Clamp-on flow measurement in data centers

An internet giant operates global data centers to run its search, advertising, video, email, mapping, cloud, and AI services, processing and storing user and enterprise data while delivering low latency, scalable computing worldwide. The company also operates several data centers in the Philippines.

Safe and reliable operation of these data centers hinges on the efficiency of the cooling system, which utilises chillers together with computer room air conditioners (CRACs) or coolant distribution units (CDUs). To directly dissipate heat from the server racks, the company operates cooling loops at different sites with a mixture of water and ethylene glycol (EG) or propylene glycol (PG) as the coolant.

To continuously monitor the coolant flow to the server rooms, the internet provider previously relied on paddlewheel flowmeters. However, these meters suffered from low availability and required regular maintenance due to their rotating parts. In particular, maintenance work on the paddlewheel meters affected the coolant supply to the servers and often required parts of the system to be throttled or shut down. This resulted in reduced availability of server capacity and, over time, a decrease in overall data center availability.

The customer was therefore looking for more reliable yet cost-effective flowmeters to replace the paddle-type meters with minimal installation effort. The plan was to deploy the new flow instrumentation on various coolant pipelines ranging from 2" to 16".

The customer decided to gradually replace all paddle-type meters at the various data center sites with the OPTISONIC 6300. The ultrasonic clamp-on flowmeter is suitable for any type of heat transfer medium – conductive and non-conductive. As a non-intrusive flowmeter, it can be easily retrofitted without cutting pipes or interrupting the cooling process, using grease-free permanent coupling pads.

This clamp-on version is powered and designed for permanent installation. It consists of a robust stainless steel sensor rail with two integrated transducers. Its clamp-on rail is highly versatile and can be easily attached to virtually any pipe up to DN4000 / 160".

The OPTISONIC 6300 was selected with a wall-mounted signal converter, featuring a wide range of device and process diagnostics to monitor constant flow conditions and meter performance. The conversion of the meters was completed within just a few days without the need to shut down operations. Apart from the temporary removal of insulation, no cutting or welding of the pipes was required to mount the clamp-on flowmeters.

The data center operator benefits from reliable, long-term stable measurement, helping to ensure continuous cooling of the servers and maintain high data center uptime. The wide measurement range of the ultrasonic clamp-on flowmeter enables safe operation of the system – even under partial load and reduced cooling capacity.

The internet company also benefits from lower operating costs when monitoring the coolant supply. Unlike paddlewheel flowmeters, clamp-on flowmeters operate maintenance-free. Since the OPTISONIC 6300 is a non-invasive device, there is no wear on rotating parts, which made the previously used meters susceptible to damage, drift and recalibration. Furthermore, its transducers can be installed with permanent coupling pads, which eliminates the need for re‑greasing.

The KROHNE clamp-on flowmeter allows for quick replacement of existing meters without mechanical modifications to the piping. It can therefore be easily retrofitted into existing installations with paddlewheel, turbine, and other mechanical flowmeters with rotating parts. Since the clamp-on meter does not come into contact with the medium, it ensures a safe, leak-free installation with reduced installation costs. The clamp-on meter can be installed or removed without interrupting the process.