A type of centrifugal pump, characterized by suction inlets on both sides of the impeller; fluid enters the pump cavity from both sides simultaneously. The pump body is mostly horizontally split, facilitating disassembly and maintenance, and is equipped with symmetrical suction flow channels, with a larger number of components.
Has a suction inlet only on one side of the impeller; fluid enters the pump body unidirectionally. The pump body is mainly end-suction or volute-type, with a more compact structure, fewer components than double-suction pumps, and no symmetrical suction flow channel design.
Double-suction pumps adopt a bidirectional suction design, where fluid enters evenly from both sides of the impeller, which can effectively reduce the pressure difference between the two sides of the impeller and lower the probability of cavitation. Single-suction pumps use unidirectional suction, and fluid tends to form pressure fluctuations on one side of the impeller when entering, especially under high-flow conditions, the cavitation risk is relatively higher. In addition, the suction flow channel design of double-suction pumps is more in line with fluid mechanics principles, resulting in smaller resistance loss when fluid enters the pump cavity; the suction flow channel of single-suction pumps is limited by structure, so the resistance loss is usually greater than that of double-suction pumps, and the installation requirements for the suction pipeline are more stringent.
In terms of flow rate, relying on the bidirectional suction advantage, the flow rate of double-suction pumps is usually 1.5-2 times that of single-suction pumps under the same impeller diameter and speed, suitable for large-flow transportation scenarios such as urban water supply and large-scale water conservancy projects. Single-suction pumps have a narrower flow range, more suitable for small and medium flow requirements, such as industrial circulating water systems and small irrigation equipment. In terms of head performance, due to the symmetrical force on the impeller, double-suction pumps can achieve higher heads by increasing the impeller diameter or speed, but limited by the structure, they are not as good as multi-stage single-suction pumps in ultra-high head scenarios. Single-suction pumps have lower single-stage heads; if high heads are required, multi-stage design is needed, but the volume and maintenance cost of multi-stage single-suction pumps will increase accordingly.
The Net Positive Suction Head Required (NPSHr) is 20%-30% lower than that of single-suction pumps of the same specification; the flow velocity distribution at the impeller inlet is uniform, the probability of forming local low-pressure areas is low, and it can operate stably at a lower suction liquid level height, with looser restrictions on the installation height of the suction pipeline.
The required cavitation margin is relatively high; if the suction conditions are poor (such as low suction liquid level and large pipeline resistance), cavitation is prone to occur, leading to pump body vibration and increased noise. Long-term cavitation will damage the impeller and affect the service life of the equipment.
Double-suction pumps have a relatively complex structure, including horizontally split pump bodies, symmetrical impellers, double-end seals and other components, with high assembly precision requirements. During daily maintenance, the horizontally split pump body needs to be disassembled, the maintenance cycle is long, and the maintenance cost is about 1.2-1.5 times that of single-suction pumps. Single-suction pumps have a simple structure and a small number of components; for example, end-suction single-suction pumps only need to disassemble the front end cover to replace seals or inspect the impeller, with simple maintenance procedures and lower maintenance costs. From the perspective of long-term use, single-suction pumps have more cost advantages in small and medium flow, low maintenance demand scenarios, while double-suction pumps can only reflect their value in large flow, high reliability demand scenarios.
With wide flow channels and bidirectional suction design, it has stronger adaptability to media and can transport fluids containing a small amount of impurities (solid particle content ≤3%) such as river water and industrial wastewater; the symmetrical structure can reduce the scouring of the pump body by the medium, suitable for liquids with low corrosiveness.
The flow channel is narrow, especially the flow channel of small-flow models is easy to be blocked by impurities, so it is only suitable for transporting clean fluids such as clear water and solvents; if it is necessary to transport media containing impurities, additional filtering devices must be installed, otherwise faults are easy to occur, increasing equipment investment and operation resistance.
Due to the horizontally split structure and the horizontal arrangement of suction and discharge pipelines, double-suction pumps have a large overall floor area and usually require reserved large installation space, especially in the application of large double-suction pumps, there are clear requirements for the size of the machine room. Single-suction pumps have a compact structure; end-suction single-suction pumps can be installed vertically or horizontally, the floor area of horizontal single-suction pumps is only 60%-70% of that of double-suction pumps with the same flow rate, and vertical single-suction pumps can save horizontal space, suitable for scenarios with limited installation space, such as small industrial plants and circulating water systems of high-rise buildings.
The impeller is symmetrically stressed, radial forces cancel each other out during operation, the radial load of the pump shaft is small, and the bearing wear rate is slow; under rated working conditions, the vibration speed is ≤2.8mm/s, the noise value is lower than 85dB, and the operation stability is high.
The impeller is stressed on one side, the radial force is large, which is easy to cause bearing heating and wear during long-term operation; the vibration speed is mostly between 3.5-5mm/s, the noise value is 5-10dB higher than that of double-suction pumps, and the operation stability and mute effect are weaker than double-suction pumps.
In terms of purchase cost, under the same flow specification, the price of double-suction pumps is usually 1.3-1.8 times that of single-suction pumps, because double-suction pumps have complex structures, large material consumption and high manufacturing process requirements. Single-suction pumps have lower purchase costs, suitable for small and medium flow projects with limited budgets. In terms of operating cost, the efficiency of double-suction pumps is usually 3%-5% higher than that of single-suction pumps, and the electricity saving effect is significant in long-term large-flow operation scenarios. Single-suction pumps have lower efficiency, but in small and medium flow, intermittent operation scenarios, the operating cost difference is not large. In terms of maintenance cost, as mentioned earlier, double-suction pumps have long maintenance cycles and high costs, while single-suction pumps are more economical to maintain. Enterprises need to comprehensively evaluate the cost based on the project life cycle.
When selecting a pump, priority should be given to flow requirements: for large-flow scenarios (usually ≥200m³/h), such as urban main road water supply and large power plant circulating water systems, double-suction pumps are preferred; for small and medium flow scenarios (≤150m³/h), such as small factory cooling systems and home irrigation, single-suction pumps are more suitable. Secondly, look at the cavitation conditions; if the suction liquid level is low and the pipeline resistance is large, double-suction pumps are a better choice; when the suction conditions are good and there are no special cavitation requirements, single-suction pumps can be selected. In addition, it is also necessary to consider factors such as installation space, maintenance cost and medium characteristics: single-suction pumps are selected for limited installation space, and double-suction pumps are selected for requirements of high operational stability and low noise; single-suction pumps are selected for transporting clean fluids, and double-suction pumps can be considered for transporting fluids containing a small amount of impurities or low corrosiveness. Only by comprehensively evaluating various factors can the most suitable pump type be selected to ensure efficient and stable operation of the system.
This article clearly compares the core differences between double-suction pumps and single-suction pumps, providing a basis for pump selection in different scenarios. As a professional pump enterprise, TEFFIKO is deeply in line with the technical points of the two types of pumps, and its products have both efficient performance and stable quality, which can adapt to diverse needs such as large flow and low cavitation, small and medium flow and compact installation. Whether it is the first selection that needs to accurately match the working conditions or equipment upgrade to seek better solutions, TEFFIKO can provide reliable support with rich experience and customized services. Choosing TEFFIKO twice is a double guarantee for efficient operation and long-term value.
