Difference between submersible pumps and centrifugal pumps
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What’s the difference between these two? When is it applicable? If these two are used together, how should they be used? To pump water out of the foundation pit, is it the submersible pump that is used underwater, while the centrifugal pump is used on the ground? And what do 3 inches and 5 inches mean?
Submersible pumps can be placed underwater, while centrifugal pumps are placed on the ground; the size should then be determined by the diameter of the pipes connecting them. 1. Submersible pump: A water treatment tool with a very wide range of applications. Unlike ordinary pumps, it operates underwater, while most pumps work on the ground. Working principle of submersible pumps: Before starting the pump, the suction pipe and the pump itself must be filled with liquid. After the pump is started, the impeller rotates at high speed; the liquid inside rotates along with the blades. Under the effect of centrifugal force, the liquid is ejected outward from the impeller. As it moves through the diffusion chamber in the pump casing, its velocity gradually decreases while its pressure increases, before it finally flows out through the pump outlet and the discharge pipe. At this point, a vacuum low-pressure area devoid of both air and liquid is formed at the center of the blade as the liquid is flung outward. Under the effect of the atmospheric pressure at the surface of the liquid pool, the liquid flows into the pump through the suction pipe; in this way, the liquid is continuously drawn up from the pool and then continuously discharged through the outlet pipe. The basic parameters of submersible pumps include flow rate, head, pump speed, required power, rated current, efficiency, pipe diameter, and so on. The main uses and application areas of submersible pumps include drainage in construction projects, irrigation in agriculture, industrial water circulation, supply of water for urban and rural residents, and even emergency rescue operations.
2. Centrifugal Pumps: First, let’s understand what centrifugal force is. Centrifugal force is actually a manifestation of an object’s inertia. For example, with water droplets on an umbrella, when the umbrella rotates slowly, the droplets rotate along with it; this is because the friction between the umbrella and the droplets acts as a centripetal force that keeps the droplets in motion. But if the umbrella rotates faster, this friction is no longer sufficient to keep the droplets in circular motion, and they will fall off the umbrella and move toward its edges. It’s similar to using a rope to make a stone move in a circular path – if the speed is too high, the rope will break and the stone will fly away. This is what is meant by centrifugal force. Centrifugal pumps are designed based on this principle: the rapidly rotating impeller blades drive the water, causing it to be ejected outward, thereby achieving the purpose of transportation. There are various types of centrifugal pumps. Based on their use, they can be classified as domestic or industrial pumps; based on the type of fluid they transport, they can be categorized as clean water pumps, pumps for handling debris, corrosion-resistant pumps, etc. The basic structure of a centrifugal pump consists of six parts, namely: the impeller, the pump casing, the pump shaft, the bearings, the sealing ring, and the stuffing box. 1. The impeller is the core component of a centrifugal pump; it features high speed and high power, and the blades on the impeller play a key role. The impeller must undergo a static balance test before being assembled. The inner and outer surfaces of the impeller must be smooth to reduce frictional losses in the water flow. 2. The pump body, also known as the pump casing, is the main component of a water pump. It serves a supporting and fixing function, and is connected to the bracket that holds the bearing. 3. The function of the pump shaft is to connect to the motor via a coupling, thereby transmitting the torque of the motor to the impeller; it is therefore the main component for transferring mechanical energy. 4. Bearings are components that are fitted on the pump shaft to support it; there are two types: rolling bearings and sliding bearings. Rolling bearings use butter as a lubricant, and the amount of lubricant applied should be appropriate – generally 2/3 to 3/4 of the bearing’s volume. Too much lubricant will cause heating, while too little will result in noise as well as heating! Sliding bearings use transparent oil as a lubricant, which should be filled to the oil level line. Too much oil seeps along the pump shaft and leaks away, while too little oil causes the bearings to overheat and get damaged, leading to accidents! During the operation of the water pump, the temperature of the bearings reaches up to 85 degrees; under normal conditions it is around 60 degrees. If this temperature rises, it is necessary to identify the cause (such as the presence of impurities, whether the oil has turned black, or if water has entered the system) and take prompt action! 5. The sealing ring is also known as a leak-reduction ring. An excessive gap between the impeller inlet and the pump casing allows water from the high-pressure area inside the pump to flow through this gap to the low-pressure area, which affects the pump’s flow rate and reduces its efficiency! Too small a gap can cause friction between the impeller and the pump casing, leading to wear. To increase backflow resistance, reduce internal leakage, and extend the service life of the impeller and pump casing, a sealing ring is installed at the junction between the inner edge of the pump casing and the outer periphery of the impeller; it is advisable to maintain the sealing gap between 0.25 and 1.10 mm. 6. The packing box is mainly composed of packing, a water seal ring, a packing barrel, a packing gland, and a water seal tube. The main function of the stuffing box is to seal the gap between the pump casing and the pump shaft, preventing the water inside the pump from leaking out and