Pump selection issue

It is usually selected based on the medium, operating conditions, flow rate, and head.

Based on the physical and chemical properties of the medium being transported, as well as operating conditions, there is a selection table specific to each type of pump. Take your time to understand this; if you need any assistance, call me at 15151835174 or via QQ at 421866318

I generally agree with the above views; the operating conditions (medium, temperature, viscosity), the required flow rate and head, as well as the pipeline pressure loss, need to be determined.

III. Selection of pump type 1. When metering is required, a metering pump should be used. 2. When a very high head is required, the flow rate is low, and no suitable centrifugal pump with a high head for low flow rates is available, a reciprocating pump can be used. Vortex pumps can also be chosen when high cavitation requirements are not necessary. 3. When the head is very low and the flow rate is high, axial flow pumps and mixed-flow pumps can be used. 4. When the medium viscosity is high (greater than 650–1000 MM2/S), a rotary pump or reciprocating pump can be considered ； When the viscosity is particularly high, specially designed high-viscosity rotor pumps or high-viscosity reciprocating pumps can be used. 5. When the gas content in the medium is >5%, the flow rate is low, and the viscosity is less than 37.4 mm2/s, a vortex pump can be used. If pulsation in the flow rate is allowed, a reciprocating pump can be used. 6. In applications where starting is frequent or where it is difficult to fill the pump, pumps with self-priming capabilities should be used, such as self-priming centrifugal pumps, self-priming vortex pumps, and positive displacement pumps.

Generally, the pump is selected after knowing the properties of the material (density, dynamic viscosity, operating temperature, operating pressure, and local weather conditions)

The selection should be based on the viscosity and flow rate of the medium; refer to the chapter on pumps in chemical engineering machinery, where there is a chart

