Editing 19-inch rack (section)

==Cooling==
{{main|Computer cooling#Servers}}
There is no standard for airflow and cooling of rack-mounted equipment. A variety of airflow patterns can be found, including front intakes and rear exhausts, as well as side intakes and exhausts. Low-wattage devices may not employ active cooling, but use only passive thermal radiation and [[convection]] to dissipate heat.

For rack-mounted computer servers, devices generally intake air on the front and exhaust on the rear. This prevents circular airflows where hot exhaust air is recirculated through an adjacent device and causes overheating.

Although open-frame racks are the least expensive, they also expose air-cooled equipment to dust, lint, and other environmental contamination. An enclosed sealed cabinet with forced air fans permits air filtration to protect equipment from dust.

Large server rooms will often group rack cabinets together so that racks on both sides of an aisle are either front-facing or rear-facing, which simplifies cooling by supplying cool air to the front of the racks and collecting hot air from the rear of the racks. These aisles may themselves be enclosed into a cold air containment tunnel so that cooling air does not travel to other parts of the building where it is not needed or mixes with hot air, making it less efficient. [[Raised floor|Raised or false floor]] cooling in server rooms can serve a similar purpose; they permit cooling airflow to equipment through the underfloor space to the underside of enclosed rack cabinets.<ref>{{Cite web|url=https://schroff.pentair.com/en/schroff/cooling|title=Data Center Cooling {{!}} Pentair|website=schroff.pentair.com|language=en|access-date=2017-08-27|archive-date=2017-08-27|archive-url=https://web.archive.org/web/20170827210722/https://schroff.pentair.com/en/schroff/cooling|url-status=dead}}</ref>

A difficulty with forced air fan cooling in rack equipment is that fans can fail due to age or dust. The fans themselves can be difficult to replace. In the case of network equipment, it may be necessary to unplug 50 or more cables from the device, remove the device from the rack, and then disassemble the device chassis to replace the fans.

However, some rack equipment has been designed to make fan replacement easy, using quick-change fan trays that can be accessed without removing the cabling or the device from the rack, and in some cases without turning off the device so that operation is uninterrupted during replacement.