How to Choose the Right Coil Material for Your Closed-Circuit Cooling Tower

Emily Green

Emily is a senior R & D engineer at Oasis Bingfeng Fluid Equipment Co., Ltd. With over 10 years of experience in the cooling equipment industry, she has played a key role in the development of the company's core products, including closed cooling towers and air coolers.

The coil is where heat transfer happens in a closed-circuit cooling tower. The process fluid circulates inside the coil, while spray water flows over the outside, removing heat through evaporation.

Because the coil is in constant contact with both the process fluid and the external spray water, material selection directly affects service life, maintenance cost, and system reliability.

There is no single "best" material. The right choice depends on your specific operating environment.

Copper Coils

Copper offers the highest thermal conductivity among common coil materials. This means a copper coil can achieve the required cooling capacity with a smaller surface area, resulting in a more compact tower design.

When to choose copper:

Clean water or glycol-water systems

HVAC and data center applications

Environments free of ammonia and sulfur compounds

When maximum heat transfer efficiency is a priority

When to avoid copper:

Near fertilizer plants or refrigeration systems (ammonia risk)

Near power plants or refineries (sulfur compounds)

Coastal areas with salt mist exposure

Copper is an excellent material, but it is selective. If your environment contains ammonia or sulfur, copper will corrode quickly regardless of wall thickness.

Stainless Steel Coils

Stainless steel, particularly Grade 316, has become the standard choice for demanding industrial applications.

When to choose stainless steel:

Chemical processing plants

Coastal or high-humidity environments

High-chloride water conditions

Food, pharmaceutical, and clean-process applications

When long service life is a priority

Grade selection matters:

304: Suitable for general industrial use with mild water quality

316: Recommended for coastal areas, high-chloride water, and chemical environments

Stainless steel has lower thermal conductivity than copper, so the coil surface area needs to be larger to achieve the same cooling capacity. This is a fair trade-off for the significantly improved corrosion resistance.

Galvanized Steel Coils

Galvanized steel coils are zinc-coated carbon steel tubes that offer a cost-effective solution for less demanding applications.

When to choose galvanized steel:

Light industrial applications with clean water

Temporary or short-term installations

Budget-constrained projects in mild environments

Non-critical cooling applications

When to avoid galvanized steel:

Coastal areas

Chemical plants

Acidic or alkaline water conditions

Applications requiring 15+ years of service life

The zinc coating provides limited protection. Once compromised, the underlying carbon steel corrodes rapidly. Galvanized steel coils typically last 5-10 years in industrial conditions, compared to 15-20+ years for stainless steel.

Decision Framework

Use this simple framework to guide your selection:

Key Takeaway

Do not select coil material based on price alone. A cheaper coil that fails after 5 years costs far more than a properly specified coil that lasts 20 years.

Consider your environment, your process fluid, and your expected service life. When in doubt, stainless steel 316 is the safest choice for most industrial applications.

Need help selecting the right coil material for your application? Share your operating conditions with our engineering team, and we will recommend the optimal material for your closed-circuit cooling tower.