Inch By Inch: US versus International Racks

  With rigid hot and cold aisle containment systems, inches are important. Any slight variances matter in the containment world, because the difference of even one inch can dramatically impact the fit and installation of the containment system. To get the containment design right the first time, a designer needs to pay attention to the following:

1.       609mm versus 600mm rack width

APC, Chatsworth, and Rittal racks, among others of their type, are built to 600mm width international standard, which accommodates their global distribution model. More domestically oriented rack makers, like Polargy, Damac, and ElectroRack, provide 24.0” or 609mm wide racks. That 0.4” difference is slight, but it matters when trying to accurately size the containment.

2.       Slab versus raised floor rack to tile alignment

What can be tricky for containment is that on raised floors, as built domestically, the rack layout often aligns to the tiles, leaving a 0.4” gap between each rack for those 600mm racks. It is important to pay attention to this detail when specifying panel sizes.

3.       Groupings of 23.6” racks and if they are gapped by 0.4” or not

When identifying a containment system that is based on the racks, the designer is well served to pay attention to the true rack size.  A 24.0” wide roof panel leaves a 0.4” overlap on a 23.6” cabinet, as illustrated in the photo above. This variance is multiplied ten times for a row of ten racks and the resulting overlap is a whole 4.0”.

4.       The last rack of the row relative to the other racks and their consequent widths and gaps.

What can be especially tricky is the last rack of the row. In the scenario of 23.6” racks aligned to 24” tiles, one would have all 24.0” wide panels but for the last panel, which would be 23.6” since that is where the aisle truly ends. And, if that last panel is sticking out by 0.4”, then it will obstruct the placement of the aisle end door. These subtle differences in measurements between the US and international standards should be specified with deliberation, because in the containment world, inches count.