What issues should be noted during the installation and maintenance of a double-suction, centerline-split pump?

　　 Double-suction mid-section pump In municipal water supply and drainage scenarios, equipment typically operates continuously for 24 hours. The accuracy of installation directly determines the operational stability of the pumps, while the timeliness of routine maintenance affects both the service life of the equipment and the efficiency of water supply and drainage network operations. Based on the actual operating conditions of municipal engineering projects, we have systematically organized the key points for installation and subsequent maintenance into modular sections, ensuring practical applicability and alignment with the on-site operational requirements of water treatment plants, pressurized pumping stations, and drainage pumping stations.

　　I. Core Considerations for Installing Double-Suction Split-Casing Pumps (Focus on Key Control in Municipal Applications)

　　Municipal pump stations are typically designed with underground or semi-underground layouts. The pipeline connections are complex, and installation space is limited. Therefore, installation must carefully consider coaxial alignment, sealing performance, foundation load-bearing capacity, and compatibility of suction and discharge pipelines. It’s crucial to avoid issues such as vibration, leakage, and cavitation caused by installation deviations. Key steps should be meticulously controlled in a phased manner.

　　1. Basic installation: Lay a solid foundation and ensure compatibility with municipal heavy-duty operating conditions.

　　• The foundation shall be constructed using reinforced concrete according to the manufacturer’s drawings. Given the large flow rate of the municipal pump and its heavy equipment weight, the foundation’s load-bearing capacity must accommodate at least twice the total weight of the equipment to prevent settlement during long-term operation.

　　• The basic level error shall be ≤0.1 mm/m, the surface shall be smooth and free of hollow spots, and the deviation in position and verticality of the embedded anchor bolts shall be ≤2 mm. The grouting of the bolt pre-reserved holes must use high-strength, non-shrinking cement to ensure tightness.

　　• Install vibration-damping pads or dampers between the pump body and the foundation. Given the high noise-control requirements of municipal pump stations—especially those located near residential areas—vibration-damping devices must be matched to the equipment’s vibration frequency. Additionally, waterproofing treatment should be applied around the foundation (particularly for underground pump stations to prevent water accumulation).

　　2. Crew docking: Strictly control coaxiality to prevent operational vibration.

　　• The pump body and motor are connected via a coupling; coaxial alignment is critical: the radial deviation must be ≤0.05 mm, and the perpendicularity deviation of the end faces must be ≤0.02 mm/m. It is strictly prohibited to forcibly align the pipeline to correct the机组’s position, as this could cause deformation of the pump body and pump shaft.

　　• The coupling clearance must be reserved according to the model (typically 3–8 mm). Uneven clearance can cause the motor to overload. After installation, manually turn the shaft 3–5 revolutions; the unit is considered qualified if there is no jamming or unusual noise.

　　3. Installation of suction and discharge pipelines: A key factor in municipal water supply and drainage systems for preventing cavitation and leaks.

　　• Suction pipeline: It must be short, straight, and sufficiently large in diameter, with minimal bends and reducers. The nominal diameter should not be smaller than the pump’s inlet port diameter. The entire suction pipeline must be completely airtight (municipal water supply systems are strictly prohibited from drawing in air, which could cause flow interruption). All flanged connections must be fitted with sealing gaskets; when using metal gaskets, ensure they are flat and smooth; for rubber gaskets, make sure they are compatible with the medium’s temperature. At the suction pipe inlet, a foot valve or strainer must be installed (the strainer’s mesh size should be appropriate for the medium; for stormwater drainage systems, use a strainer designed to prevent debris from entering). The inlet should be positioned at least 1.5 times the diameter of the inlet port above the bottom or side walls of the reservoir to avoid cavitation and vortex formation.

　　• Pressure pipeline: Install check valves (to prevent water hammer caused by pump shutdown from impacting the municipal network; slow-closing check valves are preferred), gate valves or butterfly valves (for flow regulation), and flexible connectors (to absorb pump vibrations and prevent stress transmission through the pipeline). Valve installation locations should be easily accessible for operation and maintenance. The pressure pipeline must be equipped with a pressure gauge at the pump outlet and a vacuum gauge at the pump inlet, with measurement ranges 1.5 to 2 times the working pressure. At municipal pressurization pump stations, air vents should be installed at the highest points of the pipeline, and drain valves should be installed at the lowest points.

　　• After all piping has been installed, a hydrostatic test must be conducted. The test pressure for water supply pipelines shall be 1.5 times the working pressure; the pipeline shall be held at this pressure for 30 minutes, and it shall be considered qualified if there is no leakage and the pressure remains stable. Drainage pipelines shall undergo a sealing test in accordance with municipal drainage standards.

　　4. Electrical and Auxiliary Installation: Designed to meet municipal continuous-operation requirements

　　• The accompanying motor must comply with municipal power standards, have secure wiring connections, and be properly grounded (grounding resistance ≤ 4Ω). Pumps equipped with variable-frequency speed control must be paired with dedicated variable-frequency cables to prevent electromagnetic interference.

