Block & Bleed Valves

Block and Bleed
A Block and bleed manifold is a hydraulic manifold that combines one or more block/isolate valves, usually ball valves, and one or more bleed/vent valves, usually ball or needle valves, into one component for interface with other components (pressure measurement transmitters, gauges, switches, etc.)
Double Block and Bleed
The primary function of a double block and bleed system is for isolation and the secondary function is for intervention.
Under certain conditions double block and bleed systems are needed to prevent product contamination or where it is necessary to remove essential equipment from service for cleaning or repairs while the unit continues in operation.
Of course, such equipment must be provided with a spare or it must be possible to bypass it temporarily without shutting down the unit.
The nature of the fluid, its pressure and temperature, and many other factors must be considered when determining the need for double block and bleed systems.