2.4 Temperature and Humidity Requirements

Airflow through the Oracle PCA is from front to back. For information, see Section 2.5, “Ventilation and Cooling Requirements”.

Studies have shown that temperature increases of 10 degrees Celsius (15 degrees Fahrenheit) above 20 degrees Celsius (70 degrees Fahrenheit) reduce long-term electronics reliability by 50 percent. Excessive internal temperatures might result in full or partial shutdown of the Oracle PCA.

Table 2.6 lists the temperature, humidity and altitude requirements for operating and non-operating systems.

Table 2.6 Temperature, Humidity, and Altitude Requirements


Operating Requirement

Non-operating Requirement



5 ° to 32 ° Celsius (59 ° to 89.6 ° Fahrenheit)

-40 ° to 70 ° Celsius (-40 ° to 158 ° Fahrenheit)

For optimal rack cooling, data center temperatures from 21 ° to 23 ° Celsius (70 ° to 47 ° Fahrenheit)

Relative humidity

10 to 90 percent relative humidity, non-condensing

Up to 93 percent relative humidity

For optimal data center rack cooling, 45 to 50 percent non-condensing


3,048 meters (10,000 feet) maximum

12,000 meters (40,000 feet)

Ambient temperature is reduced by 1 ° Celsius per 300 meters above 900 meters altitude above sea level

Set conditions to the optimal temperature and humidity ranges to minimize the chance of downtime due to component failure. Operating an Oracle PCA for extended periods at or near the operating range limits, or installing it in an environment when it remains at or near non-operating range limits could significantly increase hardware component failure.

The ambient temperature range of 21 ° to 23 ° Celsius (70 ° to 74 ° Fahrenheit) is optimal for server reliability and operator comfort. Most computer equipment can operate in a wide temperature range, but near 22 ° Celsius (72 ° Fahrenheit) is desirable because it is easier to maintain safe humidity levels. Operating in this temperature range provides a safety buffer in the event that the air conditioning system goes down for a period of time.

Relative humidity is the percentage of the total water vapor that can exist in the air without condensing, and is inversely proportional to air temperature. Humidity goes down when the temperature rises, and goes up when the temperature drops. For example, air with a relative humidity of 45 percent at a temperature of 24 ° Celsius (75 ° Fahrenheit) has a relative humidity of 65 percent at a temperature of 18 ° Celsius (64 ° Fahrenheit). As the temperature drops, the relative humidity rises to more than 65 percent, and water droplets are formed.

The ambient relative humidity range of 45 to 50 percent is suitable for safe data processing operations. Most computer equipment can operate in a wide range (20 to 80 percent), but the range of 45 to 50 percent is recommended for the following reasons:

  • Optimal range helps protect computer systems from corrosion problems associated with high humidity levels.

  • Optimal range provides the greatest operating time buffer in the event of air conditioner control failure.

  • This range helps to avoid failures or temporary malfunctions caused by intermittent interference from static discharges that may occur when relative humidity is too low.


Electrostatic discharge (ESD) is easily generated, and hard to dissipate in areas of low relative humidity, such as below 35 percent. ESD becomes critical when humidity drops below 30 percent. It is not difficult to maintain humidity in a data center because of the high-efficiency vapor barrier and low rate of air changes normally present.