IBM 9835-415, Deployment Manual

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These levels can be achieved with normal cable exits from the rack and with a
small amount of hot air bypass at the base of the door (small amounts of hot air
might escape from the rack without being cooled by the door).
Water temperatures below 18°C (64.4°F) can be used only if the system that is
supplying the water is able to measure the room dew point conditions and is able
to automatically adjust the water temperature.
Another example of performance data is shown in Figure 15 on page 41 for
identical conditions as in Figure 14, except reflecting a 20 kW heat load. Because of
the lower heat load, a specific level of cooling can be achieved with warmer water,
a lower flow rate, or both.
Figure 14. Typical performance of a rear-door heat exchanger, 32 kW heat load. Percentage heat removal as function
of water temperature and flow rate. (24°C (75.2 °F) rack inlet air, 32 kW rack load, 1530 cfm air through the rear-door
heat exchanger)
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IBM FlashSystem A9000R Models 9835-415 and 9837-415 Deployment Guide