Tuesday, July 28, 2015

The Library's Fire Suppression (Sprinkler) System

The construction project reached a milestone this month when the installation of a fire suppression (sprinkler) system throughout the lower floors of Howard-Tilton Memorial Library was completed.  The installation lasted more than a year and in phased sequence affected every area of the library building. Coping with the disruption tended to overshadow the significance of the system itself.

The building was constructed in 1968 without a fire sprinkler system, since one was not then required by building codes.  Adding two more floors to the building under today's codes made adding such a system mandatory.

A fire sprinkler system can be a double-edge sword in a library building.  Fire will affect library collections in ways that cannot be repaired.  On the other hand, errant sprinkler systems have been known to flood libraries by mistake, requiring costly salvage and restoration efforts. These events are rare, but documented nonetheless.  Generally, the proper installation of appropriate fire suppression systems is supported by preservationists in libraries since, in the end, a wet book would be preferable to a burnt one.  Importantly, fire sprinkler systems are mainly intended to protect people, especially in multi-story buildings where above 75 feet or so firefighters would have limited ability to provide adequate hose streams to, or rescue from, a raging fire.

The architects and project managers for the H-TML addition consulted with the library in addressing the requirements for a fire sprinkler system during the schematic design phase of the project before the construction began.  As a result the system for the Howard-Tilton building employs a combination of two sprinkler types: (1) a wet (water-based) system as the norm for most areas of the building and (2) a preaction system for the areas of the building that hold rare collections. Preaction systems also employ water but do not retain water in their pipes, thereby reducing any chance for leakage over especially high value collections.

In either type the system operates in an isolated fashion, i.e., a triggered heat sensor would set off only the closest individual sprinkler head, rather than multiple heads or the system as a whole.

There were other considerations with fire sprinkler systems beyond basic type and these included method of fire detection and system component variations.  These were addressed in the construction design as well. For more information about fire suppression systems see this report from the Northeast Document Conservation Center.

A need for first responders to have quick access to controls for the system factored in the design of a large mechanical control area now located on the first floor of the building adjacent to the fire lane between the library and Dixon Hall next door. Most of the library's new main mechanical systems and electrical central plant are now located on the 5th floor far above.

The sprinkler installation involved laying out pipelines with connecting sprinkler heads above the ceiling throughout the building, with sprinkler heads eventually poking through the ceiling at 8-foot intervals.  The installation began in the northeast quadrant of the 4th floor in February 2014 and was often delayed by differences between actual conditions above the ceilings and the pipe, duct, and conduit locations shown in the original 1967 schematic drawings for the building.

The impact of the sprinkler work often left large areas of the book stacks covered with plastic sheeting for long periods while disrupting access to offices, classrooms, and faculty carrels.  Early on, the library developed a retrieval system to help library users get books from covered areas.  During research-intensive periods in semesters when the installation progressed to the 3rd and then the 2nd floor the library set up a mobile Construction Concierge desk, from which staff or student workers provided onsite assistance . 

A difficult challenge for the sprinkler subcontractor came this past winter when crews needed to be divided between the work required on the new upper floors and the equally time-sensitive work required to rebuild the ceilings in the 1st floor elevator lobby and adjacent Learning Commons.  The final section of the system was completed on July 8 in the southwest quadrant of the 2nd floor.  

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