Description
Flow is normally allowed from 4 to 3. When pilot pressure at 1 rises above the combined pressure of the spring bias, plus pressure at 4, the valve shifts to block flow between 3 and 4, while diverting flow from 1 to 2. A constant pressure drop is maintained across a fixed (or variable) orifice upstream of 4 when installed and piloted per the diagram above. In this case, flow priority is given to 3, with flow in excess of the orifice differential requirement being by-passed to 2.