Cooling Tower Maintenance Guide

Cooling towers, as key equipment for heat exchange in thermal systems, are widely used in air conditioning, refrigeration, industrial production, and other fields. Their operational efficiency directly affects the energy consumption and stability of the entire system, while scientific and standardized maintenance is the core to ensuring long-term efficient operation of cooling towers. This article constructs a complete cooling tower maintenance system from four dimensions: basic understanding of maintenance, maintenance key points in different cycles, common fault handling, and maintenance safety specifications, helping equipment managers systematically master maintenance techniques and extend equipment service life.

I. Basic Understanding and Cycle Planning of Cooling Tower Maintenance

(1) Core Value of Maintenance

Cooling towers achieve heat dissipation through heat exchange between water and air. During long-term operation, they are susceptible to factors such as water quality, environmental dust, and microbial reproduction. Data shows that the heat exchange efficiency of cooling towers without systematic maintenance may decrease by 10%-15% annually, energy consumption increases by about 20%, and equipment failure or shutdown is more likely due to component corrosion and scaling. Standardized maintenance can not only maintain more than 95% of the equipment's designed efficiency but also extend the equipment life by 3-5 years, significantly reducing the full life cycle cost.

(2) Scientific Maintenance Cycle Division

According to the equipment operation characteristics, maintenance cycles are divided into four levels: daily/weekly patrol inspection, monthly maintenance, quarterly in-depth maintenance, and annual overhaul. Daily patrol inspection focuses on operational status monitoring; monthly maintenance focuses on cleaning and basic component inspection; quarterly maintenance requires systematic functional testing; annual overhaul involves disassembly and inspection of core components. This layered maintenance system enables early detection and resolution of issues.

II. Operation Specifications for Daily Patrol Inspection and Monthly Maintenance

(1) Key Points of Daily/Weekly Patrol Inspection

Patrol inspection should focus on three core indicators: First, observe the dashboard to ensure that the fan current and operating voltage are within ±5% of the rated value—abnormal fluctuations may indicate abnormal motor load. Second, check whether the water distribution system is uniform; if local water splashing or flow interruption is found, immediately inspect whether the nozzle is blocked or the water distribution pipe is damaged. Finally, monitor the water level in the collection pond, maintaining it within the 1/2-2/3 scale range of the water level gauge. Too low a water level can cause the water pump to run dry, while too high a level may cause water overflow.

(2) Implementation Steps for Monthly Maintenance

1.Filler Cleaning Operation: 

The cooling tower fill is the core area for heat exchange. It needs to be flushed from bottom to top with a high-pressure water gun (pressure controlled at 0.3-0.5MPa) monthly to remove deposited algae and sediment. If aging and fragmentation of the packing (with a damage rate exceeding 10%) are found, replace it in a timely manner to avoid affecting water flow distribution.https://www.chardonlabs.com/resources/cooling-tower-cleaning-and-maintenance/

2.Fan System Inspection:

 Focus on checking the gap between the fan blades and the air duct (maintaining a uniform distance of 5-8mm), and the angle deviation of the blades should not exceed ± 1 °, which can be calibrated one by one with an angle ruler. At the same time, tighten the anchor bolts of the motor, measure the temperature rise of the bearing (the temperature rise during operation should not exceed 40 ℃), and promptly replenish lithium based grease (approximately 50-100g per motor).

https://www.sciencedirect.com/science/article/abs/pii/S0378778822007563

3.Preliminary Water Quality Treatment: 

Detect the pH value of the water in the collection pond (which should be controlled at 6.5-8.5). If the pH value is lower than 6, add sodium hydroxide for adjustment; if it is higher than 8.5, put in sodium bisulfate. Meanwhile, add a broad-spectrum bactericide and algaecide at a dose of 50-100g per ton of water to inhibit microbial reproduction.

