Pressurized barrier fluid circulation by external system .
Isolate process fluid
Zero process emissions .
Seal cannot induce circulation
Used with pressurized dual seals .
High vapor pressure fluids ,light hydrocarbons
Heat transfer fluids
Dirty /abrasiveor polymerizing fluids
Piping loop must be fully vented before starting
Circulating system must be pressurized and energized at all
times .Barrier fluid must be compatible with process .
Circulating system level indicator shows both inboard and
outboard seal leakage .