Data Center Cooling, Dehumidification and Maintaining Safe Humidity Levels

Regulating humidity levels is imperative for the proper functioning of equipment in data centers. However, the challenge comes in ensuring that a regular computer room air does not hinder the normal operations in the room. A standard computer room usually has a relative humidity ranging between 45% and 85%. On the other hand, literature from many researchers conducted on the same recommends that this relative humidity should be maintained between 40% and 55%, with ranges between 20% and 80% regarded as acceptable.

Causes of High Humidity in Data Centers

Unlike ordinary constructions or residential houses where fluctuations in humidity levels are frequent and relatively high, the overall moisture condition on data centers should be generally low. That is because in most centers, few people are working and the cooling coils dehumidify. Therefore the only two sources are outside air which is unconditioned and possibly malfunctioning of Computer Room Air Conditioners (CRAC). Often variations in moisture occur when different CRAC components ‘fight’ each other, with some units cooling while others are humidifying.

The only other possibility of having a data center with high moisture is if the structure was not originally designed to become a data center. For instance, there was a structure that had been originally designed and constructed to be a warehouse and was later converted to a data center. The owners of this center had constant problems with regulating their air moisture.

Effects of Humidity

The atmospheric moisture can raise concerns in data centers depending on the equipment being used as follows:

High Humidity

When the atmospheric moisture is high, it can result in condensation of water on equipment. While this condensation could have a negligible effect when it occurs on the computer chassis, its impact on electrical components could have detrimental effects on the functioning of the equipment.  For instance, moisture intrusion in polymer parts of circuitry and other passive subsystems could result in swelling of these components. Consequently, there may be residual stresses created which may eventually cause cracking of these components.

Very Low Humidity

If the humidity control mechanisms are inadequate and defective, it may result in very low humidity, which also has its downsides:

In cases where there is very low humidity in data centers, high static charges are generated. Usually, the air moisture dissipates static electricity. That is because water is conductive, and allows electric charges to travel freely in the atmosphere. Since this is not the case, the static charges will be transferred between different electrical components in close proximity. As a result, delicate computer systems such as the RAM, motherboards, and processing units may be damaged.

Fluctuations in Humidity

Study findings from several studies have proved that variations in humidity levels can cause uneven expansion and contraction of circuit boards. With time, the circuit weakens or even cracks which can hinder the normal electric flow. Apart from that, fluctuations which exceed 6% in an hour may affect tape drives, which may have to be normalized again.

All these may increase the overall equipment replacement bills, and in extreme cases, there may be permanent loss of data.

How Can You Regulate Relative Humidity in Data Centers

Installing dehumidifiers is the most effective way to monitor and control relative humidity within the desired range (40% to 55%). Even though several types of humidifiers can be used to control air moisture, there are two which have been proven to be appropriate for use in data control centers.

Desiccant Dehumidifier

A desiccant dehumidifier is a special type of neither humidifier since it neither has evaporator coils (cooling metal coils) nor any refrigerant. Contrary to that, they have a hygroscopic material (desiccant) which adsorbs moisture from the air. Once they are saturated, they are then recharged by a heater, which reverses the chemical process, causing it to lose the moisture it had absorbed.

Condensation Dehumidifier

A condensation dehumidifier operates by a principle of cooling of air below the dew point, resulting in condensation of moisture. It has a fan that sucks in air through the system. The air passes through a compressor cooling system, which consists of a pressurized circulating refrigerant. As air comes into contact with the condensers, water droplets are formed which then accumulate at the condensation tank. The air then passes to the other side with much lower humidity.

Which is the Best Dehumidifier for Your Data Center?

A condensation dehumidifier is considered the most appropriate because it is relatively cheaper than a desiccant dehumidifier. Additionally, it is more effective at higher humidity and temperature levels. That means that it can get rid of large amounts of atmospheric moisture.

After all, is said and done, it is essential that you involve an expert when you finally decide to protect your data center from humidity.

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