Page 266 - Water Standards
P. 266

Table 4   2   12-1 (Continue)

             No           Item               Allowable error  Explanation
                                         Meet requirements of Item 10
                    Valve  casing  composite
             2                         of Article 4   2   2 in this specifi⁃  —
                 joints
                                       cation
                                         No leakage under 0   05MPa pre⁃
             3     Rubber seal air tests                         —
                                       ssurised air
                             Aerated water
                                         No gap                  —
                   Gap when    seals
             4     the valves
                   are closed  Un⁃aerated
                                         ±20% of the design value  —
                             water seals
                                         The water leakage shall be no
             5     Tightness tests in still water  larger than the design value  —
                                       when holding 30min

               2  Ball valve installation shall meet the following requirements:
                 1) Allowable installation error of the ball valves shall meet the requirements of Table
                   4   2   12-2.
                 2) Ball valves shall be able to move freely. Enough gap shall be left between the ball
                   valves and fixed parts. The gap should not be less than 2mm  
                  Table 4   2   12-2  Allowable installation error of ball valves
             No          Item              Allowable error   Explanation

                    Composite joint between    Meet relevant requirements of
             1                                                  —
                 valve seat and base plate  Item 10 of Article 4   2   2
             2     Valve body center    ±5mm                    —
                    Valve  body  transversal
             3                          15mm                    —
                 center








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