19ZollNorm

19ZollNorm, also known as the 19-inch rack standard, is a widely adopted specification for the physical dimensions of electronic equipment, particularly servers and networking devices. The standard was developed to ensure compatibility and interoperability between different manufacturers' products. The term "19ZollNorm" is derived from the German word for "19-inch," reflecting the origin of the standard in Europe.

The 19-inch rack standard defines the dimensions of the rack itself, as well as the size and positioning of the equipment units that can be mounted within it. The rack is typically 19 inches (482.6 mm) wide and can be any height, with the most common sizes being 42U (42 rack units) and 48U. Each rack unit (U) is 1.75 inches (44.45 mm) high, allowing for precise stacking of equipment.

The standard also specifies the dimensions of the equipment units, which are typically 1U, 2U, 3U, or 4U in height. This allows for a modular approach to equipment placement, enabling data centers and server rooms to be efficiently organized and managed.

The 19-inch rack standard has become a de facto industry standard due to its widespread adoption and the benefits it provides in terms of compatibility, scalability, and ease of management. It is used in data centers, telecommunications facilities, and other environments where electronic equipment is deployed in racks.