With the rise of artificial intelligence, cloud computing, and high-performance computing, data centers must manage ever-increasing thermal loads. To ensure the safety of high-density racks and improve the energy efficiency of facilities, liquid cooling has emerged as a key solution. However, this requires precise measurement and control of flow rates in each hydraulic loop. Fuji Electric’s s-flow ultrasonic flow meter provides a reliable, compact solution with no pressure drop to optimize the monitoring of liquid cooling circuits.
Data centers are at the heart of the digital transformation. The rise of AI, HPC, and cloud services is significantly increasing server power density. This trend requires operators to rethink their thermal architectures to prevent overheating, performance degradation, and service interruptions.
Liquid cooling—whether through direct-to-chip solutions, rear-door heat exchangers, or dedicated hydronic circuits—enables heat to be removed as close as possible to sensitive components. This approach offers more efficient heat transfer than air cooling and meets the needs of high-density racks.
However, this evolution brings with it new challenges. Data center operators must control flow rates, balance water loops between racks, quickly detect anomalies, and improve overall energy efficiency. The document also highlights the importance of ASHRAE guidelines for IT environments, PUE targets, and environmental commitments related to reducing water and energy consumption.
In a high-density data center, insufficient flow in a cooling loop can cause localized overheating of processors. This situation can lead to a drop in performance or even a critical service outage. Conversely, uncontrolled excess flow unnecessarily increases the pumps’ power consumption and reduces the facility’s energy efficiency.
The challenge becomes even greater in systems comprising dozens or hundreds of cooling loops. Without reliable flow measurement, it becomes difficult to identify hydraulic imbalance, heat exchanger fouling, the presence of air bubbles, or the onset of a leak.
For example, when adding new IA racks, a change in the hydraulic system can disrupt the entire network without being immediately detected. Operators therefore need a solution for measuring liquid cooling flow that is accurate, robust, and easily integrable with existing monitoring systems.
Fuji Electric's S-flow ultrasonic flowmeter is designed to meet the needs of liquid cooling systems in data centers. It uses time-of-flight ultrasonic measurement technology, which allows for the measurement of liquid flow without any moving mechanical parts.
This design offers a major advantage: it does not add any pressure drop to the circuit. The fluid flows freely, without any obstructions in the pipe, which helps maintain the system’s hydraulic efficiency. The compact, one-piece sensor also facilitates direct in-line integration, even in space-constrained technical environments such as high-density racks or loops located near racks.
The S-Flow measures low to medium flow rates with excellent repeatability, a critical feature for direct-to-chip cooling systems or rear-of-rack heat exchangers. Its analog and digital outputs enable easy integration into data center monitoring architectures, including BMS or SCADA systems. Real-time flow data enables adjustment of pump speeds, detection of deviations, and optimization of cooling distribution to closely match the actual needs of IT equipment.
Ensuring proper cooling for high-density racks
Accurate, continuous airflow measurement ensures that each rack receives the airflow necessary to maintain its thermal performance.
Optimizing the energy efficiency of hydronic systems
By preventing unnecessary over-flow, the flow meter helps reduce pump consumption and improve the overall efficiency of the data center.
Reduce maintenance costs
The technology, which has no moving parts, minimizes mechanical wear and reduces the risk of clogging associated with internal components.
Improving the availability of facilities
Early detection of deviations, anomalies, air bubbles, leaks, or drops in hydraulic performance allows for intervention before an incident compromises service continuity.
Easier integration into monitoring systems
Thanks to its analog and digital outputs, the s-flow flow meter integrates easily into existing BMS and SCADA systems.
Accurately measure flow rate without causing pressure loss
Transit-time ultrasonic technology ensures reliable measurement without obstructing the pipe.
Simplify installation in confined spaces
The compact, one-piece sensor allows for direct in-line integration, even when space is limited.
Compatible with high-density liquid cooling systems
The flow meter is compatible with water and water/glycol mixtures used in direct-to-chip cooling applications.
Improving the reliability and availability of facilities
Its design, which has no moving parts, minimizes mechanical wear and contributes to long-term operation.
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