III. Technical Key Points for Quarterly In-depth Maintenance and Annual Overhaul

(1) Quarterly Systematic Maintenance

1.Spray System Overhaul:

 Disassemble the water distributor (for turntable-type water distributors, check the wear condition of the rotating bearing—if the radial clearance of the bearing exceeds 0.5mm, it needs to be replaced), and clean the scaling on the inner wall of the water distribution pipe (which can be soaked in a 5% citric acid solution for 2-3 hours and then rinsed). For tubular water distribution systems, dredge the nozzles one by one (the aperture should not be less than 80% of the design value), and use special dredging tools if necessary.

2.Special Maintenance for Reducer: 

Open the reducer end cover, check the gear meshing condition (the tooth surface wear depth should not exceed 15% of the tooth thickness), and replace the gear oil (it is recommended to use industrial gear oil with a viscosity grade of ISO VG 220, and clean the oil tank with kerosene when changing the oil). Meanwhile, calibrate the belt tension—press the middle of the belt with your finger, and the sinking amount should be within the range of 15-20mm.

3.In-depth Water Quality Detection: 

Send water samples to a professional laboratory for testing of calcium and magnesium ion concentration (which should be controlled below 400mg/L), turbidity (<5NTU), and conductivity (<1000μS/cm). According to the detection results, if there is an obvious scaling tendency, reverse osmosis pretreatment or add organic phosphonate scale inhibitors (with a dosing concentration of 10-20ppm) can be adopted.

(2) Core Projects of Annual Overhaul

1.Overall Packing Replacement: 

For cooling towers that have been in use for more than 5 years, it is recommended to replace the packing as a whole (the aging and embrittlement threshold of PVC material packing is about 5 years). When replacing, pay attention to the installation flatness of the packing layer (the error ≤5mm/㎡) and the load-bearing capacity test of the interlayer support beams (the load-bearing capacity per square meter is not less than 80kg).

2.Anti-corrosion Treatment of Metal Structures: 

Carry out sandblasting and rust removal on the tower body steel structure (reaching the Sa2.5 grade standard), and apply epoxy zinc-rich primer (dry film thickness 80-100μm) and acrylic polyurethane topcoat (dry film thickness 100-120μm), especially paying attention to the strengthened treatment of easily corroded parts such as welds and bolt connections.

3.Comprehensive Overhaul of Water Pumps:

 Disassemble the water pump impeller (replace it if the wear depth exceeds 2mm), detect the roundness of the shaft diameter (the error ≤0.05mm), and replace the mechanical seal (the leakage amount should be <5ml/h). Carry out insulation testing on the motor (the insulation resistance of the stator winding ≥10MΩ), and rewind the winding if necessary.https://www.sciencedirect.com/science/article/pii/S2212827123000185

IV. Common Fault Diagnosis and Maintenance Safety Specifications

(1) Typical Fault Handling Procedures

1.Abnormal Fan Vibration: 

First, check the blade dynamic balance (the weight deviation of a single blade ≤5g), then check the bearing clearance (replace the deep groove ball bearing if the radial clearance exceeds 0.15mm), and finally detect the motor rotor eccentricity (the allowable value ≤0.03mm).

2.Decreased Cooling Efficiency: 

If there is no obvious blockage in the packing, check the fan air volume (which should reach more than 90% of the design value), which can be measured with an anemometer at the center of the air outlet (the wind speed should be ≥4m/s). Meanwhile, calculate the circulating water volume (the error ≤±10%), and adjust the water pump frequency or replace the impeller if necessary.

(2) Safety Guidelines for Maintenance Operations

1.High-altitude Operation Protection:

 When climbing the cooling tower platform, a double-hook safety belt (with a load-bearing capacity ≥150kg) must be used. The edge of the operation platform should be equipped with a protective railing with a height ≥1.2m, and a safety net (with a mesh size ≤10cm×10cm) should be set below.

2.Electrical Safety Specifications: 

For all live operations, cut off the main power supply of the equipment and hang a "No Closing" warning sign, and use insulated tools (with an insulation resistance ≥100MΩ). When operating in a humid environment, lay an insulating rubber mat (with a voltage resistance level ≥10kV).

3.Chemical Reagent Management: 

A separate warehouse (with good ventilation and a temperature ≤30℃) should be set up for storing chemical agents such as bactericides and algaecides. Operators should wear acid and alkali-resistant gloves (made of nitrile rubber) and goggles. In case of reagent leakage, immediately neutralize it with lime (for acid agents) or rinse it with clean water (for alkali agents).

