Flow measurement of coolants in a turn-key data center

A French EPC designs and builds turnkey data centers for hyperscalers, colocation providers and enterprise clients in France and worldwide. Their activities include secure, resilient infrastructure (power redundancy, cooling, continuity of service) to support high‑density computing and mission‑critical workloads. The group is committed to “green IT” and energy‑efficient operations, supporting initiatives such as ISO‑certified energy management that reduce power and cooling consumption.

For a recently built data center with an IT power capacity of 20 MW in the first phase, the EPC contractor required suitable flow measurement instrumentation to monitor the cooling of the IT equipment. The data center was equipped with several pipes ranging from 2" (~DN50) bis 16" (~DN400), circulating a water-glycol mixture from the chillers to the server room CRAC units or CDUs. The water, mixed with ethylene glycol (EG) or propylene glycol (PG), serves as an excellent heat-transfer medium to protect the equipment from overheating.

The flowmeters were intended not only for process control but also to optimise power usage effectiveness (PUE), which must be monitored as a key technical indicator relating the total energy consumption of a data center to the energy used by its IT infrastructure. In addition to efficiency, the availability of cooling was a major focus. Redundant flow measurement and the correct choice of equipment were key factors in achieving this. This required tried-and-tested flowmeters with a solid installed base, designed to maintain high plant uptime and comply with industry standards. Due to the confined installation spaces, the meters needed to operate accurately with minimal or very short straight inlet runs.

To recover waste heat from the data centre and use it sustainably in the district heating network, the engineering company also required flowmeters approved for custody transfer. It was essential that these meters be certified in accordance with the European Measuring Instruments Directive (MID MI 004) for use in heat metering applications.

Based on experience gained from previous projects, the customer selected KROHNE as the preferred flowmeter supplier. With its broad portfolio of flow instrumentation and measurement technologies, KROHNE was able to provide a range of flow instruments that fully met the customer’s requirements in terms of technical performance, installation constraints, measurement quality, and sustainability targets, including carbon-footprint considerations.

Different electromagnetic flowmeters (EMFs) were assigned according to specific process functions. OPTIFLUX 4100 flowmeters are used in the coolant supply lines of the cooling loops for the servers, ensuring high accuracy and low pressure loss in the cooling distribution network. OPTIFLUX 2300 EMFs are installed in a redundant setup to control the cooling towers located on the roof, where a robust design, high accuracy, and high ingress protection rating are essential for reliable operation in outdoor environmental conditions.

Certified OPTIFLUX 4300 EMFs are used for the transfer of waste heat to the district heating grid in accordance with MID MI-004. Non-conductive media are measured using OPTISONIC 6300 ultrasonic clamp-on flowmeters, which enable non-intrusive flow measurement of non-conductive liquids without process interruption.

The wide range of flowmeters and flow technologies enables long term stable measurements in various applications – both with conductive cooling media and non conductive heat transfer fluids. The different measuring instruments take into account the large measurement ranges that are typically required in cooling networks and heat exchanger pipelines in data centres.

The rugged industrial design of the flowmeters allows installation in outdoor areas exposed to varying weather conditions, including temperature fluctuations, precipitation, and sunlight. For confined spaces, industry-standard meters are available that require little to no straight inlet and outlet runs.

In addition, KROHNE flowmeters are equipped with advanced diagnostic capabilities that continuously monitor instrument integrity and measurement performance, including sensor condition and signal quality. This enables on-site verification, supports predictive maintenance, and helps maintain extremely high plant availability – a critical requirement for data center operation.