A Block and bleed manifold is a hydraulic manifold that mixes a number of block/isolate valves, typically ball valves, and a number of bleed/vent valves, generally ball or needle valves, into a single element for interface with other factors (pressure measurement transmitters, gauges, switches, etcetera.) of a hydraulic (fluid) program. http://josuehhgdy.blogs-service.com/17948983/manifold-valve-an-overview