　　• Install a liquid-level controller (for automatic start-stop operation of municipal pump stations—for example, starting the pump at high water levels and stopping it at low water levels in rainwater tanks), as well as overload protection devices. All electrical components must be waterproof and dustproof (suitable for underground pump stations).

　　• The sealing water and cooling water pipelines of the pump body (for large double-suction pumps) must be properly connected to ensure that the water pressure and flow rate meet the requirements. In municipal environments with high temperatures, it is necessary to check the proper operation and unobstructed flow of the cooling system.

　　5. Trial Run: Must be performed after installation to eliminate potential hazards.

　　• Before starting the trial run, first fill and bleed the pump (the municipal water supply pump must be completely filled with water; dry running is strictly prohibited). Open the inlet valve and close the outlet valve. Then, check the oil level (the lubricant oil level in the bearing housing should be between 1/2 and 2/3 of the oil gauge—suitable for long-term municipal operation) and the sealing condition.

　　• Briefly jog the motor to check whether the rotation direction matches the pump body’s label (reversing the direction can result in no water discharge and damage to the pump shaft). After confirming the correct rotation direction, run the pump continuously for 2–4 hours.

　　• During the trial run, monitor the following key indicators: bearing temperature ≤ 75℃, motor temperature ≤ rated temperature rise, vibration level ≤ manufacturer’s specified value (typically ≤ 0.1 mm), stable inlet and outlet pressures with no leaks or unusual noises. For municipal drainage pumps, a overload test run is required; the pump is considered qualified if it can operate at short-term overloads (110% of rated flow) without any abnormalities.

[For more information on single-stage double-suction split-case pumps—including model specifications, parameters, selection guidelines, and quotation options—please click the image above to learn more.]

　　II. Double-suction mid-section pump Daily Maintenance and Upkeep (Practical Tips for Municipal Water Supply and Drainage)

　　Municipal double-suction, center-open pumps are primarily used as core equipment for water supply and drainage. Maintenance follows the principle of “prevention first, regular inspections, and timely replacement,” and is divided into three components: daily patrols, periodic maintenance, and predictive fault diagnosis. This approach caters to the varying maintenance needs of both unmanned pump stations and conventional pump stations in municipal engineering projects, with particular emphasis on managing three key areas: wear-prone parts, seals, and lubrication.

　　1. Routine inspections (for municipal pump stations, it is recommended to conduct inspections every 2-4 hours; for unmanned pump stations, remote monitoring is advised)

　　• Operating parameters: Real-time monitoring of inlet and outlet pressures, flow rates, motor current/voltage, and rotational speed. When pressure fluctuations occur in the municipal pipeline network, promptly adjust the frequency converter or valves to prevent the pump from operating for extended periods under low-efficiency or overloaded conditions.

　　• Temperature and Vibration: Use a thermometer to check the temperature of the bearing housing and motor casing, and use a vibration analyzer to monitor the vibration of the pump body and motor. If a sudden temperature rise or abnormal vibration is detected, immediately stop the machine for inspection.

　　• Sealing and Leaks: Check the pump body, flange connections, and shaft seals for any water leaks. Slight dripping at the shaft seal of municipal water pumps (packing seal or mechanical seal) is normal (10–20 drops per minute for packing seals). If the leakage exceeds the acceptable level, address it promptly. Under no circumstances should sealing components be removed under pressure.

　　• Lubrication and Cooling: Check that the bearing housing lubricant is free of emulsification and impurities, with the oil level at the proper level; ensure that the cooling water lines are unobstructed and the water pressure is stable; for large pumps, verify that the oil flow and oil temperature at the dilute-oil station are normal.

　　• Auxiliary equipment: Check that check valves and butterfly valves are free of jamming; ensure that level controllers and protective devices are sensitive and effective; and verify that the screens on municipal drainage pumps are free of blockages (clean debris promptly to prevent flow reduction).

　　2. Regular maintenance (weekly, monthly, quarterly, and annual maintenance, tailored to the city’s continuous operation requirements)

　　Weekly Maintenance (Simple Maintenance, Does Not Affect Operation)

　　• Clean dust and debris from the pump body and motor surfaces, and check whether the base bolts and coupling bolts are loose.

　　• Check the lubricant oil level; promptly top up with the same type of lubricant if the level is insufficient, and clean the oil dipstick and oil cup.

　　• Open the pipeline drain valve to remove accumulated water and impurities, and check whether the filter screen is clogged and clean it accordingly.

　　Monthly maintenance (in-depth inspection, short-term shutdown)

　　• Check the condition of the shaft seals: If the packing seal is severely worn, tighten the packing gland appropriately (but avoid over-tightening to prevent the sleeve from overheating); if the packing has aged, replace it in batches. For mechanical seals, if there’s leakage, check whether the moving ring and stationary ring are worn and whether the spring has lost its effectiveness.

　　• Check the coaxiality of the coupling; tighten any loose bolts promptly and replace damaged elastic pads.

　　• Check the motor’s insulation resistance (using a megohmmeter; the insulation resistance between the stator windings and ground should be ≥0.5 MΩ), and ensure proper waterproofing of electrical connection points.

