Basic requirements for centrifugal pump technology

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Centrifugal pumps shall meet the requirements of this standard and be manufactured in accordance with the product drawings and technical documents approved through prescribed procedures. Centrifugal pumps shall be able to operate continuously and normally under the following operating conditions (or water quality specified in GB 5084): a) the temperature of the medium does not exceed 80°C; b) the pH value of the medium is between 6.5 and 8.5; c) the volume fraction of solid impurities in the medium does not exceed a certain limit. .1%, with a particle size not exceeding. 2 mm. The manufacturer should provide the performance curve for each pump (curves showing the relationship between head, efficiency, shaft power, and NPSH versus flow rate). The recommended operating range for the pump is as follows. .7Q。 1. 2Q, (Q is the flow rate at the specified point). Performance and its tolerances: The performance deviation of the pump shall comply with the requirements of Grade 2 specified in GB/T 3216-2005. The vibration intensity of the pump shall meet the requirements of Class C as specified in JB/T 8097-1999. The noise level of the pump shall meet the requirements of Class C as specified in JB/T 8098-1999. The required net positive suction head of the pump must not be lower than the specified value. The deviation shall comply with the provisions of GB/T 13006. Structure: The nominal pressure of the inlet and outlet flanges of the centrifugal pump is 0.6 MPa when the specified head of the pump is less than or equal to 50 m; it is 1.6 MPa when the specified head is greater than 50 m. The flange connections shall comply with the requirements of GB/T 17241.6. The pump body should be equipped with a drain hole, an exhaust hole, and pressure measurement holes on the inlet and outlet flanges. The locations of the drain hole and the exhaust hole should facilitate the removal of liquid from within the pump as well as any accumulated air. The pump body should also be equipped with a water inlet hole or cup; the water inlet hole can be used as an exhaust hole as well. A water seal should be installed on the pump shaft to prevent water from entering the bearings. When using soft packing, a shaft sleeve should be installed; it must be securely fixed to the shaft and rotate together with it. For pumps used at reduced speeds, when the head is below 12.5 m, it is not necessary to provide a balance hole or a rear sealing ring. Depending on the different operating environments and the requirements for power systems, the structural design of the pump can vary, but its specified performance, efficiency, and net positive suction head must comply with the provisions of this standard. For the sealing of centrifugal pumps, the shaft seal can be a mechanical seal, a rubber-sealed shaft seal, or a soft packing seal. The dimensions of the shaft seal cavity shall comply with the requirements specified in GB/T 5661. When using soft packing seals or skeleton rubber oil seals, a shaft sleeve should be installed on the shaft, and the surface of this sleeve must be free from defects such as scratches or rust spots. Bearings and lubrication: Deep groove ball bearings shall comply with the provisions of GB/T 276; other bearings shall comply with the provisions of the corresponding standards. The operating temperature of the bearing shall not exceed 40°C relative to the ambient temperature, and the maximum working temperature shall not exceed 80°C. Bearings can be lubricated with grease or light oil. Coupling or pulley: The centrifugal pump is driven by a prime mover through an elastic coupling or pulley, and the installation accuracy of the elastic coupling must meet the requirements specified by the manufacturer or relevant standards. The two halves of the coupling or the pulleys must be securely fixed to the shaft, with no axial or circumferential movement relative to the shaft allowed. When the pump is driven directly by a motor via a coupling or by a prime mover through pulleys, protective covers should be provided. The base of the centrifugal pump, as well as its installation dimensions, shall comply with GB/T 566. The regulations state that when the pump and the power unit are connected by a belt drive, no base is required. Regarding the material requirements for the main components of the pump, cast iron parts must comply with the specifications outlined in JB/T 6880.1–6880.3. High-quality carbon structural steel shall comply with the provisions in GB/T 6”. Stainless steel parts shall comply with the provisions in GB/T 1220. Alloy steel parts shall comply with the provisions of GB/T 3077. Rotating components such as impellers, couplings, and pulleys must be balanced. Components in the pump that are subjected to working pressure should undergo water (or air) pressure tests; there should be no leakage or seepage. The test pressure should be 1.5 times the working pressure (but not less than that value). .2 MYa), lasting 5 minutes. Assembly and appearance requirements: All components must pass inspection before assembly can proceed (subcontracted parts, purchased parts, standard parts, etc. must come with quality certificates). For the assembled pump, the rotating parts should move smoothly and freely, without any signs of rubbing or sticking. The exposed machined surfaces should be protected against rust. All fasteners must not be loose. The outer surface of the pump should be free from any dirt, damage, or rust. The painting of the pump shall comply with the provisions of JB/T 5673. The pump shall have a distinct red indicator for the direction of rotation, and this indicator must remain legible throughout its service life. The pump’s inlet and outlet should be sealed to prevent debris from entering the pump. Safety: The safety requirements for the pump must comply with the provisions of GB 10395.8. The safety markings of the pump shall comply with the provisions of GB 10396. Reliability: Under specified operating conditions, the average operating time before the first failure of the centrifugal pump should be no less than 5,000 hours. During reliability tests, apart from performing maintenance as specified by the manufacturer and replacing wear-prone components at designated intervals, no other parts shall be replaced