Table of Contents
Advertisement
Ventilation requirements
This section describes how to determine the ventilation requirements for a Matrox
Helios system enclosure. Ventilation moderates the steady-state internal
temperature rise in the enclosure; the sum of the temperature rise and the room
operating temperature should not exceed the maximum operating temperature
supported by Matrox Helios. Note that the figures mentioned assume near sea
level atmospheric pressure and a room operating temperature near 25
This section is only an introduction to thermal management; you can refer to the
web site of a fan manufacturer for more detailed information on this subject. For
example, you can refer to the engineering information provided on the site of the
Sunonwealth Electric Machine Industry Company (www.sunon.com.tw).
Basic equation
The basic equation to determine how much air flow is required in the enclosure
is as follows:
Q(cfm)
= 1.76 x P/dTc
3
= 0.05 x P/dTc
Q(m
/min
)
Q:
Required air flow (m
P:
Internal heat dissipation (W)
dTc:
Internal temperature rise (°C)
The enclosure size does not influence steady-state internal temperature rise; it only
affects the dynamic character of the rise. A larger enclosure takes more time to
attain a steady state.
To properly select a fan for your enclosure, you must estimate the pressure build-up
in your enclosure. To do so, you need to estimate the relationship between the fan
size, the opening of the enclosure on the intake side, and the opening of the
enclosure on the exhaust side.
If your intake and exhaust opening is bigger than the fan area, your enclosure
should not build any pressure. Due to turbulence, cabling, and direction change
of the air flow in the enclosure, there is always some pressure build-up, even if the
intake and exhaust openings are sufficient. A typical desktop computer enclosure
builds up around 3.75 mm of H
3
/min or cfm (cubic feet per minute))
O of pressure.
2
Ventilation requirements
°
C.
157
Advertisement
Table of Contents