Key points for pump selection: The selection of a pump involves taking into account the operating environment and conditions in which the pump will function, the performance parameters necessary for its proper operation, as well as the physical and chemical properties of the medium to be transported. It is also essential to consider the technical performance criteria of the pump within the overall pumping system, the material used for the pump, the suitability of the motor, the reliability of the sealing system, as well as economic factors such as energy efficiency and ease of maintenance. Based on all these considerations, the most appropriate type and model of pump can be selected from the available options. Principles for pump selection (1) Principle of meeting process parameters: 1. Flow rate: If the process requirements specify the rated, minimum, and maximum flow rates for the pump, then the maximum flow rate should be used as a basis for selecting the pump ； When the maximum flow rate is not specified, 1.1 times the rated flow rate should generally be used as a reference. 2. Head: When selecting the head value for a pump, attention should be paid to the lowest liquid level at the suction side and the highest liquid level at the discharge side, with a margin left for safety ； Generally, the rated head of the pump selected is 1.05 to 1.1 times the head required by the installation. 3. Temperature: When specifying the rated, minimum, and maximum temperatures of the medium at the pump inlet during the process, the maximum temperature should be used as the reference. 4. Pressure: Refers to the inlet and outlet pressures, namely the pressures at the flanges of the pump’s inlet and outlet connections. The levels of these inlet and outlet pressures influence the pressure resistance required of the casing, as well as the choice of shaft seals and cooling systems. 5. NPSH of the unit: Based on the process characteristics and the layout requirements of the unit’s equipment, an initial value for the required NPSH of the pump is determined. Then, based on the cavitation curve of the selected pump, the required net positive suction head and the installation height of the equipment are determined, after which the net positive suction head for the system is calculated. Note: If viscous liquids or sewage containing particles are being transported, the process parameters must be converted to those under clean water conditions in order to select the appropriate pump. (2) Meet the requirements related to the properties of the liquid to be transported. For corrosive liquids: 1. The components involved in fluid flow within the pump, as well as the shaft seals, must meet the corrosion requirements (pH value) of the liquid being transported ； 2. Components exposed to highly corrosive liquids should be made of non-metallic materials, such as ceramic fiberglass, F46, graphite, etc ； 3. When corrosive liquids contain particles, the components that come into contact with these fluids should be made of metal materials that are both corrosion-resistant and wear-resistant, such as high-silicon cast iron, stainless steel, high-nickel alloys, titanium alloys, etc ； 4. Under normal circumstances, corrosion-resistant metal pumps have better wear resistance, pressure resistance, and high-temperature resistance compared to non-metallic pumps, while corrosion-resistant non-metallic pumps offer superior corrosion resistance than metal pumps. Leakage of liquid substances is not permitted: Liquids that are toxic, flammable, explosive, or have unpleasant odors, as well as valuable fluids, must be handled in such a way that leakage is prevented. It is necessary to ensure that the sealing parts of the pumps are safe and reliable; alternatively, shielded pumps, magnetic drive pumps, diaphragm pumps, etc., can be used. Liquids containing solid particles: 1. Different flow-through components should be selected based on the size and proportion of solid particles present in the liquid to be transported ； 2. When the liquid being transported contains large and numerous solid particles, pumps with a clog-resistant design can be chosen, such as vortex pumps or single-channel impeller pumps ； 3. Select the material for the flow-through components based on the hardness, content, and corrosiveness of the solids present in the liquid to be transported. Liquids containing long fibers: 1. The flow-through components feature a design with tearing and cutting functions to prevent the impeller from getting entangled by long fibers ； 2. Consider the mechanical characteristics of the motor to be used (overload capacity, etc.). Liquids at high temperature and high pressure: 1. The components exposed to flow should be made of materials resistant to high temperature and high pressure ； 2. Consider the requirements regarding the mechanical strength of components exposed to high temperatures and pressures, as well as the effects of thermal expansion ； 3. Select shaft seals and cooling systems that can withstand high temperatures and pressures. Viscous liquids: 1. A rotary pump can be used, such as a reciprocating pump or a screw pump ； 2. For high-viscosity liquids, specially designed high-viscosity screw pumps, gear pumps, and high-viscosity reciprocating pumps can be used. (3) Principle of meeting the environmental conditions at the pump’s installation site. Installation location: 1. Influence of the altitude in terms of geographical location ； 2. Choose horizontal, vertical, single-stage, or multi-stage based on the installation conditions ； 33. Is the pump installed indoors, outdoors, on the ground, or underwater? ； It is necessary to consider the submersion depth as well as the depth at which the pump operates underwater, depending on whether it is a single-pump unit or one that includes the motor and dives underwater together ； 4. Effects of vibration, shock, etc. at the pump installation site. Environmental conditions: 1. Ambient temperature: The pump may be used at temperatures lower than “#$%”; the risk of cold brittleness in the pump must be taken into account, and materials resistant to low temperatures should be used ； The pump structure type selected is a cylindrical double-shell centrifugal pump ； 2. Environmental noise: Pumps are required to have low noise levels; it is necessary to consider using a sliding bearing design as well as a hydraulic configuration that reduces noise, along with low-noise electric motors ； 3. Relative humidity: When using in an environment with high humidity, corrosion of the pump must be taken into account, and anti-corrosion measures should be implemented. The protection rating of the motor to be used also needs to be considered ； 4. Atmospheric pressure and atmospheric corrosion. Grid conditions: 1. Grid frequency (60Hz abroad (frequency details)) ； 2. Is the grid capacity sufficient? ； 3. Whether the grid voltage is three-phase (380V), single-phase (220V), or of varying voltages (including high voltages above 660V); the range of variation in the supply voltage ； 4. AC and DC of the power supply ； 5. Voltage drop due to the distance between the power source and the location where the pump is used (long-distance cable transmission). Division of hazardous areas: 1. Consider whether slight leaks or seepages are permissible during pump operation, as well as whether the liquid being transported is flammable or explosive ； 2. The selection of the power source for the pump and the explosion-proof rating of the motor: in areas where explosive gases are present, explosion-proof motors that match the classification of those areas must be used. In addition to the above three principles, economic factors such as the pump’s efficiency (energy savings), quality, installation and maintenance requirements, and price (cost) should also be considered comprehensively. For applications with special requirements, such as vacuum transport, high-temperature and high-pressure transport, or low-temperature transport, special types of pumps should be selected.