ASHRAE recently announced the publication of the second edition of “Liquid Cooling Guidelines for Datacom Equipment Centers.”

“There is an increasing interest in liquid-cooled IT (information technology) equipment at the rack, equipment, and component levels,” Don Beaty, publication chair of ASHRAE Technical Committee 9.9, Mission Critical Facilities, Data Centers, Technology Spaces and Electronic Equipment, which authored the book, 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 said the addition of liquid classes can have an effect on the industry similar to the creation of supply-air-temperature classes, 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 greater than 45°C (113°F), which opens up possibilities for using the rejected heat for building heating systems,” Beaty said.

The book provides guidance related to interfaces between chilled-water and technology-cooling systems and discusses liquid-cooled systems that attach to a datacom electronics rack to aid thermal management.

Also included are updated references and information on approach temperatures and liquid-immersion cooling and guidance related to water-quality problems and wetted-material requirements.

Additionally, the guide defines liquid and air cooling in the context of IT equipment and provides an overview of chilled- and condenser-water systems and other datacom-equipment cooling options.

The cost of the second edition of “Liquid Cooling Guidelines for Datacom Equipment Centers” is $46 for ASHRAE members and $54 for non-members. Copies can be ordered by phone at 800-527-4723 (United States and Canada) or 404-636-8400, by fax at 678-539-2129, or online at