Beyond stainless steel: A proven solution for data center liquid cooling

According to the Uptime Institute, cooling system failures account for approximately 14 percent of all data center outages: these incidents are incredibly costly and can lead to significant reputational and operational damage. Maximizing 24/7 data center uptime is therefore critical for businesses to maintain customer trust, maximize revenue, and guarantee data integrity.

When it comes to data center cooling, reliability, performance, and material durability are non-negotiable. As more operators shift to liquid cooling to manage increasing heat densities, maintaining fluid quality within the technological cooling system (TCS) remains a persistent challenge, particularly due to the impact of corrosion.

Corrosion introduces serious risks, such as costly damage to heat exchangers, coils, and piping, as well as critical failures in GPUs and CPUs if quick connectors or narrow flexible piping become clogged.

Furthermore, corrosion significantly compromises heat transfer efficiency, both in the heat exchangers of the CDU (between the chilled water system and the TCS) and in the cold plates clamped on CPUs and GPUs. If efficient heat transfer is not maintained, CPU and GPU temperatures may exceed junction temperatures, leading to severe performance degradation.

To mitigate these risks, several actions can be taken:

• Using a corrosion inhibitor medium such as a propylene glycol mixture (PG25 heat transfer fluid),
• Implementing effective fluid quality monitoring and management solutions, such as degassing technology or choosing appropriate filtering systems down to 25µm (crucial especially for the system’s secondary side),
• Selecting corrosion-resistant materials (i.e, stainless steel, coated metals, or IMI’s AMETAL brass alloys).

Let’s now explore the final – and critical – element: selecting the right materials to come into contact with the heat transfer fluid.

Rethinking metals: Is stainless steel the only option?

Not necessarily. While stainless steel is widely used for its reputation in durability, recent testing has revealed that specially engineered brass alloys can offer equally robust performance in data center HVAC cooling applications.

In collaboration with RISE Research Institutes of Sweden, IMI has conducted comprehensive corrosion testing comparing stainless steel grades 1.4301 (AISI 304) and 1.4305 (AISI 303) with IMI’s proprietary brass alloys (such as AMETAL CW709R, CC751S, CB751S).

The test conditions were designed in accordance with the ASHRAE and OCP-supported methodology ASTM D8040, using industry-standard propylene glycol-based heat transfer fluids (PG25-class HTFs), such as Dowfrost LC25 and Dynalene LC-PG.

To simulate a worst-case scenario, exposure tests were conducted at a standard temperature of 88°C, with added salts and continuous aeration. In parallel, a second test was commissioned to more closely replicate realistic cooling conditions: in this case, the HTFs were deaerated (closed system) and tested at a lower temperature of 4°C.

Results that speak for themselves

The results confirm that IMI’s proprietary AMETAL:

• Offers excellent compatibility with PG25-class HTFs, one of the most used and recommended heat transfer fluids for data centers;
• Demonstrate uniform corrosion rates of less than 8 μm/year at 88 °C and under 3 μm/year at 4°C in diluted PG25-class HTF
• Met or exceeded the ASTM D8040 requirements, aligned with the ASHRAE and OCP-defined corrosion limits:
  • ≤ 0.46 mpy (approximately 11.7 µm/year) for brass
• Provide a viable alternative to stainless steel.

More than just a metal

This isn’t just a material upgrade, it’s a system-wide advantage. By choosing IMI’s proprietary AMETAL, developed and patented in the 1960s and refined through its third-generation release in the 1990s, you ensure exceptional compatibility with propylene glycol-based heat transfer fluids as well as with water. This means accessing a fully validated, high-performance solution designed to support demanding cooling loops without compromising system longevity or reliability.

With over one million AMETAL valves operating in demanding HVAC environments (including PG25 systems and cold climates) and thousands of them successfully deployed in hyperscale and enterprise data centers across Singapore, the USA, France, Spain, and Italy, IMI helps ensure cooling systems are:

• Reliable;
• Efficient;
• Fully compliant with leading industry standards.

Precision control and optimized efficiency

IMI TA’s balancing and control valves, essential for accurate temperature regulation, are built using AMETAL to withstand harsh fluid environments while enabling optimal system performance:

• TA-Smart (DN15–50)
  A next-generation smart control valve with measurement capabilities, providing seamless installation, commissioning, and best-in-class control performance, which can lead to energy savings. TA-Smart offers accuracy and transparency and is now confirmed to be compatible with ASHRAE and OCP requirements thanks to its AMETAL construction.
• TA-Modulator (DN10–50)
  A pressure-independent balancing and control valve (PIBCV) is a 3-in-1 product that combines the functionality of a balancing valve, control valve, and DP controller. It offers precise EQM flow characteristics that can lead to unparalleled controllability, energy efficiency, and resilience.
• STAD (DN10–50)
  The world’s most installed balancing valve, the STAD, is renowned for its accuracy, compactness, and durability, with the added confidence of AMETAL’s corrosion resistance for the higher standards of modern data center environments.

These components support high control accuracy, optimized energy use, and greater longevity in liquid-cooled data center systems.

Protection for your investment

In addition to flow control, air separation and degassing play a crucial role in reducing corrosion and supporting system reliability. IMI Pneumatex’s Simply Vento degasser brings together compact design, efficient air removal, and smart connectivity, all housed in a body made from the corrosion-resistant AMETAL alloy.

By removing dissolved gases that can lead to corrosion and performance degradation, Simply Vento further enhances the resilience of data center HVAC systems, now validated for aggressive HTF environments.

IMI sustainability commitment

Navigating sustainability standards is essential for data centers as they face growing pressure to reduce energy consumption and emissions, not only to align with UN Sustainable Development Goals 7 (Affordable and Clean Energy) and 13 (Climate Action), but also to comply with the updated EU Energy Efficiency Directive (EED), which imposes stricter requirements on data center operations. In the United States, compliance with the Federal Energy Management Program (FEMP) is also a key consideration for the industry.

At IMI, sustainability is a key pillar of our product development strategy, and AMETAL is no exception. Our AMETAL variants are made using 90–100 percent recycled brass alloys and manufactured in Sweden, where we benefit from renewable energy sources and an integrated on-site recycling loop that returns brass scrap directly into the production cycle. This circular approach contributes to a substantial reduction in product-level CO₂ emissions.

Compared to competitors offering similar products, our use of high-recycled-content materials and green electricity gives us a measurable edge in reducing environmental impact, all without compromising performance or durability in demanding data center environments:

It’s important to note that, in addition to the data shown above, our EPDs have also been independently third-party verified.

Looking ahead

As data center infrastructure and regulations evolve, so must the technologies that support it. IMI’s investment in materials science and fluid compatibility testing is a clear demonstration of its commitment to future-proofing HVAC systems.

Our team offers comprehensive support for designing customised HVAC systems, whether for new constructions, prefabricated modules, or retrofit projects. 

To learn more about our test results or to explore how our solutions can support your cooling strategy, get in touch with our team here.