The Type 543 3-way Ball Valve shall be available in horizontal and vertical body types.  The ball shall be fully molded and full port.  The L-port ball shall have blocking capability when in the OFF position.  The stem shall be blowout proof, utilizing a double o-ring seal and a predetermined break point opposite the media side of the stem seals.  The seat carrier shall be adjustable and reverse threaded.  The handle shall double as a seat carrier adjustment or removal tool.  Horizontal versions shall utilize a true union connection with a seat carrier on all three ports. Vertical versions shall utilize a true union connection and seat on the two main ports only.  The branch connection on vertical versions shall be metric spigot and a metric-ASTM coupling shall be provided.  The valve nut threads shall be of buttress type.  Ball seats shall have an elastomeric backing o-ring and all elastomeric seals shall be of like material.  All valves shall be tested in accordance with ISO9393 and designed to ISO16135 standards.  All valves shall be manufactured under ISO9001 for Quality and ISO14001 for Environmental Management. Following assembly, every valve shall be certified bubble tight.