preventing outside air from entering the pump. Maintain a vacuum inside the water pump at all times! When heat is generated by the friction between the pump shaft and the packing, a water seal is used to channel water into the seal ring in order to cool the packing! Maintain the normal operation of the water pump. Therefore, special attention must be paid to the inspection of the stuffing box during the routine inspections of the water pump’s operation! The packing needs to be replaced after about 600 hours of operation. Working principle of centrifugal pumps: The working principle of centrifugal pumps is that, thanks to the high-speed rotation of the impeller, the liquid gains energy under the effect of inertial centrifugal force, which increases its pressure. Before the water pump starts operating, the pump body and the inlet pipe must be filled with water to prevent cavitation. When the impeller rotates rapidly, the blades cause the water to spin quickly; the spinning water is ejected from the impeller under the effect of centrifugal force. Once the water inside the pump is thrown out, a vacuum area is formed in the center of the impeller. The water from Suwon is pushed into the inlet pipe through the pipeline network under the action of atmospheric pressure (or water pressure). By repeating this cycle, continuous water pumping can be achieved. It is worth mentioning here that before starting a centrifugal pump, the pump casing must be filled with water before startup; otherwise, this will cause the pump to overheat, vibrate, and have a reduced flow rate, leading to damage to the pump (known as \"cavitation\") and resulting in equipment failures! Cavitation refers to the phenomenon where, when a centrifugal pump is started and there is air inside the pump, the low density of air results in a weak centrifugal force generated upon rotation; as a result, the low pressure created in the center area of the impeller is not sufficient to draw in liquid from areas below the pump inlet, preventing the transfer of fluid. There are many types of centrifugal pumps, and the common classification methods include the following: 1. Classified by the impeller suction method: single-suction centrifugal pump, double-suction centrifugal pump ； 2. Classified by the number of impellers: single-stage centrifugal pumps, multi-stage centrifugal pumps ； 3. Classified by impeller structure: open impeller centrifugal pump, semi-open impeller centrifugal pump, closed impeller centrifugal pump ； 4. Classified by operating pressure: low-pressure centrifugal pumps, medium-pressure centrifugal pumps, high-pressure centrifugal pumps ； 5. Classified by pump shaft position: horizontal centrifugal pumps and vertical centrifugal pumps. ISG domestic water supply pumps, pumps for domestic use, community water pumps, and domestic water supply and drainage equipment. These products are designed by combining the performance parameters of IS and IR type centrifugal pumps with the unique structure of vertical pumps, and they are manufactured in strict accordance with ISO2858 standards. Designed using high-quality domestic hydraulic models, they represent the ideal new generation of horizontal pump products. This product always uses a cemented carbide mechanical seal. Application range: The ISW type pump is suitable for industrial and municipal water supply and drainage applications, such as pressurizing water supply in high-rise buildings, garden irrigation, fire protection systems, long-distance water transport, HVAC systems, as well as for pressurization in bathrooms and other related equipment. Its operating temperature should not exceed 85°C. Pumps of the ISWR type are widely used for pressurizing and transporting boiler feed water in industries such as metallurgy, chemicals, textiles, and papermaking, as well as in restaurants, as well as in urban heating systems. The SGWR type can be used at temperatures not exceeding 120°C
2. Centrifugal Pumps: First, let’s understand what centrifugal force is. Centrifugal force is actually a manifestation of an object’s inertia. For example, with water droplets on an umbrella, when the umbrella rotates slowly, the droplets rotate along with it; this is because the friction between the umbrella and the droplets acts as a centripetal force that keeps the droplets in motion. But if the umbrella rotates faster, this friction is no longer sufficient to keep the droplets in circular motion, and they will fall off the umbrella and move toward its edges. It’s similar to using a rope to make a stone move in a circular path – if the speed is too high, the rope will break and the stone will fly away. This is what is meant by centrifugal force. Centrifugal pumps are designed based on this principle: the rapidly rotating impeller blades drive the water, causing it to be ejected outward, thereby achieving the purpose of transportation. There are various types of centrifugal pumps. Based on their use, they can be classified as domestic or industrial pumps; based on the type of fluid they transport, they can be categorized as clean water pumps, pumps for handling debris, corrosion-resistant pumps, etc. The basic structure of a centrifugal pump consists of six parts, namely: the impeller, the pump casing, the pump shaft, the bearings, the sealing ring, and the stuffing box. 1. The impeller is the core component of a centrifugal pump; it features high speed and high power, and the blades on the impeller play a key role. The impeller must undergo a static balance test before being assembled. The inner and outer surfaces of the impeller must be smooth to reduce frictional losses in the water flow. 2. The pump body, also known as the pump casing, is the main component of a water pump. It serves a supporting and fixing function, and is connected to the bracket that holds the bearing. 3. The function of the pump shaft is to connect to the motor via a coupling, thereby transmitting the torque of the motor to the impeller; it is therefore the main component for transferring mechanical energy. 