The heat dissipated by electronic equipment continues to increase at a alarming rate. This has occurred for products covering a wide range of applications. Manufacturers of this equipment require that the equipment be maintained within an environmental envelope in order to guarantee proper operation. Achievement of these environmental conditions are becoming increasingly difficult given the increases in rack heat loads and the desire for customers of such equipment to cluster racks in a small region for increased performance. And with the increased heat load of the racks and correspondingly increased air flowrate the chilled air flow supplied either through data center raised floor perforated tiles or diffusers for non raised floors is not sufficient to match the air flow required by the datacom racks. In this case some of the hot air exhausting the rear of a rack can return to the front of the rack and be ingested into the air intake thereby reducing the reliability of the electronic equipment. This paper describes a method to reduce the effect of the hot air recirculation with a water cooled heat exchanger attached to the rear door of the rack. This heat exchanger removes a large portion of the heat from the rack as well as significantly lowering the air temperature exhausting the rear of the rack. This paper describes the hardware and presents the test results showing that a large portion of the heat is removed from the rack and the temperature exhausting the rear of the rack is significantly reduced. Finally the effectiveness of the solution is shown in modeling of this water cooled solution in a data center application.

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The fatigue resistance of 6 inch Schedule 40 PVC solvent-bonded pipe fittings was investigated. It has often been assumed that the performance of PVC fittings is comparable to that of the corresponding pipe. The results of this study indicate that the fatigue performance of PVC fittings is much lower than that of the pipe. Several fittings were exposed to a repetitive surge cycle of 90 to 180 psig at a rate of 0.11 1 hertz. Failures of several tees occurred between 13,000 and 16,000 cycles, much sooner than the predicted lifetime of pipe under these conditions.