Low diffusivity barrier fluid packing system

摘要

In accordance with the present invention, there is provided a fluid or liquid barrier packing system which is adapted to minimize VOC emissions, while also providing live-loading and continuous load monitoring functions. The components of the packing system (including the liquid barrier) are adapted to be installed in a traditional stuffing box of a valve utilizing a top entry method, and without the necessity of having to inject the liquid through any side ports of the valve. The packing system reduces leakage levels as required by low emission leakage specifications by creating a reverse osmosis effect, limiting the diffusivity of a gas through the packing elements of the system. Thus, the packing system of the present invention provides a simplified method to load and monitor a barrier in the stuffing box of the valve to slightly higher pressure than processed fluid pressure.

主权项

1. A valve adapted to satisfy low fugitive emission leakage standards, the valve comprising:
a valve body defining a central passageway; a valve stem advanced through and reciprocally movable within the passageway; a packing system at least partially disposed within the passageway and including:
an annular upper packing which circumvents the valve stem and is disposed in fluid tight engagement to the valve stem and the valve body;an annular lower packing which circumvents the valve stem and is disposed in fluid tight engagement to the valve stem and the valve body, the upper packing being separated from the lower packing by an annular gap which is further bounded by portions of the valve body and the valve stem;a fluid barrier filled into the gap, the upper and lower packings and the fluid barrier collectively defining a seal of the packing system; anda live-loading sub-assembly cooperatively engaged to the seal and operative to apply a load thereto in a manner which maintains the fluid barrier thereof at a prescribed fluid pressure level; and an annular load sensor having a body which circumvents the valve stem and is positioned adjacent the upper packing.