Dwyer Instruments A-331 Filter Vent Plug 1/8" NPT

The Dwyer Instruments A-331 Filter Vent Plug is a pressure equalization and venting element that is installed in HVAC systems to eliminate stagnant air in the liquid or gas lines. Its main purpose is to permit the escape of air and avoid the loss of fluid by a spring-loaded venting system that open when the pressure rises to a set limit. It requires running the plug into a 1/8" NPT opening of filters, separators or valves. It also ensures proper pressure readings in chillers, hydronic loops, and air handlers and decreases air binding, enhancing the overall flow stability.