Hansen H8021, H8022, H8024, H8025 Three Way Dual Safety Relief Valve Manifold   These rugged, forged steel bodied valves facilitate the
parallel installation of pressure relief valves. Because
three-way valves will not isolate both pressure relief valves
simultaneously, they are considered the only acceptable
type of shut-off valve for use with refrigerant relief piping.
Their durable metal-to-metal seating and patented nonleak
packing plus o-ring stem seal design combine for
long, trouble-free service. Inlet and outlet connections
are threaded female NPT all the same size.
Shown below is a three-way dual shut-off valve in the
stem out position (backseated). The valve stem should
be positioned so that only one pressure relief valve is
activated. While the valve can be either frontseated (front
port is closed) or backseated (back port is closed), the
backseated position (shown) is recommended for normal
use because it takes pressure off the packing and reduces
the possibility of packing leaks.