What is a 19-inch rack?

19-inch rack

19-inch racks are mainly prominent in the music, telecommunications and computer industry. Actually they’re a kind of cabinet or rack to fix 19-inch-wide equipment into. The photo here on the right shows you an example with two pieces of equipment in it.

The inch is an English imperial unit of measurement that corresponds to 2.54 cm. So 19 in are essentially 48.26 cm. Actually this is the standard international width for all electronic equipment to fit into a so-called 19-inch rack. In practice all professional manufacturers of electronic equipment work with this standard.

 

he photo here on the [right] has an example of a 19-inch electronic device. These things typically have holes (this one has 4) at the front to fix them to the rails in the rack, also called ‘rack strips’. Once the equipment is fixed in the rack, (usually) only the front of it is accessible for operating purposes with the connections and cables (usually) at the back.

As you can see in the photos, 19-inch devices typically have a front panel that’s wider than the device itself and 19 in is exactly the width of the front panel.

 

International standards need the rack strips, which the front panel of the device is fixed to, to be 0.625 in (or 15.875 mm) wide, so there's only 17.75 in (or 450.85 mm) left between the strips, because the total width is 0.625 in + 17.75 in + 0.625 in = 19 in. So the front panel is always 19 in wide and the device itself can be maximum 17.75 in, otherwise it wouldn’t be able to fit in between the rack strips.

Rack units (RU or U)

Not only the width of 19-inch equipment is standardised, height is too. The height of a device must always be a whole multiple of one so-called ‘rack unit’ or 1U. 1U equals 1.75 in or 44.45 mm. So the height of all 19-inch equipment is a whole multiple of 1U and we talk about equipment of 1U, 2U, 3U, etc.

This device, for example, is 1U high: FBQ1502, this one 2U: FBQ3102 and this one 3U: FBQ6200. You can easily check how many U any of your devices are on their spec sheet. The technical specifications will also tell you the dimensions. The last piece of equipment, for instance, is 5 and 1/4 inches high, which equals 3 x 1.75 in or 3U.

19-inch rack case

A 19-inch rack doesn’t necessarily have to be a flight case. You could just mount rack strips vertically on two upright wooden panels and then fix your equipment on those. People often do: recording studios, for example, and home DJs as well. But if you’re often on the road, it might be useful to build a 19-inch rack into a flight case.

Step-by-Step Assembly Instructions - Building a 19-inch rack case

Web shop

You’ll find aluminium and steel rack strips in the flightcase-brico.com web shop. The steel ones are stronger, of course, but aluminium ones will do just as well for lots of equipment.

Really heavy devices (like heavy power amplifiers, for instance) also have fixing holes at the back, but these are in a different direction. See for example QSC RMX2450. For this device you need the single steel rack strips at the front, and the double steel rack strips at the back.

For each hole, you need a cage nut, a bolt and a washer. These are available in the flightcase-brico.com web shop in sets of 8. Be careful though, because there are different sets for aluminium and steel rack strips.

 

There is a wide range of 19-inch parts available in the web shop and you can also get step-by-step instructions to build your own 19-inch rack case.