Free-cooling and air purification in the data center: how and why to purify the air?

    Our equipment is installed in a number of data centers located in the USA, the Netherlands and a couple of countries. In one of the data centers where our servers are located, free-cooling is used. In general, there is no news in this, because in regions with a cool climate it is quite possible to use external air for cooling.

    But, as it turned out, freecooling can be a problem. One day, a conversation began with colleagues who have to keep equipment in one of the data centers in South Asia. As it turned out, freecooling is also used to cool equipment in this DC. Everything would be fine, but they often have equipment failures. After a detailed analysis of the problem, it turned out that "the casket just opened." The main problem is in the dirty air, which is not cleaned well enough.

    Research on the negative impact of industrial air pollution on server hardware and data centers in general has been ongoing for a long time. One of the most extensive research conducted by Intel . But the results of this study are a simple statement of the fact that polluted air increases the wear rate of equipment in a number of regions. More productive can be called a study by Baidu regarding its data centers, which are located in Beijing. I must say that this company needs DCs in this region, but there are almost more problems as a result than advantages.

    The essence of the problem

    After studying the problem, it turned out that a number of companies have long been offering special filters for DC cooling systems located in various regions. Somewhere air purification is almost not needed at all, and somewhere very thorough cleaning is needed. Moreover, air purification can positively affect the energy efficiency of the data center.

    The fact is that high-quality filters help reduce costs. If you clean the air of dust, then in this case the overall load on the equipment cooling system is reduced. And this leads to a decrease in energy consumption. In addition, when cleaning air from dust and gases (the same sulfur compounds), the operating life of the equipment also increases. So the probability of damage to individual components or the failure of the entire server is significantly reduced. The elimination of such a problem is a cost, and very significant.

    In some cases, experts point out that when cleaning the air used to cool equipment, PUE is reduced. And this means reducing costs and improving the reputation of the facility and the operator company.

    As for Asia, the problem here is still high humidity. Atmospheric pollution with sulfur compounds, coupled with high humidity (60% and above) has a negative impact on the operation of the equipment. The fact is that as a result, the metal parts of the equipment corrode, and quite quickly.

    Possible Solution

    Freecooling is good, but it can not be used everywhere. This cooling method is ideal for environmentally friendly regions with minimal atmospheric pollution.

    But if a data center in a not-so-clean region works with freecooling, then it is worth using air filtration. Such a system should remove not only dust, but also gas pollution. The most effective filters in this regard are those where the working parts contain microfibres of glass. Such filters are durable and reliable.

    Now the European standard EN779: 2012 has been developed for air filters. Based on the experience of colleagues, we would recommend using F7 class solutions where the air is dirty. If the standard ISO 14644-1 1999 is used, then it is necessary to check whether the atmospheric air samples comply with ISO 8 class.

    In the presence of industrial gases (NOx, SOx and H2S), activated carbon filtration systems must be used. Only they can effectively absorb aggressive gaseous components.

    A number of companies also recommend autonomous air purification units. Such auxiliary units can be used for air purification in those places of the data center where, for any reason, the main cooling and cleaning system cannot be used.

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