between the valve seat sealing surfaces. When this type of valve is subjected only to the pressure of the medium from a single direction (upstream or downstream), it does not provide true double isolation.
The floating ball valve features forced sealing at the outlet end and does not have a DBB seat.