Because the data center industry has years of experience with hot and cold aisle containment, now is an excellent moment to document some best practices to assist future projects to run successfully.
Despite the ground-breaking achievements and new endeavors, we still continue to see hiccups here and there with containment design, specifications, and drawings.
So, in this blog, we have formulated ten easy questions and their best possible answers in order to help you craft a state-of-art, efficient hot or cold aisle containment system for your new data center project.
So, let’s get into it without further ado!
What Do You Mean By Containment Topology?
The necessity for “rack independence” is the primary driving force for topology selection. For example, suppose the IT deployment plan asks for specific pieces of equipment to be added and swapped during the life of the data center. In that case, a rack-supported topology is appropriate because the racks themself should be stable. On the contrary, if the IT deployment plan asks for entirely occupied server racks to be deployed and changed out over time, ceiling-supported or floor-supported containment is advisable to stop interrupting the containment when changing the racks.
Some other drivers for topology choice consist of IT use model, ceiling height, cooling architecture, and weight-bearing capacity of the building’s roof and requires for phased or flexible deployment.
Do You Want To Contain Hot Aisle Or Cold Aisle?
The answer to this question largely depends upon 3 factors: the site type, enterprise vs. the third party, and the site’s architecture. We choose hot aisle containment in a classic raised floor with perimeter cooling because the common above floor cold zone is simpler and more lenient to balance. With cold aisle containment with roofs, each aisle needs to be individually balanced with utmost care and control.
In colo/wholo, conversely, where the aisle layout is expected to change over time, rack-based cold aisle containment with roof panels is the most popular option.
What Rack Sizes Have To Be Accommodated?
Let’s take the floor-mounted containment system as our case study, for example. These systems usually have an upper level and a lower level and a fixed beam between the two.
This beam serves as the fixed elevation height for which the racks must be accommodated. The beam height also determines the height of the upper panels and any lower level InFill panels that are delivered on Day 1 to make up for missing racks.
Add to it a last-minute decision to switch from a 42U rack design to one for 48U racks, resulting in a height difference of nearly 12 inches. This alteration affects three essential items: the floor-mounted frame system itself, the above rack panels, and the lower level InFill panels, which must be shortened 12 inches and extended 12 inches, respectively.
Will Your Above-Rack Panels Be Removable Or Fixed?
Removable ones are expensive, while the fixed panels cost less.
The purpose of a detachable upper panel is to enable access to cable trays/power buses via the containment. If the design calls for vertical panels on the cold face of the cabinets, a fixed panel may suffice, while cable tray cut-outs in the panels will almost certainly be required. When you have cable tray cut-outs, describe how you want them sealed.
What Is Your Containment’s Air Tightness Standard?
Ideally, the HACS/CACS should have containment integrity with a coupled open surface area that doesn’t exceed 3% of the total contained zone surface area. The containment integrity of the HACS/CACS must be such that no gaps greater than 0.25 inches exist. Door bottom gaps could be up to 1.0 inches wide because they act as safety pressure relief pathways when exhaust and supply air become out of balance.
This is simple to measure and validate in the field, and it is more than enough for proper airflow management in the room.
What Fire Rating Is Required For Your Materials?
It is critical to assess the fire rating required for the prospective materials you intend to use. Materials that fulfill the ASTM e84 Flame and Smoke spread rating of Class B are required by NFPA containment regulations. Thankfully, the majority of containment is made of twin wall polycarbonate, which has a Class A classification. The fire rating must also be mentioned when a design calls for “solid, clear” door inserts and containment panels. Otherwise, you will receive low-quality Acrylic inserts that do not fulfill the e84 standard.
Because there are no feasible Class B rated materials for brush grommets and air dam foam, we encourage specifying that “gap filling” materials used for small scale applications fulfill the UL-94 rating.
Are You Ensured By Factory Mutual Global?
The thing with Factory Mutual Global is that the cost of confinement materials will be roughly double (yes, double!) that of a regular containment project. This is because FM Global has specific containment criteria for its clients, one of which is to employ FM4910 compliant material.
What’s The Deal With Missing Racks During Commissioning?
Today, most data centers use pressure differentials between hot and cold aisles to regulate cooling. Full containment is required in this case to provide a pressure differential barrier for testing and running the cooling system. There will be a commissioning issue if the containment is a rack independent design and there are no racks. We’ve seen operators utilize cardboard, plywood, and plastic sheeting to close up the aisles during testing to address the “Oops, large gap” problem. Of course, after the temporary patch is removed, the cooling system will be left without a pressure differential to drive it until all of the racks are fitted.
How Can You Seal The Various Small Gaps?
Aside from containment doors and panels, each project has its own set of other minor gaps that must be closed. Gaps above, below, and between racks, as well as gaps around cable tray penetrations, are good candidates. Plastic skirts, air dam foam, brush grommets, and vinyl flaps are standard methods for closing these spaces. Because these goods are used on a limited scale, the UL-94 fire rating for gap sealing skirts and foam is adequate.