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Home > News| Some common problems in the use of pipeline pumps |
| Date: 2017-3-14 Hits: 1319 |
| What is a lift? What letter is it? What is the unit of measurement, and the formula of the pressure? A: lift is the unit weight of the liquid from the pump inlet to the outlet of the energy increment, for the volume of the pump, the energy increment is mainly reflected in the increase in pressure, so the pressure increment is usually replaced by the head to express. The efficiency of the pump is not an independent performance parameter, it can be calculated by other performance parameters such as flow rate, head and shaft power. On the contrary, it is known that the flow, lift and efficiency can also be used to calculate the shaft power. The pump head, including suction process, is similar to the pump outlet and inlet pressure difference. H with the head, the unit is m (m). The pressure of the pump by P, unit Mpa (Zhao Pa), H=P P. Such as P 1kgcm2, H= (lkgcm2) (1000kgm3) H= (1kgcm2) (M3 = 1000 kg) 1000 kg (10000 kg m2) m3=10m1Mpa=10kgcm2, H= (P2-P1) P (P2= P1= inlet pressure outlet pressure) What is the efficiency of the pump? Answer: refers to the effective power of the pump and shaft power ratio. ETA =PeP pump power usually refers to the input power, the motive power to the pump shaft, it is also called the shaft power, denoted by P. The effective power is the product of the pump head and mass flow and the acceleration of gravity. Pe= P gQH (W) or Pe= QH1000 (KW) gamma Rho: Pump density liquid (kgm3) gamma: pump liquid severe gamma = P G (Nm3) g (MS): the acceleration of gravity mass flow Qm= P Q (th or kgs) What is the cavitation margin? What is the suction process? Each unit of measurement that the letter? Answer: liquid pump at work in the impeller inlet will produce vapor due to a certain vacuum pressure, vaporization of the air bubbles in the liquid particle movement under the impact of erosion on the impeller, the metal surface, thus undermining the impeller and other metal, then vacuum pressure is called vaporization pressure, NPSH is excess vaporization pressure of surplus the energy position of the unit weight of the liquid in the pump suction port of. The unit with annotation, (NPSH) r with. The absorption process is necessary NPSH H: pump suction fluid allows the vacuum pump installation height is allowed, in meters. Suction = standard atmospheric pressure (10.33 m) - cavitation - Safety (0.5 m) standard atmospheric pressure pipeline vacuum height of 10.33 meters. For example: a pump necessary NPSH is 4 meters, for the absorption process of delta H solutions: Delta h=10.33-4.0-0.5=5.83 m? Among the various performance parameters of the pump are interdependent relationship between certain, you can pump through the test, the measured and calculated parameter values, and draw a curve, the curve is called the pump characteristic curve. Each pump has a specific characteristic curve, provided by the pump manufacturer. Typically, the characteristic curve of the plant is also marked with the recommended performance section, known as the working range of the pump. The actual operating point of the pump is determined by the curve of the pump and the pump device. Selection and use of the pump, the pump should be located in the operating range of the work to ensure the safety and economic operation. In addition, the same pump conveying viscosity of different liquids, the characteristic curve will change. Usually, the characteristic curve given by the pump manufacturer mostly refers to the characteristic curve of the cooling water. For the power pump, with the increase of the viscosity of the liquid, the head and efficiency are reduced, and the power of the shaft is increased, so the viscosity of the liquid is heated in the industry to reduce the viscosity, so as to improve the conveying efficiency. What are the characteristic curves of the pump? A: usually, the relationship between the main performance parameters curve is called characteristic curve or characteristic curve of centrifugal pump in essence, centrifugal pump performance curve is the movement rule of the liquid in the pump form, obtained by measurement. Characteristics include: (Q-H) flow lift curve, traffic - the efficiency curve (Q-), flow - power curve, flow rate (Q-N) - NPSH curve (Q- (NPSH) r), the performance curve of the pump flow is arbitrary, can find a set of relative to the head, in the the curve of power, efficiency and NPSH value, this set of parameters is called working state or condition, referred to as the point of maximum efficiency centrifugal pump working condition known as the best working condition, the optimum condition for general design point. The rated parameters of the general centrifugal pump is the design conditions and the best working conditions coincide or very close. In the selection of the efficiency of the interval operation, that is, energy saving, but also to ensure the normal operation of the pump, so it is important to understand the performance parameters of the pump. |
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