By contrast, gate valves are bidirectional, and may fully shut from the circulation of fluid, vapour or gas in equally Instructions when within a shut posture. Disc: The disc (Determine 2 labeled C) sits on the nozzle and moves up and down to allow or reduce circulation from the safety https://josuedpolv.bloggip.com/28403606/considerations-to-know-about-brass-safety-valve