4. Bearings are components that are fitted on the pump shaft to support it; there are two types: rolling bearings and sliding bearings. Rolling bearings use butter as a lubricant, and the amount of lubricant applied should be appropriate – generally 2/3 to 3/4 of the bearing’s volume. Too much lubricant will cause heating, while too little will result in noise as well as heating! Sliding bearings use transparent oil as a lubricant, which should be filled to the oil level line. Too much oil seeps along the pump shaft and leaks away, while too little oil causes the bearings to overheat and get damaged, leading to accidents! During the operation of the water pump, the temperature of the bearings reaches up to 85 degrees; under normal conditions it is around 60 degrees. If this temperature rises, it is necessary to identify the cause (such as the presence of impurities, whether the oil has turned black, or if water has entered the system) and take prompt action! 5. The sealing ring is also known as a leak-reduction ring. An excessive gap between the impeller inlet and the pump casing allows water from the high-pressure area inside the pump to flow through this gap to the low-pressure area, which affects the pump’s flow rate and reduces its efficiency! Too small a gap can cause friction between the impeller and the pump casing, leading to wear. To increase backflow resistance, reduce internal leakage, and extend the service life of the impeller and pump casing, a sealing ring is installed at the junction between the inner edge of the pump casing and the outer periphery of the impeller; it is advisable to maintain the sealing gap between 0.25 and 1.10 mm. 6. The packing box is mainly composed of packing, a water seal ring, a packing barrel, a packing gland, and a water seal tube. The main function of the stuffing box is to seal the gap between the pump casing and the pump shaft, preventing the water inside the pump from leaking out and preventing outside air from entering the pump. Maintain a vacuum inside the water pump at all times! When heat is generated by the friction between the pump shaft and the packing, a water seal is used to channel water into the seal ring in order to cool the packing! Maintain the normal operation of the water pump. Therefore, special attention must be paid to the inspection of the stuffing box during the routine inspections of the water pump’s operation! The packing needs to be replaced after about 600 hours of operation. Working principle of centrifugal pumps: The working principle of centrifugal pumps is that, thanks to the high-speed rotation of the impeller, the liquid gains energy under the effect of inertial centrifugal force, which increases its pressure. Before the water pump starts operating, the pump body and the inlet pipe must be filled with water to prevent cavitation. When the impeller rotates rapidly, the blades cause the water to spin quickly; the spinning water is ejected from the impeller under the effect of centrifugal force. Once the water inside the pump is thrown out, a vacuum area is formed in the center of the impeller. The water from Suwon is pushed into the inlet pipe through the pipeline network under the action of atmospheric pressure (or water pressure). By repeating this cycle, continuous water pumping can be achieved. It is worth mentioning here that before starting a centrifugal pump, the pump casing must be filled with water before startup; otherwise, this will cause the pump to overheat, vibrate, and have a reduced flow rate, leading to damage to the pump (known as \"cavitation\") and resulting in equipment failures! Cavitation refers to the phenomenon where, when a centrifugal pump is started and there is air inside the pump, the low density of air results in a weak centrifugal force generated upon rotation; as a result, the low pressure created in the center area of the impeller is not sufficient to draw in liquid from areas below the pump inlet, preventing the transfer of fluid. There are many types of centrifugal pumps, and the common classification methods include the following: 1. Classified by the impeller suction method: single-suction centrifugal pump, double-suction centrifugal pump ； 2. Classified by the number of impellers: single-stage centrifugal pumps, multi-stage centrifugal pumps ； 3. Classified by impeller structure: open impeller centrifugal pump, semi-open impeller centrifugal pump, closed impeller centrifugal pump ； 4. Classified by operating pressure: low-pressure centrifugal pumps, medium-pressure centrifugal pumps, high-pressure centrifugal pumps ； 5. Classified by pump shaft position: horizontal centrifugal pumps and vertical centrifugal pumps. ISG domestic water supply pumps, pumps for domestic use, community water pumps, and domestic water supply and drainage equipment. These products are designed by combining the performance parameters of IS and IR type centrifugal pumps with the unique structure of vertical pumps, and they are manufactured in strict accordance with ISO2858 standards. Designed using high-quality domestic hydraulic models, they represent the ideal new generation of horizontal pump products. This product always uses a cemented carbide mechanical seal. Application range: The ISW type pump is suitable for industrial and municipal water supply and drainage applications, such as pressurizing water supply in high-rise buildings, garden irrigation, fire protection systems, long-distance water transport, HVAC systems, as well as for pressurization in bathrooms and other related equipment. Its operating temperature should not exceed 85°C. Pumps of the ISWR type are widely used for pressurizing and transporting boiler feed water in industries such as metallurgy, chemicals, textiles, and papermaking, as well as in restaurants, as well as in urban heating systems. The SGWR type can be used at temperatures not exceeding 120°C
The issue of the filling pump also needs to be considered. The submersible pump is placed underwater, so there’s no need to worry about this
Submersible pumps can be considered a type of centrifugal pump. They were developed taking into account factors such as the installation location, protection rating, and self-priming capability.