Patent attributes
A system includes a first valve fluidly connected to a first vessel and a second valve fluidly connected to a second vessel. The first valve includes a body and a piston. The body includes first and second ports and a bore having a longitudinal axis. The first port is in communication with the bore and an interior of the first vessel. The second port is in communication with the bore, the second valve, and an atmosphere exterior to the first vessel. The piston is movable along the longitudinal axis of the bore. A first position of the piston blocks the first port; a second position of the piston allows fluid communication between the first and second ports. The first valve is configured so that fluid pressure from the second valve, communicating through the second port, urges the piston to the second position.
