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Data Center Cooling, Dehumidification, and Maintaining Safe Humidity Levels09 Apr

Regulating humidity levels is imperative for the proper functioning of equipment in data centers. The challenge comes in ensuring that the air in a computer room does not hinder the normal operations of the room. A standard computer room usually has a relative humidity ranging between 45% and 85%. On the other hand, literature from research conducted on the same topic 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 buildings or residential houses where fluctuations in humidity level are frequent and relatively high, the overall moisture condition of data centers should be generally low. That is because in most centers, few people are working at one time, and the cooling coils dehumidify. Therefore the only two sources of humidity are outside air, which is unconditioned and the possible malfunction of Computer Room Air Conditioners (CRAC). Variations in moisture often occur when different CRAC components ‘fight’ each other, with some units cooling, while others are humidifying.

The only other possibility of having high moisture levels in a data center, 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, because the original building model was not conducive to maintaining optimal humidity levels required for a data center.

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 the 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 a detrimental effect. For instance, moisture intrusion in polymer parts of circuitry and other passive subsystems could result in the swelling of these components. Consequently, there may be residual stresses created, which may eventually cause these components to crack.

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, 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
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 flow of electricity. Aside from that, fluctuations that exceed 6% in an hour may affect tape drives, which may then have to be recalibrated.

All these instances 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 dehumidifiers can be used to control air moisture, there are two which have been proven to be most appropriate for use in data control centers.

Desiccant Dehumidifier
A desiccant dehumidifier is a special type of humidifier since it neither has evaporator coils (cooling metal coils) nor any refrigerant. Contrary to that, they have a hygroscopic material (desiccant) that absorbs 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 the air below the dew point, resulting in condensation of moisture. It has a fan that sucks in the air through the system, and the air passes through a compressed cooling system, which consists of a pressurized circulating refrigerant. As air comes into contact with the condensers, water droplets are formed which then accumulate in 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 is capable of getting 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.