Multistage centrifugal pumps are widely used in industry, agriculture, municipal engineering and other fields. A drop in operating pressure will directly undermine the efficiency and safety of the entire system. Combining years of technical practices, Lishengde Energy-saving Pump Industry analyzes the core causes of pressure reduction as follows:
The pump model shall be selected to match the flow demand of the system. The structure of impellers, including blade angles and stage configuration, directly determines the head performance. Deviated flow parameters in design or excessive hydraulic loss of impellers will result in insufficient pressure output. During manufacturing, inadequate material strength or machining errors (such as excessive impeller clearance) will also lead to pressure decline.
An increase in medium viscosity raises the effective head loss when fluid passes through the impeller, thus reducing the pump discharge pressure. Abnormal fluid density (e.g. gas entrainment or foreign impurities) will disrupt the stability of the internal flow field. In particular, media containing solid particles will cause impeller wear and further lower the pump pressure.
Insufficient motor speed (caused by belt slippage or incorrect inverter parameters) or excessive pipeline flow (beyond the designed maximum flow of the pump) will shift the operating point away from the high-efficiency range. Abnormal system resistance, such as partially closed valves and pipeline blockages, will also force the pump pressure to drop.
Long-term operation may cause impeller cavitation and seal aging. Failure to regularly clean the inlet filter screen and inspect bearing clearances will gradually degrade pump performance. Lishengde Energy-saving Pump Industry recommends establishing a three-level maintenance system: daily patrol inspection for seal leakage, monthly performance test to compare actual head with design values, and quarterly disassembly inspection to assess impeller wear.
Improper pipe diameter selection (oversized pipes lead to insufficient flow velocity, while undersized ones cause excessive local resistance), unreasonable pipeline layout (too many elbows or large elevation differences), and accumulated resistance from parallel components such as valves and filters will all impair the stability of pump pressure.
To guarantee the efficient operation of multistage pumps, Lishengde Energy-saving Pump Industry puts forward the following recommendations:
Provide full system parameters (flow-head curve and medium property report) during model selection;
Conduct dynamic balance test after installation (vibration ≤ 4.5 mm/s);
Establish digital operation and maintenance files to monitor pressure fluctuations in real time (the recommended threshold is ±5% of the designed value).