Full Guide on Installation and Maintenance of Submersible Pumps: Analysis of Selection and Design Key Points

Overview of Submersible Pumps
Submersible sewage pumps, also known as submersible sewage discharge pumps, are innovative designs based on submersible pumps. Their channels specifically adopt anti-clogging technology, suitable for various applications such as first-stage lifting, intermediate lifting, and sludge return. This type of pump is widely used in municipal engineering, building construction, industrial sewage discharge and wastewater treatment, etc., and can effectively discharge sewage, wastewater and rainwater containing solids and long fibers.
Installation method and features
Coupled installation
The installation method of submersible pumps is flexible and diverse, and their flow coverage range is extensive. Therefore, they have become indispensable lifting equipment in water treatment projects, and are particularly favored in small and medium-sized projects. Through coupling connection, the pump and the outlet pipeline can be easily separated, providing great convenience for the maintenance of the pump. With the lifting device, the pump can be lifted easily. Coupled installation is suitable for various specifications of submersible pumps, and the coupler is usually provided as a complete set by the equipment manufacturer, simplifying the installation process.
Mobile installation
Through a hose connection, the outlet pipeline of the pump is directly connected to the equipment on the water surface via a hose. The submersible pump is placed at the bottom of the water tank by its own weight or suspended on a lifting device via iron chains, etc. This installation method does not require a coupling device or a pool bottom fixation, making it very convenient for movement. However, it should be noted that due to the limitations of the installation method itself, it is difficult to withstand large torques, so it is mainly suitable for small submersible pumps.
Accessories and Design Description
After the model selection is confirmed, the manufacturer of the submersible pump will provide a detailed installation condition diagram. The designers need to carefully read and understand the meanings of each dimension and symbol to ensure that the submersible pump can be installed and put into use correctly and safely.
Installation requirements and conditions
Minimum operating liquid level
For submersible pumps with a power of 11kW or more, it is generally recommended to equip a motor cooling system to ensure the safe operation of the pump. The cooling method affects the minimum liquid level requirement, and thus the symbol will also be different. The direct cooling method requires a higher liquid level. In the installation condition diagram provided by the manufacturer, these two cooling methods are distinguished by different symbols. Among them, "▼" indicates the situation with a cooling system, while "▽" indicates the situation without a cooling system. Taking a certain case as an example, when there is a cooling system, the effective minimum liquid level distance from the bottom of the coupling device is 570mm, while without a cooling system, this distance is 785mm.
Planar opening and positioning
When installing a coupled submersible pump, specific dimensions and positioning references must be followed to ensure stable operation. For example, in a certain case, the A view clearly indicates that the minimum installation hole size of the pump is 1000×700mm. During the positioning process, the edge of the pool was set as the reference line because the positioning of the submersible pump mainly depends on the connecting rod that is coupled with the coupling device. At the same time, when determining the position of the coupling base bolts, the pool edge should also be used as the reference for positioning. According to the instructions in the case, the position of the bolt hole 253mm away from the pool edge should be determined first, and then the positions of other bolt holes can be determined based on the bolt hole spacing of 350mm.
The most crucial dimensions that need to be clearly marked on the drawings include: the position and size of the openings on the top surface, as well as the location and specifications of the embedded anchor bolts at the bottom (usually designed with reserved holes and poured concrete). The fixation of the top guide rods is typically done using expansion bolts.
Electrical protection measures
Since the submersible sewage pumps operate in a submerged environment, there is a risk of damage to the pumps due to water leakage and other factors. Therefore, various protective measures need to be taken for prevention. Taking a certain submersible sewage pump manufacturer as an example, the protective measures they provide include, but are not limited to: pumps with a power of 5kW and below are equipped with motor winding overheating protection components and water leakage probes to ensure that the motor can be stopped in abnormal situations in time. For pumps with a power of 11kW and above, in addition to these, float switches and additional water leakage probes are also added to provide more comprehensive protection.
These protective components sense the temperature within the motor stator windings. Once the temperature reaches the set value, it will trigger the overheat protection device of the control cabinet, thereby stopping the motor. Meanwhile, the water leakage sensor and the float switch are respectively used to detect the water leakage on the motor side and the failure of the mechanical seal, ensuring that an alarm can be promptly triggered and the machine stopped upon detecting water ingress. During the electrical installation process, the electrical control cabinet must be designed according to the selection criteria and the electrical requirements provided by the manufacturer to ensure that these protective measures can function effectively.