Material Selection Guide for Closed Cooling Towers for Air Compressor Cooling
Jun 01, 2026
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As essential cooling equipment for screw air compressors and centrifugal air compressors, closed cooling towers adopt a closed circulating cooling liquid system, which is different from open cooling towers.
They can directly cool the lubricating oil and intake air of air compressors, and prevent impurities in water from entering the air compressor unit. This ensures long-term stable operation of the equipment.
The material of components directly determines the service life, heat exchange efficiency and later maintenance cost of cooling towers.
Combined with the operating characteristics of air compressors including high operating temperature, 24-hour uninterrupted continuous operation and uneven water quality of industrial circulating water, this paper conducts a comprehensive material selection analysis for four core components of closed cooling towers: heat exchange coils, tower shell, packing and spray pipelines, to match working conditions of different factory areas.
1. Core Heat Exchange Coil (Core Component Determining Cooling Efficiency)
The coil is the core component of a closed cooling tower. High-temperature hydraulic oil of the air compressor circulates inside the coil, while spray water outside realizes heat dissipation.
The coil bears long-term high temperature difference and water corrosion, making it the most critical part for material selection.
304 stainless steel coil is the first choice for ordinary inland factories with tap water circulation and non-corrosive water vapor environments. Featuring optimal cost performance, this material resists corrosion of conventional circulating water and avoids rusting and scaling easily. With moderate thermal conductivity, it fully meets the cooling demand for high-temperature medium of air compressors ranging from 70℃ to 95℃. It is also the standard configuration for closed cooling towers matched with air compressors in the market, with a normal service life of 8 to 10 years.
316L stainless steel coil must be adopted for coastal factories, chemical workshops, sites with underground water containing high chloride ions and environments with highly corrosive water mist. Compared with 304 stainless steel, 316L stainless steel has greatly improved resistance to chloride ion pitting corrosion, salt spray and acid-base corrosion. It can prevent coil perforation and water leakage as well as oil-water mixing that may damage the main unit of air compressors, making it suitable for harsh industrial environments.
T2 red copper coil is applicable for cooling with pure water, scenarios requiring extreme cooling efficiency and projects with sufficient budget. Red copper has a much higher thermal conductivity than stainless steel, improving the cooling efficiency by about 15% and accelerating heat dissipation. However, it has obvious shortcomings including poor corrosion resistance, easy scaling and corrosion in hard water and high-chloride water environments, as well as high cost. It is only commonly matched with high-end oil-free air compressors.
Ordinary carbon steel galvanized coils are not recommended. Despite their low price, they have poor resistance to high temperature and corrosion.
Tube wall rust and blockage will occur within half a year to one year, which easily causes high oil temperature alarm of air compressors and increases the risk of equipment shutdown and maintenance.
2. Tower Shell Material
Hot-dip galvanized steel plate shell is a universal option for indoor workshops. It features high hardness, good mechanical strength and strong impact resistance, adapting to heavy-duty workshop environments with the highest cost performance.
For outdoor installation, aluminum-magnesium-zinc coated steel plate shell is preferred, which can resist wind, rain and ultraviolet radiation without rusting permanently, doubling the outdoor service life.
Fiberglass reinforced plastic (FRP) shell is optional for humid and corrosive workshops with overall anti-corrosion performance and maintenance-free advantages.
Nevertheless, metal steel plates have higher structural strength, so metal shells are prioritized for large-scale cooling towers supporting air compressors.
3. Material of Packing and Spray Pipeline
Packing is used to disperse spray water and expand the heat exchange area. Virgin PVC oblique corrugated packing is adopted uniformly, with a temperature resistance up to 65℃.
It will not deform or age under conventional spray water temperature of air compressors. Recycled packing is strictly prohibited to prevent high-temperature collapse and water pipeline blockage.
Spray pipelines and nozzles are made of ABS engineering plastic with excellent anti-corrosion performance, no rust and uniform water output. Hot-dip galvanized steel pipes are adopted for conventional external circulating pipelines, while 304 stainless steel pipes are used for clean circulating systems.
4. Concise Material Selection Summary for Different Working Conditions
Ordinary inland factories: 304 stainless steel coil + galvanized steel plate shell + PVC packing, covering most air compressor applications with excellent cost performance;
Coastal and chemical corrosive factories: 316L stainless steel coil + aluminum-magnesium-zinc coated steel plate shell for long-term anti-corrosion performance;
High-standard cooling requirements: red copper coil to maximize cooling efficiency.
In conclusion, low-cost material selection blindly shall be avoided for closed cooling towers for air compressors. Coil corrosion and water leakage will directly cause failure of air compressor lubricating oil and even main unit locking.
Matching proper materials according to local water quality and factory environment can effectively reduce later maintenance and shutdown costs, and guarantee year-round continuous and stable operation of air compressors.
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