Understanding the Data Center humidity control

One of the most common threads that all the data center facilities are facing are the humidity changes in the environment. But how important data center humidity control is and why? We will start with the basics. The water vapor in the air is known as humidity. If the relative humidity (HR) is zero, there’s no water vapor in the air and if the HR is 100%, the air is holding the maximum possible water vapor.  

Also, humidity and temperature must be measured and analysed together. When the air is cooled, the relative humidity (HR) increases until the water starts condensing (reaching the dew point). Higher or lower Humidity levels in the IT equipment environment can lead to equipment failure.

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High Humidity associated risks for Data Centers

High humidity levels can lead to metal components corrosion. According to some recent studies, increasing relative humidity from 50% to 70% is not affecting the corrosion unless Chlorine is present, but further increasing relative humidity to 80% also increases the corrosion regardless of all gas mixtures. For data center facilities expected to have Cl2 and/or H2S, the humidity levels should be kept lower than 60%. At least twice in a year, the facility operators should test the corrosion levels. Data center humidity control should take care of high humidity but also low humidity, let’s see in the next paragraph about this last one.

Low Humidity associated risks for Data Centers

It is well known that low humidity can lead to static electricity release and electrical discharges due to the air conductivity increase. As per the research studies carried out by ASHRAE, there is a significant reduction of electrostatic charge accumulation on personnel if ESD (Electro Static Discharge) control shoes are worn, regardless of the flooring. Also, there’s a benefit in charge accumulation reduction if a good conductive floor is installed, regardless of footwear.

How to properly measure humidity?

Temperature and humidity measurement sensors are highly recommended in a data center facility because of the following reasons:

1.- Facility health and audit tests.

1.1- Aisle measurements and locations: These measurements will ensure that the aisle temperature and humidity levels are within the allowable and recommended ranges.

The locations of the sensors should be: 

    • One point for every 3m to 9m of aisle or every fourth rack position.
    • Points located midway along the aisle and centered. 

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1.2- HVAC Operational Status: Measure and record the following status points at the HVAC units:

    • Operating status ON/OFF.
    • Supply fan status ON/OFF.
    • Supply air temperature and return air temperature.
    • Supply air humidity and return air humidity.


2.- Equipment installation verification tests.

The objective of these tests is to ensure that the bulk temperature and humidity in front of the cabinet or rack are acceptable, as below:

    • Measure and record temperatures and humidity at the geometric center of the air intake of the top, middle and bottom equipment.
    •  All temperature and humidity values should fall within the specifications for the class environment specified.

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As we have seen, monitoring the environment conditions in a data center is critical to ensuring uptime and system reliability, that is why in ARANER we keep close attention to Data Center humidity control in all of our projects. Are you?

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