V. Maintenance Differences for Different Types of Cooling Towers

(1) Targeted Maintenance for Open and Closed Cooling Towers

1.Open cooling towers: 

Due to the direct contact between the water circulation system and air, key attention should be paid to the accumulation of biological slime in the packing. It is recommended to add a non-oxidizing biocide shock treatment once a quarter (with a dosage twice the conventional amount), and strengthen the daily cleaning of the collection pond filter (aperture ≤2mm).

2.Closed cooling towers:

The core lies in the scaling control of heat exchange coils. In addition to routine water quality detection, an eddy current flaw detector should be used annually to detect the wall thickness of the coils (replacement is required when the corrosion allowance ≤0.5mm), and pulse water flushing (pressure 1.5-2MPa) should be adopted to remove deposited impurities inside the pipes.

(2) Differentiated Maintenance for Industrial and Civil Cooling Towers

1.Industrial cooling towers (such as hyperbolic towers in power plants):

Crack detection of the concrete structure of the air duct should be carried out every six months (epoxy resin grouting repair is adopted when the crack width >0.2mm), and the water distribution density should be monitored (it is advisable to control it at 5-15t/(㎡·h)) to avoid excessive aging of local packing caused by uneven load.

2.Civil central air conditioning cooling towers: 

Focus on noise control maintenance. Check the fan shock pads every quarter (compression deformation ≤10%), replace the aging soundproof cotton (update when the sound absorption coefficient decreases ≥30%), and ensure the operating noise ≤55dB(A).

VI. Environmental Protection and Energy Saving Optimization Measures

(1) Water Resource Recycling Technology

1.Replace traditional cooling towers with evaporative condensers, which can reduce water consumption by more than 90%. Meanwhile, a condensate recovery system (recovery rate ≥85%) is equipped to be used for flushing packing or supplementing circulating water.

2.Install an intelligent water replenishment valve (response time ≤5 seconds), which dynamically adjusts the water replenishment amount according to the water level in the collection pond and the evaporation amount to avoid excessive loss of traditional float valve water replenishment (water saving of 10-15% can be achieved).

(2) Environmental Protection Discharge Control Requirements

1.The discharged wastewater must meet the third-level standard of the Comprehensive Wastewater Discharge Standard (GB8978-1996), with key control of indicators such as COD (≤500mg/L) and ammonia nitrogen (≤35mg/L). When exceeding the standard, an emergency treatment pond (volume ≥1.5 times the daily discharge) must be started;

2.The fan blades adopt low-VOCs coatings (volatile organic compound content ≤100g/L), and the waste lubricating grease during maintenance must be handled by a qualified unit (hazardous waste code HW08), and random dumping is prohibited.

VII.Emergency Response Plan for Malfunctions

(1) Process for handling sudden water leakage accidents

1.Immediately shut down the circulating water pump and makeup valve, and start the backup cooling tower (switching time ≤ 15 minutes);

2.Temporary repair of cracks using polymer rapid sealing adhesive (curing time ≤ 5 minutes). For pipeline damage with a diameter ≥ 50mm, a pressurized sealing fixture (pressure resistance ≥ 1.0MPa) is required;

3.Afterwards, a pressure test should be conducted on the leaking area (with a test pressure of 1.5 times the working pressure and no leakage for 30 minutes), and the cause of the leakage (such as corrosion/vibration fatigue) should be analyzed to develop targeted preventive measures.

(2)Fire prevention and emergency response

1.Flammable materials are prohibited from being stacked within 5 meters around the cooling tower. An automatic sprinkler fire extinguishing system (nozzle spacing ≤ 3m) and dry powder fire extinguishers (no less than 2 per 50 square meters) should be installed;

2.If there is a burning of the filling material, the fire water cannon (flow rate ≥ 30L/s) should be immediately activated to cover and extinguish the fire, and personnel within a 20 meter radius should be evacuated. Afterwards, the filling material in the burning area and adjacent layers should be completely replaced to prevent hidden combustion.