Chris Kusel, CFPS, CDT, Director of Engineering, Hilti North America
Firestopping is one of the most critical aspects of building design and construction. This code mandated element of fire protection helps restore the integrity of fire-rated floor and wall barriers when openings are made to accommodate penetrations such as data cable pathways. With only a few small holes in a fire-rated assembly, smoke could migrate throughout a building in a matter of minutes. With significant efforts devoted to risk mitigation in both new build and existing data centers, it is essential that firestop design and installation is executed correctly.
Data cables penetrations present the most unique challenge to firestopping not only due to combustible cable jacketing that can burn away under fire conditions but for another key reason - cable re-penetration. Openings or pathways for data cables are continuously modified or upgraded through the life cycle of a data center. This amplifies the risk even further as cable penetrations that may have initially been fire stopped correctly could easily revert to being non-compliant and leave a facility exposed.
Fire stopping is evaluated in accordance with UL and ASTM testing. Products or “systems” are subjected to multiple fire and pressure resistance requirements which must be met for a firestop system to pass these standards.
Why is this critical, especially for data centers? Most traditional firestop system technologies limit the amount of data cables that can fill a pathway opening to approximately 30%. This is in order to provide a sufficient gap around the cables to install enough traditional intumescent firestop material such as putty or caulking. These intumescent materials would “expand when exposed to heat” closing off the gap in the opening around the cables and prevent fire and limit smoke from passing to the next room or compartment protecting sensitive server equipment and technologies. However, with the extensive number of fiber and/or copper cables through a data center, the 30% cable fill limitation is a major “pain point” of owners and their network designers. How can this challenge be addressed now and throughout the life cycle of the data center? Newer technologies such as firestop cable pathway devices have been developed as “all-in-one” fire and smoke seal solutions allowing 100% visual fill of cables. The built-in fire and smoke technology enhances compliance not only during initial installation but also during the many future upgrades.
However, even beyond firestop requirements, what other challenges could these same data cable openings created in wall and floor assemblies of data center facilities be facing today? Is there a connection between the firestop systems utilized and overall building performance? Could the design choice and correct installation of firestop systems in data centers also impact airflow control to better establish data hall pressurization for proper operation of suppression systems? What about control of dust and whiskers that could damage server equipment? These are important and valid questions and a reality faced today in building construction and operations.
Suppression and alarm systems, along with compartmentation, complete the balanced approach to fire protection. When it comes to mission critical facilities like data centers, there may be no water based sprinklers but instead chemical based suppression systems. These suppression systems rely on the correct firestop system technology that resists airflow to help ensure proper room pressurization for suppression systems to function effectively.
These newer, more innovative firestop cable pathway devices, are not only designed to accommodate modern needs such as cable re-penetration but also easy, one time initial installation improving system correctness which can reduce inspection failures. Finally, to address the issue of airflow for room pressurization and limiting dust and whiskers, these next-level cable pathway device technologies have an advanced feature that enables superior airflow control performance over most traditional methods. Pathway devices are also an easier, more seamless option for BIM design.
To summarize, for owner’s complete pain points or concerns and design considerations, basic firestop products may address minimum needs. However, tested firestop listings with built-in airflow control technology is key. Long term planning for cable network capacity is a critical element of a datacom engineer’s or consultant’s responsibility. The key point to consider is that firestop system technology exists which can address both fire code requirements and additional owner pain points resulting from airflow. The best way to ensure compliance by contractors from the bid through installation phases is by detailing firestop cable pathways on datacom or telecom detail sheets. Next, specifying specific firestop systems and product solutions in divisions 26 & 27 is recommended. As design advances, some project teams have incorporated BIM. This trend should continue to increase throughout the next few years.