Once the water pump of the cooling tower stops working, the entire heat dissipation chain will break. To transform "post-event repair" into "pre-event maintenance", just remember the five-character formula of "observe, measure, clean, moisten, and replace". Below, it will be broken down into four levels: daily, monthly, quarterly, and annual, all of which can be completed by one person.
I. Cooling Tower Pump:Daily Inspection (2 minutes)
Check the pressure: The pressure gauge at the pump outlet should be stable at ±0.02 MPa of the rated value. If the pointer shakes, it indicates that the impeller is cavitation or the inlet filter screen is clogged.
Listen to the sound: Normally, it is a uniform "buzzing". If there is metal friction, the machine will stop immediately. This is mostly due to insufficient oil in the bearing or the impeller rubbing against the casing.
Feel the motor: The temperature rise of the casing should be ≤ 40K (it feels slightly hot but can be touched continuously for 3 seconds). If the temperature exceeds the limit, first check if the fan cover is blocked by a plastic bag.
II. Cooling Tower Pump:Monthly Maintenance (30 minutes)
Clean the filter screen: Close the inlet and outlet valves, remove the Y-type filter, and rinse it in reverse with tap water. The visible light transmittance of the filter screen holes is less than 80% and it must be replaced.
Measuring current: Use a clamp meter to measure the three phases. If the deviation of any two phases is greater than 5%, it indicates that there is a short circuit between the turns of the coil or the voltage is unbalanced. An electrician is required to conduct a thorough inspection.
Lubricating the bearing: Fill 2/3 of the oil cup with new lithium-based grease (NLGI-2), and squeeze out the old grease from the oil drain hole until the color is uniform. Maintenance-free motors with sealed bearings can be skipped, but the operating time needs to be recorded and replaced as a whole after 8,000 hours.
III.Cooling Tower Pump: Quarterly Depth (1 hour)
Check the coupling: If the radial crack of the rubber block is greater than 2mm, replace it immediately. Recalibrate the coaxiality, with the radial deviation ≤ 0.1mm and the angular deviation ≤0.2°; otherwise, the bearing life will be halved.
Insulation measurement: 500 V megohmmeter. The stator to ground should be ≥20 MΩ. If it is lower than 5 MΩ, it needs to be dried or impregnated with paint.
Sealing inspection: The leakage of mechanical seals should be ≤5 drops per minute. If it exceeds the standard, replace the spare parts. When replacing, keep the roughness Ra of the bearing sleeve ≤0.8 μm; otherwise, the new seal will wear out and fail quickly.
IV. Cooling Tower Pump:Annual Overhaul (Half a day)
Disassemble the impeller: Pull it out with a puller and check if the front and rear cover plates have been ground into grooves like sandpaper. If the groove depth is greater than 1mm, it indicates that sand has entered the pump cavity and a 60-mesh cyclone desander needs to be installed.
Bearing replacement: Copy down the model of the old bearing (example 6204-2Z), purchase P5 grade of the same specification, heat to 90℃ and quickly install the shaft. Direct knocking is strictly prohibited.
Curve calculation: Record three points of "flow - head" at different opening degrees of the outlet valve and compare them with the factory curve. If the efficiency attenuation is greater than 10%, consider replacing the entire pump or cutting and modifying the impeller.
V.Cooling Tower Pump: Common Fault Quick Check Table
Sudden drop in flow: First, close the outlet valve slightly. The pressure rises → the filter screen is clogged. The pressure remains low → the impeller is worn or cavitation occurs.
Motor overload: The current exceeds the nameplate by 15%, mostly due to bearing jamming or low voltage from 380V to 340V.
Water hammer abnormal noise: The check valve has failed. Installing a micro-resistance slow-closing check valve can eliminate it.
VI. Cooling Tower Pump:Safety and Records
Before performing any maintenance, "double power-off" - turn the switch to OFF and lock it, then test the electricity. All the data are written into an A5 inspection sheet: pressure, current, insulation, and oil change time. For the next maintenance, compare the trends first to immediately see the rate of degradation.
By adhering to the "small steps and fast pace", the MTBF (Mean Time Between Failures) of the water pump can be increased from 2 years to 5 years, saving about 30% of the annual maintenance cost. It also keeps the cooling tower running at the "design point" all the time, and the electricity bill drops by 5% simultaneously - achieving multiple benefits at once.
