How to maintain and service sewage pumps

As an important equipment for treating sewage and wastewater, the maintenance and upkeep of sewage pumps directly affect their operational efficiency, service life and safety. The following is a detailed guide for the maintenance and care of sewage pumps, covering daily inspections, regular maintenance, fault prevention, and safe operation, etc.

I. Daily Inspection and Maintenance

Operation status monitoring

Sound and Vibration: During operation, listen for any abnormal noises from the pump body (such as metal friction sounds or impact sounds), and check if the vibration is uniform. Abnormalities may indicate impeller wear, bearing damage or foreign objects in the pump body.

Current and voltage: Use an ammeter to monitor the motor current. If it exceeds the rated value by more than 10%, it may be due to impeller blockage or motor failure causing overload.

Flow and pressure: Observe whether the flow at the outlet is stable and whether the pressure gauge reading is within the normal range. A sudden drop in flow rate may be due to a clogged inlet or worn impeller.

Sealing performance inspection

Mechanical seal: Check if there is any leakage at the sealing point. Minor leakage can be solved by adjusting the spring pressure or replacing the sealing part. Severe leakage requires shutdown for maintenance.

Shaft seal: If packing seal is adopted, regularly adjust the gland bolts to maintain a small amount of water dripping (about 10-20 drops per minute) for lubrication and cooling.

Liquid level and Medium

Liquid level control: Ensure that the pump operates above the low liquid level to prevent seal damage or motor burnout caused by idling.

Medium characteristics: Check the content of solid particles and fibrous substances in the sewage. If it exceeds the pump's passing capacity, a grille or filter needs to be installed.

Ii. Regular maintenance projects

Lubrication and maintenance

Bearing lubrication: According to the pump type (such as rolling bearings or sliding bearings), add grease or lubricating oil regularly as required by the manual. For instance, lithium-based grease should be replenished for rolling bearings every 2,000 hours of operation.

Motor bearings: Check the temperature of the motor bearings. If it exceeds 80℃, stop the machine for inspection and replenish the lubricating grease.

Replacement of vulnerable parts

Impeller: Check the wear condition of the impeller every six months. If the clearance of the wear ring exceeds the standard value (usually 0.5-1mm), the impeller or wear ring needs to be replaced.

Mechanical seal: Replace the mechanical seal once a year. If the medium is highly corrosive, the replacement cycle should be shortened.

Cable: Check if the outer sheath of the cable is damaged and if the joints are loose to avoid the risk of electric leakage.

Pump body cleaning

Internal cleaning: Disassemble the pump body every quarter to remove silt and debris from the impeller and pump casing to prevent blockage and corrosion.

Cooling water system: If the pump is water-cooled, check whether the cooling water pipes are unobstructed and whether the water pressure is stable.

Electrical system inspection

Grounding protection: Ensure that the grounding wire of the motor is firmly connected and the grounding resistance is ≤4Ω.

Insulation test: Use a megohmmeter to measure the insulation resistance of the motor winding to ground. If it is lower than 0.5MΩ, the motor needs to be dried or replaced.

Iii. Seasonal Maintenance

Winter protection

Anti-freezing measures: Drain the accumulated water in the pump when it is not in use to prevent the pump body from cracking due to freezing. If the ambient temperature is below 0℃, antifreeze should be added or the pump body should be kept running at a low temperature.

Insulation treatment: Wrap the pipes and pump bodies exposed outdoors with insulation materials to reduce heat loss.

Summer protection

Heat dissipation management: Clean the dust on the motor heat sink to ensure good ventilation. If the ambient temperature is too high, a forced ventilation device can be installed.

Moisture-proof treatment: Check the sealing of the control cabinet to prevent moist air from entering and causing short circuits in electrical components.

Iv. Fault Prevention and Handling

Common Faults and Solutions

The pump doesn't discharge water

Check whether the inlet valve is open and whether the impeller is clogged.

Confirm whether the motor rotation direction is correct (reverse rotation will cause no flow).

Insufficient traffic

Clean the inlet filter and adjust the gap between the impeller and the pump casing.

Check if the voltage is stable to avoid a decrease in rotational speed due to low voltage.

Motor overheating

Check whether the load is too heavy and whether the bearings are short of oil.

Confirm whether the ventilation openings are blocked and whether the ambient temperature is too high.

Seal leakage

Tighten the sealing cover bolts and replace the worn sealing parts.

If the leakage is caused by a bent shaft, it needs to be straightened or the shaft replaced.

Emergency response procedure

When severe leakage, abnormal vibration or motor smoke is detected, press the emergency stop button immediately.

Close the inlet and outlet valves, cut off the power supply, and hang the "Do Not Close" warning sign.

Record the fault phenomenon and contact professional maintenance personnel to investigate the cause.

V. Safety Operation Specifications

Personal protection

When maintaining, wear protective gloves and goggles to prevent sewage from splashing into the eyes or skin from coming into contact with corrosive media.

When working in a damp environment, use insulated tools and wear insulated shoes.

Operation taboos

It is strictly prohibited to disassemble the pipeline or clean the impeller when the pump is in operation.

Avoid striking the pump body with hard objects to prevent deformation or damage to the seal.

Do not change the motor wiring method at will to prevent reverse rotation or overload.

Vi. Long-term Maintenance out of Service

Pretreatment before deactivation

Drain the accumulated water in the pump and rinse the pump body and pipes with clean water.

Apply anti-rust oil to the metal parts to prevent rusting.

Start regularly

Run the machine no-load for 10 to 15 minutes every month to prevent the bearings from rusting and the motor from getting damp.

After operation, check the sealing performance to ensure there is no leakage.

Vii. Maintenance of Records and Archive Management

Establish a maintenance ledger

Record the time, content, replaced parts and maintenance personnel information of each maintenance.

Save data such as motor insulation tests and bearing temperature monitoring to facilitate the analysis of equipment status trends.

Spare parts management

Based on historical fault data, stock up on commonly used vulnerable parts (such as impellers, seals, and bearings).

Regularly check the spare parts inventory to avoid expiration or damage.