Air temperature and humidity level at the inlet of each chassis inside a cabinet are a true indication of environmental conditions. It may be difficult to take these measurements at each chassis, since it requires attachments of multiple probes inside the cabinet with the door closed.
As an alternative, the temperature and humidity levels at the chassis inlets can be derived by measurements taken outside the cabinet door, as illustrated in this section.
- Without instrument readers
- Place temperature and humidity probes approximately 0.64 cm (0.25 in.) in front of the opening near the bottom of the cabinet’s front door.
- With instrument readers
- If using one of the instrument readers recommended under Environmental Measurement Instruments, orient the air flow impellers parallel to the door inlet vents, so that air going into the door opening will pass through the impellers and sensors.
Humidity measurements taken outside and inside the cabinet door are generally the same. However, air temperature measurements taken outside and inside the door can differ. To estimate the maximum air temperature at the chassis inlets inside the cabinet door, the general rule is to take two readings outside the front door, calculate an average temperature, then add 5° C (9° F).