What is a water pump?

First, the definition of the pump What is the pump? Usually to enhance the liquid, liquid transport or increase the pressure on the liquid, that is, the mechanical energy of the prime mover into liquid energy to achieve the purpose of pumping liquid machine collectively referred to as the pump. Second, the pump classification According to the working principle can be divided into volume pumps, vane pumps and other common types. Volumetric pump is the use of changes in the volume of its studio to transfer energy, there are representative piston pump, piston pump, gear pump, diaphragm pump, screw pump, etc .; vane pump is the use of rotating blades and water to transfer energy, Representative of a centrifugal pump, axial flow pump and mixed flow pump. Submersible pump pump body part is a vane pump. In addition, other types of pumps have jet pumps, water hammer pumps, internal combustion pumps, water pump, respectively, using jet water hammer and fuel deflagration principle work. Turbine pump is a combination of turbine and vane pump, which directly uses the whereabouts of water as a motive force to run the water wheel to drive the pump connected to it. Third, the parameters of the pump What are the common parameters of the pump? What is the meaning? 1, flow Q flow is the amount of liquid delivered in a unit of time (volume or mass). Volume flow Q said, the unit is: m3 / s, m3 / h, l / s and so on. Mass flow Qm said, the unit is: t / h, kg / s and so on. The relationship between mass flow and volume flow is: Qm = ρQ, where ρ is the density of the liquid (kg / m3, t / m3), ρ = 1000kg / m3 at room temperature. 2, head H is the pump head pumping unit weight of liquid from the pump inlet to the pump outlet of the value of energy. Which is the effective energy of a Newtonian liquid through the pump. The unit is N · m / N = m, which is pumping liquid pumping column height, used to refer to as rice. 3, speed n speed is the number of revolutions of the pump shaft unit time, with the symbol n said unit is r / min. 4, NPSH pump NPSH pump at work at the impeller inlet at a certain vacuum pressure will produce vapors, vaporized bubbles in the liquid particle impact movement, the impeller and other metal surface erosion, thus undermining the impeller, etc. Metal, vacuum pressure at this time is called vaporization pressure, NPSH refers to the per unit weight of liquid in the pump inlet with excess energy than the vaporization pressure. Units marked with meters, with (NPSH) r. Suction stroke is required NPSH Δh: That is, the degree of vacuum that the pump allows liquid to be sucked in, that is, the allowable installation height of the pump, in meters. Stroke = standard atmospheric pressure (10.33 meters) - NPSH - safe amount (0.5 meters) Standard atmospheric pressure can depress the pipeline vacuum height of 10.33 meters. 5, power and efficiency Pump power is usually refers to the input power, that is, the prime mover shaft pump power, it is also known as shaft power, with P said; pump the effective power, also known as the output power, said Pe. It is the unit of time delivered from the pump liquid in the pump to obtain effective energy. Since the head is the unit of fluid that the pump outputs, it is the effective energy obtained from the pump so that the product of the head and the mass flow and the acceleration of gravity is the effective energy obtained from the liquid output from the pump per unit of time - the pump The effective power of the pump: Pe = ρgQH (W) = γQH (W), where ρ - pump delivery liquid density (kg / m3); γ - pump delivery liquid weight Of the flow (m3 / s); H - pump head (m); g - acceleration of gravity (m / s2). The difference between the shaft power P and the effective power Pe is the loss power in the pump, which is measured by the efficiency of the pump. Pump efficiency for the effective power and shaft power ratio, expressed with η. 6, the conversion of flow time per unit of time the volume of liquid discharged by the pump flow, flow Q said. Unit of measurement: m3 / h, l / s, L / s = 3.6 m3 / h = 0.06 m3 / min = 60 L / min G = Qρ G is the weight ρ is the liquid density : A pump flow of 50 m3 / h, seeking weight per hour pumping? Water density ρ 1000 kg / cubic meter. Solution: G = Qp = 50 × 1000 (m3 / h · kg / m3) = 50000kg / h = 50t / h 7, the relationship between lift and pressure and conversion unit weight The energy obtained by the liquid pump is called head. Pump head including the suction stroke, approximately pump outlet and inlet pressure difference. Head with H said, in meters (m). The pressure of the pump is expressed by P in units of Mpa (MPa), H = P / ρ, H = 1kg / cm2 / 1000kg / m3 if P is 1kg / (1000 kg / m3) = (10000 kg / m2) / 1000 kg / m3 = 10m1Mpa = 10kg / m2, H = P2- P1 / P2 (P2 = outlet pressure P1 = inlet pressure) Selection of new users how to choose the pump? What needs attention? 1, the principle of pump selection 1.1 must meet the requirements of the characteristics of the medium: the transmission of flammable, explosive toxic or precious medium pump requires shaft seal reliable or leak-free pump; for conveying corrosive media pump, convection parts require Corrosion-resistant materials. For pumps containing solid particulate media, convection components are required to be wear-resistant and if necessary, the shaft seal is flushed with a cleaning fluid. 1.2 to make the type and performance of the selected pump in line with the device flow, head, pressure, temperature, cavitation flow, suction stroke and other process parameters. 1.3 Mechanical reliability, low noise, small vibration. 1.4 Economic Consideration of equipment costs, operating costs, maintenance costs and management costs of the lowest total cost. 1.5 Centrifugal pump with high speed, small size, light weight, high efficiency, large flow, simple structure, infusion without pulsation, stable performance, easy operation and maintenance features such as convenience. Centrifugal pumps should be used as far as possible when there is no special need (need to measure, low head high flow, medium viscosity, frequent start and inconvenient filling). 1.6 for horizontal vertical pump selection should be based on design and installation of pump room space to decide. 2, pump selection 2.1 flow. Flow is one of the important performance data of the pump, which is directly related to the delivery capacity of the entire device. Such as the design process can be calculated in the pump normal, minimum, maximum three kinds of flow. Select the pump, based on the maximum flow, taking into account the normal flow, in the absence of maximum flow, it is usually desirable to 1.2 times the normal flow as the maximum flow. 2.2 lift. Head as pump another important performance data, generally on the basis of the normal use of head left about 8% margin. 2.3 Media Properties. Mainly include the physical properties of the liquid medium (temperature, density, viscosity, medium particle diameter and gas content), chemical properties (mainly corrosive and toxic). Media properties mainly affect the pump material and the mechanical seal material. 2.4 diameter. Diameter, pipe diameter, the same flow, the flow velocity is small, the resistance loss is small, but the price is high; pipe diameter is small, the resistance loss increases dramatically, so that the selected pump lift, with belt power, cost and operation Costs have increased. Therefore, we should consider the selection of pipe diameter from the technical and economic point of view. 2.5 pipe layout. Piping should be as straight as possible to minimize pipes