User guide

Thermal Considerations
59 AT8910/AT8940
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6.1.3 System Airflow
The airflow impedance (pressure) curve gives multiple information and tips about thermal operational range
of the system carrying the AT8940. Once volumetric airflow capability of your chassis is known, the pressure
curve can help determine the ambient (room) temperature setpoint that should be used for optimal
operation. If you are using various models of ATCA blades into the same chassis, it is possible to find the best
thermal fit. Having the volumetric airflow value for each chassis slot, it is then possible to decide the layout
using the pressure curves.
Table 6-2:Pressure curve AT8940
Figure 6-1:Pressure Drop Curve
Test Poin Airflow (CFM) Pressure drop (in H2O) Airflow (m³/h) Pressure Drop (Pa)
1 5 0.005 8.5 1.3
2 10 0.017 17.0 4.3
3 15 0.032 25.5 8.1
4 20 0.050 34.0 12.6
5 25 0.071 42.5 17.8
6 30 0.095 51.0 23.7
7 35 0.122 59.5 30.5
8 40 0.152 68.0 37.9
9 45 0.185 76.5 46.1
10 50 0.221 85.0 55.0
11 55 0.260 93.4 64.6
12 60 0.302 101.9 75.0