Pump type, series and model selection

Selection of Pump Type, Series, and Model Selection Criteria Physico-Chemical Performance of the Transport Media The physical properties of the transport media directly affect pump performance, materials, and construction, and are important factors to consider when selecting a model. The physico-chemical properties of the media include : Media name, media properties (eg corrosiveness, corrosion resistance, toxicity, etc.), solid particle content and particle size, density, viscosity, vaporization pressure, etc. The gas content of the prosthesis should also be listed where appropriate, Crystallization process parameters Process parameters is an important basis for pump selection, should be based on process and operation to determine the scope of change carefully. Flow Q flow refers to the production process equipment, pump required to convey the media, the process staff should be given normal, Minimum and maximum flow rate. Pump data sheets are usually only given normal and rated flow. Pumps are selected, the rated flow is not less than the maximum flow rate of the device, or remove 1.1 to 1.15 times the normal flow head H refers to the required process equipment Of the Yang Yang value, also known as the calculation of head. The general requirements of the pump rated head lift for the device required 1.05 to 1.1 times the inlet pressure Ps and outlet pressure Pd inlet and outlet pressure refers to the pump By the pressure at the flange, the size of the import and export pressure affect the shell pressure and shaft seal requirements.Temperature T refers to the inlet medium temperature of the pump, the pump should generally be given during the import medium normal, minimum and Maximum temperature NPSHa, also known as cavitation allowance, the measurement method, see Part II, Chapter 3. Operating conditions Operating conditions divided into continuous operation and intermittent operation of the two on-site conditions include on-site installation conditions of the pump (Indoor and outdoor), ambient temperature, relative temperature, atmospheric pressure, atmospheric corrosion and hazardous area classification conditions .Second, the choice of pump type Pump type should be based on the process parameters of the device, the physical and chemical properties of the transport medium, Operating cycle and structural characteristics of the pump and other factors reasonable choice.Figure 2 shows the pump type selection diagram for reference selection.According to the block diagram can initially determine the device parameters and medium characteristics of the pump requirements.Central pump has a simple structure, infusion No pulse, flow adjustment is simple and so on, so in addition to what circumstances should be selected as possible centrifugal pump.Measurement requirements, the selection of metering pumps .Head of high demand, the flow is small and without Small flow of high-lift centrifugal pump can be used, you can use the reciprocating pump, such as cavitation less demanding can also use the vortex pump. Head is very low, flow is large, the choice of axial flow pump and mixed flow pump. As of the larger viscosity (Greater than 650 ~ 1000mm2 / s), consider the choice of rotor pump or reciprocating pump; Viscosity particularly large, the choice of reciprocating pump medium gas content> 5%, the flow is smaller and the viscosity is less than 37.4mm2 / s, the optional If the flow is allowed to fluctuate, the reciprocating pump may be used, and pumps with self-priming performance, such as self-priming centrifugal pump and self-priming vortex pump, should be selected for occasions with frequent start-up or inconvenience of filling pump. Pump series and material selection Pump series refers to the pump plant to produce the same type of structure and use of pumps, such as IS-type Water Pump, Y-type pump, ZA chemical process pump, SJA chemical process pump.When the pump type is determined , According to process parameters and media characteristics to choose the pump series and materials.If you determine the selection of centrifugal pump, you can further consider the following items: ① According to the media decided to choose what characteristics of the pump, such as water pumps, corrosion-resistant pumps, Or chemical process pumps and impurity pumps, etc. The medium is highly toxic, valuable or radiation Sexual, etc. should not be allowed to leak material, should consider the choice of non-leak pump (such as shielded pump, magnetic pump) or with leakage of liquid collection and leak alarm device double-ended mechanical seal .If the medium is liquefied hydrocarbon and other volatile liquid should choose the end Nose residual allowance pump, such as cylinder pump.②According to the site installation conditions choose horizontal pump, vertical pump (including liquid pump, pipe pump) .③According to the flow rate of single suction pump, double suction pump, or flow centrifugal Pumps. ④ According to the level of head selection single suction pump, suction pump, or high-speed centrifugal pump. After determining the above can be based on different types of pumps in different pumps in different series of different pump characteristics and the conditions of the production plant, choose the right Pump series and production plant.If you determine the selection of single-stage horizontal chemical process pump, you can consider the edge pump factory SJA type, Bianfeng pump factory CZ type, ZA type, and the domestic general-purpose design IH chemical process pump and so on. Finally, according to the characteristics of the device and pump process parameters, to decide which type of manufacturing, testing standards.If the requirements are high, the optional API610 standard, the general requirements, optional GB5656 (ISO5199) or ANSIB73.1M standard. After using the metering pump, you can further consider the following items : When the medium is flammable, explosive, highly toxic and valuable liquid, often use the diaphragm pump.In order to prevent diaphragm rupture, the medium mixed with hydraulic oil cause accident, the optional double diaphragm metering pump with diaphragm rupture alarm device. The adjustment is generally manual, if you need to automatically adjust the choice of electric or pneumatic adjustment. Fourth, the pump model to determine the type of pump, series and material selection can be based on pump samples and information provided to determine the pump model and Specifications Positive displacement flow rate Q and rated outlet pressure P Determine the rated flow rate Q General direct maximum flow, such as the lack of maximum flow value, take the normal flow of 1.1 to 1.15 times the rated outlet pressure P Refers to the maximum pressure value that may appear at the pump outlet Check the volumetric flow pump [Q] and pressure [P] flow volume [Q] refers to the maximum flow of positive displacement pump output can be adjusted by bypass and Change and other methods to achieve process flow requirements.Pressure [P] refers to the maximum allowable outlet displacement displacement pump.Selection criteria is the initial determination of the pump model flow Q≤ [Q], and Q is closer to [ Q] healing ; Pressure P≤ [P], and P is more close to the [P] Healing .Check the pump NPSH required pump NPSHr NPSHa NPSHa, if not meet the requirements, Reduce the installation height of the pump to increase the NPSHa value or request to the pump plant to reduce the NPSHr value or use both of the above methods to finally make NPSHr <NPSHa-safty S. When more than one pump complies with the above conditions When considering the choice of high efficiency, low cost and reliability of the pump. Centrifugal pump model to determine the rated flow and lift to determine the rated flow is generally directly use the maximum flow, such as the lack of maximum flow value, often take the normal flow of 1.11.15 Times the rated head generally take 1.05 ~ 1.1 times the head of the device required.For the viscosity> 20mm2 / s or medium containing solid particles, need to be converted into the rated flow and lift when conveying water, to do some work. Figure According to the rated flow and lift to identify the initial choice of pump models, may be 1 species, it may be more than 2. Check according to the performance curve of the pump rated operating point falls in the pump efficient work area; check Pump NPSHa NPSHa NPSHr must be satisfied If not meet the requirements.When not meet, should take effective measures to achieve.Where meet the above two or more specifications, to choose the highest overall index for the final selected pump model.Can be more specific parameters: efficiency (pump efficiency High for the excellent), weight (light weight of the pump is superior) and the price (the pump is low for the best) is n = 1450r / minns = 3.65Q1 / 2 / H3 / 4 viscosity ≤ 37.4mpa.sQ ≤ 10m3 / hH≤150m Gas content> 5% H≤20mns> 300Q≤600m3 / H Viscosity> 650mpa.s Metering requirement Yes Yes Yes Yes Yes Yes Yes No No No No No No No No No Metering pump out of range Positive displacement pump Vortex pump Centrifugal pump Mixed flow pump axial flow pump

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