　　• For municipal drainage pumps, focus on cleaning the suction pipe strainer and removing debris from the flow passages within the pump body to prevent blockages that could reduce efficiency.

　　Seasonal Maintenance (Comprehensive Inspection, Tailored to Municipal Seasonal Conditions)

　　• Replace the lubricant in the bearing housing (select the oil type according to the manufacturer’s recommendations, such as No. 32 or No. 46 mechanical oil). When replacing the oil, completely drain the old oil and use kerosene to clean the bearing housing and bearings. Inspect the bearings for pitting, wear, excessive clearance, or any damage; replace them immediately if any defects are found.

　　• Inspect the mid-section sealing gasket inside the pump body. If it is aged or damaged, replace it promptly and re-tighten the mid-section bolts (tighten them evenly in a diagonal sequence, ensuring the torque meets the manufacturer’s specifications).

　　• Inspect the impeller and pump casing for cavitation and wear (municipal stormwater often contains high sand content, leading to rapid wear). Minor cavitation can be repaired by grinding; severe cavitation requires replacement.

　　• Verify pressure gauges, vacuum gauges, and liquid-level controllers to ensure accurate monitoring; calibrate pressure protection devices at municipal pressurized pump stations.

　　Annual maintenance (major overhaul; municipal pump stations are recommended to be shut down for inspection—develop a pipeline scheduling plan in advance)

　　• Disassemble the pump body completely, inspect wear-prone components such as the impeller, pump shaft, bearings, seals, and wear rings. Replace any components that show wear, deformation, or corrosion. If the clearance between wear rings exceeds 0.5 mm, they must be reground and re-matched.

　　• Inspect the pump casing and pump body for cracks or porosity. For municipal water supply pumps, conduct a hydrostatic pressure test to ensure tightness.

　　• Inspect the motor, replace the bearings and grease, re-balance the rotor, and test all key performance indicators of the motor.

　　• Inspect and maintain the suction and discharge pipelines, replace aged sealing gaskets and flexible connectors, check the sealing surfaces and valve stems of check valves and butterfly valves, repair or replace damaged components, and apply anti-corrosion treatment to the pipelines.

　　• Conduct a comprehensive overhaul of the variable-frequency control cabinet and protective devices, replace aged wiring and components, re-adjust parameters, and adapt to the municipal water supply/drainage conditions.

　　3. Shutdown and Long-Term Storage Maintenance (for municipal pump station inspections and winter freeze protection)

　　• Short-term shutdown (≤7 days): Close the inlet and outlet valves, open the pump body vent valve and pipeline drain valve, and completely drain any accumulated water from the pump and pipelines (a critical measure for municipal winter freeze protection, preventing the pump body and pipelines from cracking due to freezing). Maintain the bearing housing oil level at the proper level, and manually turn the pump shaft once daily to prevent the shaft from seizing.

　　• Long-term storage (>30 days, e.g., municipal drainage pumps stored during non-rainy seasons): Drain all accumulated water from the pump and pipelines; apply rust-preventive oil to metal surfaces such as the pump shaft, impeller, and flow passages. Replace packing seals with new ones and lubricate them with grease; apply rust-preventive grease to the moving and stationary rings of mechanical seals. Perform moisture-proof treatment on the motor and cover it with a dustproof cover. Apply grease to anchor bolts and coupling bolts to prevent rust; regularly inspect the equipment condition and manually turn the pump shaft 2-3 revolutions each month.

　　III. Core Pitfalls to Avoid During Installation and Maintenance (Specifically for Municipal Water Supply and Drainage Systems)

　　1. During the installation of municipal pump stations, it is strictly prohibited to rely on the pump body itself to support the weight of pipelines. Separate pipeline supports and hangers must be provided; otherwise, the pump body may deform and cause sealing leaks.

　　2. Municipal water pumps must never be run dry. Pump priming and air venting must be carried out thoroughly; any air leaks in the suction piping can lead to cavitation, which can severely damage the impeller and pump shaft.

　　3. During maintenance, pressurized operations are strictly prohibited. In particular, when disassembling the mid-opening cover, seals, or flanges, you must first close the inlet and outlet valves and relieve the pressure inside the pump to prevent water from spraying and injuring personnel and to avoid pressure release in the pipeline network.

　　4. Since municipal stormwater drainage pumps handle media containing sand and debris, they cannot be maintained according to the standards applicable to water pumps. Therefore, it is necessary to increase the frequency of filter screen cleaning and flow path inspections to prevent wear and blockage.

　　5. Pumps operating with variable frequency drives should not be run continuously at low frequencies (<30 Hz), as this may cause motor overheating and pump body vibration. Flow regulation in municipal pipe networks should be achieved by combining valves with variable frequency drives to ensure that the pump operates within its efficient range.

　　6. For underground municipal pump stations, it is essential to ensure proper moisture protection and ventilation of equipment to prevent electrical components from becoming damp and short-circuiting, as well as to avoid condensation and corrosion on the pump body surface. Regularly inspect the pump station’s drainage system to prevent water accumulation from damaging the equipment.