4.4 The motor rated power should be at least equal to K times the maximum shaft power of the metering pump (including the power loss of the gear box, coupling). K value is selected according to the following table. Maximum shaft power Pa (kW) Maximum shaft power Pa (kW) K Pa ≤ 3150% Pa ≤ 19125% 19Pa> 55110% 4.5 Effective NPSHa NPSHr and necessary NPSHr should be based on the same reference plane. When the difference between NPSHa and NPSHr is less than or equal to 0.6m, the NPSH should be carried out. 5. Structural Design 5.1 Pressure-Bearing Parts 5.1.1 The maximum permissible outlet pressure of the pump shall be at least equal to 110% of the rated outlet pressure of the pump. 5.1.2 All pressure parts (including the impact of the import pressure area) should be designed to allow the maximum outlet pressure pumping temperature, the allowable stress of the material taken: for domestic pump, should not be greater than HG20531-93 (cast iron, steel Container) maximum allowable stress value; Imported pumps, should not exceed ASMESectionVIII provisions of the maximum allowable stress value. 5.2 Interfaces 5.2.1 All interfaces are flanged unless otherwise specified on the data sheet. 5.2.2 Unless otherwise specified, domestic pump inlet and outlet connecting flange shall comply with the provisions of GB9112, import pump inlet and outlet connecting flange shall comply with the provisions of ANSIB16.1 and 16.5. Flanges with a diameter or thickness greater than the above are also permissible. 5.2.3 Import and export flanges should be taken at the same level of pressure flange. 5.3 Plunger Pumps 5.3.1 The stuffing box shall be fitted with a packing ring for flushing or lubricating the packing. 5.3.2 should ensure that the liquid end packing seal leakage liquid does not enter the power side. 5.4 diaphragm pump 5.4.1 single diaphragm pump diaphragm or double diaphragm pump first diaphragm should be limited agencies. 5.4.2 Double Diaphragm The two diaphragms of the pump should be filled with inert liquid (and the process medium on both sides of the diaphragm, the hydraulic oil should not be mixed), and a probe should be provided to alert the diaphragm when the diaphragm ruptures. 5.5 Bearing Bearings should be the standard form, shall not be made by the manufacturer's own non-standard bearings. 5.6 Buffers If specified on the datasheet, the import and export bouncers shall be provided by the seller and shall be of the type negotiated jointly by the buyer and the seller. 5.7 safety valve 5.7.1 diaphragm pump oil chamber safety valve should be able to automatically reset and adjust, repair, easy to replace, the set pressure should be at least 110% of the rated pressure of the metering pump. 5.7.2 If specified in the data sheet, the external relief valve for the plunger pump shall be provided by the seller. 5.8 Auxiliary piping 5.8.1 If piping systems such as lubrication, cooling and seal flushing are required, the seller shall provide and install it on the pump and / or base. 5.8.2 The plumbing, fittings, etc. of all piping systems shall be not less than 1/2 in. (13 mm) thick and shall not have a wall thickness of less than 1.6 mm (1/16 in.). 5.8.3 Pipe fittings of 1-1 / 4 (32mm), 3-1/2 (90mm), 7 (175mm), 9 (225mm) inches shall not be used unless otherwise specified.