Ball valve classification 1) Commonly used ball valve according to their working principle is divided into floating ball valve, fixed ball valve, lifting rod valve. 2) The ball valve can be divided into straight-through type, three-way type and right-angle type according to its channel position. The latter two ball valves are used to distribute the medium and change the flow of the medium. Ball valve construction, installation points 1) installation location, height, direction of import and export must meet the design requirements, the connection should be strong and tight. 2) All kinds of manual valves and handles installed on the pipe should not be downward. 3) The valve must be installed before the appearance inspection, the valve nameplate should be consistent with the current national standard "General Valve Flags" GB 12220 requirements. For the working pressure is greater than 1.0 MPa and the main pipe to play the role of cut-off valve, the installation should be carried out before the intensity and tightness test, qualified after the standard use. Strength test, the test pressure of 1.5 times the nominal pressure, the duration of not less than 5min, valve housing, packing should be no leakage as qualified. Tightness test, the test pressure is 1.1 times the nominal pressure; test pressure in the test duration should be consistent with GB 50243 standard requirements, no leakage valve plate sealing as qualified. 4) valve flange and pipeline flange according to the pipeline design requirements installed gaskets. 5) ball valve with transmission, according to the instructions of the product installation instructions. Ball valve implementation of the standard product standard "Universal valve flange and butt welded steel ball valve" GB / T12237-89 "Iron and brass ball valve" GB / T "General requirements for steel valves" GB / T 12224- 2005 "drinking water distribution equipment and protective materials safety evaluation criteria" GB / T