Seeking knowledge about centrifugal pumps

(1) The maximum number of stages for impellers in multi-stage pumps and high-pressure hydraulic turbines is 11; (2) For impellers made of 12% Cr material, the maximum tip speed shall not exceed 80 m/s； (3) Induction wheels should not be used with horizontal pumps ； (4) The MAWP shall not be less than 110% of the shut-off pressure when operating with the rated impeller at the MAWT. The pump area subjected to inlet pressure shall be designed in accordance with MAWP ； (5) The pump must have a stable head/flow curve that rises continuously up to the shut-off point. The increase in head should preferably be 10–15% of the head at rated flow, with the maximum increase not exceeding 20% of the head at rated flow ； (6) The optimal efficiency point should preferably be located between the normal flow rate and the rated flow rate ； (7) In the range from the minimum stable flow rate to the rated flow rate, the NPSH margin should be at least 1 m or 15% of the effective NPSH, whichever is greater ； (8) The cavitation specific speed shall not be higher than 13000 (m³/h, m) ； (9) The margin between the design temperature for continuous pump operation and the specified operating temperature shall be not less than 28°C. (10) Each impeller shall be individually protected to prevent its axial movement ； (11) At any location 1 meter away from the pump set, the noise level is expected to be no more than 85 dBA ； (12) When selecting segmented multi-stage pumps for high-temperature (above 250°C) or low-specific-density media, due attention should be paid to the manufacturer’s experience and performance records ； (14) The single-stage head of centrifugal pumps is generally between 20 and 200 meters; for higher heads, two-stage or multi-stage pumps are usually chosen ； (17) The rated impeller diameter of the pump should not be the maximum impeller diameter permitted for that pump; there should be at least a 5% head margin ； (18) For media with a viscosity > 20 mm2/s or containing inorganic particles, it is necessary to convert to the rated flow rate and head when transporting clean water ； (19) The rated flow rate is generally taken as the maximum flow rate; if this value is not available, 1.1 to 1.15 times the normal flow rate is usually used ； (20) Pumps (including auxiliary equipment) shall be designed and manufactured for a service life of at least 20 years (excluding wear parts), and shall be capable of operating continuously for at least 3 years. (21) The torsional natural frequency of the entire pump set shall be at least 10% higher or 10% lower than any possible excitation frequency within the specified speed range.