Liquid Cooling Guidelines for Datacom

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Supply Water Temperature Classification New Addition to Updated Guidance on Cooling Data Centers

ATLANTA— Data center rack heat loads are steadily climbing, creating a need for liquid cooling solutions to reduce the volume of airflow needed, as well as lower processor temperatures for better computer performance. “Liquid Cooling Guidelines for Datacom Equipment Centers,” second edition, recently published by ASHRAE, provides best practice guidance for implementing liquid cooling systems in data centers.

“There is an increasing interest in liquid cooled IT equipment at the rack, equipment and component levels,” Don Beaty, publication chair of Technical Committee 9.9., Mission Critical Facilities, Data Centers, Technology Spaces and Electronic Equipment, said.  “There is also increased interest in reuse of the heat rejected from IT equipment. One of the more important changes to the second edition is the addition of supply water temperature classification.”

Beaty claims that the addition of liquid classes can have a similar effect on the industry as the creation of supply air temperature classes did—which was the critical enabler to the use of economizers in data centers.

“There are five water temperature classes with the highest temperature class being >45 C (113 F), which opens up possibilities for using the rejected heat for building heating systems,” he said.

The guide bridges the liquid cooling systems by providing guidelines on interface requirements between the chilled-water system and the technology cooling system and on the requirements of liquid-cooled systems that attach to a datacom electronics rack to aid in data center thermal management.

Also included are updated references and further information on approach temperatures and liquid immersion cooling, plus guidance on water quality problems and wetted material requirements.

Additionally, the guide covers definitions for liquid and air cooling as they apply to IT equipment, along with an overview of chilled-water and condenser water systems and other datacom equipment cooling options.

This book is the fourth in the ASHRAE Datacom Series, authored by ASHRAE TC 9.9.

The cost of “Liquid Cooling Guidelines for Datacom Equipment Centers,” second edition, is $54 ($46 ASHRAE members). To order, contact ASHRAE Customer Contact Center at 1-800-527-4723 (United States and Canada) or 404-636-8400 (worldwide), fax 678-539-2129, or visit

ASHRAE, founded in 1894, is a global society advancing human well-being through sustainable technology for the built environment. The Society and its more than 50,000 members worldwide focus on building systems, energy efficiency, indoor air quality, refrigeration and sustainability. Through research, standards writing, publishing, certification and continuing education, ASHRAE shapes tomorrow’s built environment today. More information can be found at

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