The performance of the pump, the performance parameters […]
The performance of the pump, the performance parameters of the pump, and the performance of the pump. Which parameters are used to represent the performance of the pump? What is the flow rate of the pump? Flow refers to the volume or weight of the liquid delivered by the pump per unit time. Expressed by Q, the commonly used units are m3/h, m3/s, L/s or t/h. The flow rate on the nameplate of the pump is the design flow rate of the pump, which is referred to as the rated flow rate. The pump runs most efficiently at this flow rate. The performance parameters of the water pump 2. What is the lift of the pumpChina Mixer Pumps manufacturer?
The lift refers to the energy added by the unit gravity liquid from the pump inlet to the outlet, that is, the energy obtained by the unit gravity water after passing through the pump. Expressed by H, the unit is mH2O, generally referred to as m. The head on the nameplate of the pump is the design head of the pump, which corresponds to the head when passing the design flow, also known as the rated head. The performance parameters of the water pump 3. What is the power of the water pump? Power refers to the work done by the water pump per unit time, in KW. 1. The effective power of the water pump The effective power, also known as the output power of the water pump, refers to the energy obtained from the water pump by the liquid flowing through the water pump per unit time. Expressed by Pu. 2. Shaft power Shaft power, also known as the input power of the water pump, refers to the power delivered by the power machine to the water pump shaft. Expressed by P. The shaft power on the nameplate of the pump refers to the shaft power corresponding to the design flow, also known as the rated shaft power. 3. Matching power Matching power refers to the power of the power machine matched with the water pump, expressed by P. Generally, the matching power value is marked on the pump nameplate or sample. Performance parameters of the water pump 4. What is the efficiency of a water pump? Efficiency refers to the percentage of the ratio of the effective power of the water pump to the shaft power. It marks the effective degree of energy conversion of the water pump and is an important technical and economic indicator of the water pump, expressed by η. The efficiency on the pump nameplate corresponds to the efficiency when the design flow is passed, and this efficiency is the highest efficiency of the pump. The higher the efficiency of the pump, the smaller the energy loss when the pump is working.
The shaft power of the water pump cannot be completely transferred to the output liquid, and a part of the energy must be lost. The energy loss in the water pump can be divided into three parts, namely hydraulic loss, volume loss and mechanical loss. 1. Hydraulic loss and hydraulic efficiency When water flows through the suction chamber, impeller, and pressure out chamber of the pump, friction loss, local loss and impact loss will occur. The friction loss is the loss caused by the frictional resistance between the water flow and the wall of the flow-through component. The local loss is the loss of the water flow in the pump due to changes in the speed and direction of the water flow. The impact loss is the loss caused by the water flow at the inlet and outlet of the blade and the pressure chamber when the pump is operating under non-design conditions. The greater the hydraulic loss, the smaller the head of the pump.
The head without considering the hydraulic loss in the pump is the theoretical head HT, and the ratio of the pump head H to the theoretical head H to the theoretical head HT is called the hydraulic efficiency ηh. 2. After the volume loss and volume efficiency water flows through the impeller, a small part of the high-pressure water leaks to the inlet of the impeller through the clearance in the pump body (such as the leakage ring) and the axial force balance device (such as the balance hole), and another part from the shaft The sealing device leaks out of the pump body, which consumes a part of energy, that is, volume loss. The larger the leakage q, the smaller the water output Q of the pump. The ratio of the flow rate Q through the pump outlet to the flow rate Q+q through the pump inlet is called the volumetric efficiency ηV. 3. Mechanical loss and mechanical efficiency When the impeller rotates in the liquid, the outer surface of the front and rear cover plates and the liquid produce friction loss (that is, the wheel loss). When the pump shaft rotates, the shaft, the shaft seal, and the bearing produce friction loss to overcome the friction loss. Part of the energy is consumed, that is, mechanical loss. The mechanical loss power is represented by Pm. After deducting the mechanical loss from the input power of the pump, the power transmitted by the impeller to the liquid is called water power, which is represented by Pw. The efficiency of a water pump is the product of volumetric efficiency, hydraulic efficiency and mechanical efficiency. To improve the efficiency of water pumps, various losses in the water pump must be reduced. To improve the efficiency of water pumps, in addition to improving and improving the hydraulic model, material selection, processing technology, components, etc., the user must also pay attention to the correct selection of pump type, ensure the installation quality, reasonably adjust the operating conditions and strengthen maintenance management. Make the water pump often run in a high-efficiency state to achieve the purpose of saving energy, reducing costs and improving economic benefits. The performance parameters of the water pump 5. What is the water absorption performance of the water pump? It is the parameter that characterizes the water absorption performance of the water pump. When designing the pumping station, it is necessary to determine the installation elevation of the pump according to the water absorption performance parameters. The allowable suction height is expressed by Hs, and the necessary cavitation allowance is expressed by (NPSH)r, and the unit is m. The performance parameters of the water pump 6. What is the speed of the pump? The speed refers to the number of times the pump shaft rotates per minute, expressed by n, and the unit is r/min. The speed on the nameplate is the design speed of the pump, also known as the rated speed. The speed is an important parameter that affects the performance of the water pump. When the speed changes, the other five performance parameter tables of the water pump all change accordingly.