Flase Floor.Measurement of air leakage.Testing Procedures.

It is used in places, where a large amount -mostly electronic - equipment is packed together in rows of racks or cabinet, like internet hubs, server farms, large computing centers, supercomputers. You get the idea. Such equipment generally is positively aircooled: individual fans or blowers force the required air volume thru each equipment. (Some IBM mainframes were cooled by chilled water, an expensive proposition.) So, by design you should only worry about delivering the right amount of chilled air to every point on the floor it is needed. Pressure will be whatever it takes to do that delivery. That is not your problem, as it will be the result of general airconditioning design, done by people doing that part of the job for a living. They will tell you, what size ducting is needed in supply, plenum and return to get the job done.

What will come back, and bite you and your colleagues firmly in the behind, is lack of foresight on somebodies part. It will take a bit to explain, but it is not complicated. Equipment comes in three flavors: Cabled strictly in overhead trays, cabled under the raised floor and don't care. But planning committees normally look at today's requirements. What happens in real life is, that in 3-10 years later equipment moves out and the new one is a different kind. To make it worse, equipment power density (heat thrown of by a given volume) is doubling reliably every 4 - 7 years. So, what to do? I would design the floor and ducting, and airconditioning room size with a, say 20 years in the future requirement in mind. And for now I would put in as many air handlers, chillers etc. that I need now.

And when (not if) somebody tells you they need only so much raised floor to accomplish it, double it, at least in height. In a few years somebody will bring in equipment, whose cabling will virtually choke airflow in the plenum otherwise.

How do I know it? My computer center was consuming 200kW on a winter day and 500kW on a hot summer day. Time and again the floor could not be packed tight enough because the cooling could not support that dense heat removal. And the electronic guys, wanting the shortest cabling were not happy about it.

Later add-ons for enhanced cooling are a cramp, and never a quite satisfactory solution.

To check out the airconditioning's working is not a big deal. Pressures in the ducts, temperature differences and current consumption of the air handlers will give that via manufacturer's charts. If you worry about heat load carrying capability still, rent a few 50 - 100 kW heat loads (very large toasters) for the cerification test. And the raised floor leaks, what it leaks. Nobody can do a thing about it. I kept winter shoes and winter pants in my office to work on that floor: it is unpleasant to walk in a 13Cdegree (50Fdegree) air knee deep without them.