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.  

Friday, July 24, 2015

Library to Close Next Weekend (Aug. 1-2) for HVAC Testing

Project managers have set the weekend of August 1 and 2 as the date to begin the start-up, testing, and balancing of the new HVAC (heating, ventilating, and air conditioning) system within the library's lower floors. The start-up will likely begin that Friday evening, July 31, after the library’s normal hours and continue through that Sunday. During that period the library will be closed.

Testing and balancing components of the new HVAC system began last week and was limited to the upper 5th and 6th floors. The system is working well and the new upper floors are noticeably cooler than the lower ones still dependent on the ”temporary” blowers, towers, and tubes upon which the library has relied since the building was reopen in spring 2006 after Hurricane Katrina .

The closure is a precautionary measure that will allow testing and balancing the system on the lower floors to be done while the library is unoccupied. During the closure air quality in the building would be tested, although the existing duct on the lower floors has been sample-tested for dust and contaminants in recent years with no problems identified. Once the air flow from the new system is properly checked out, a switch to the new system will take place ASAP.

The new HVAC system is part of a new mechanical and electrical central plant that occupies about two-thirds of the floor space on the 5th floor, although the area is walled in and hidden from view.  To build these systems on an upper level instead of a ground floor or basement, mechanical/electrical chase spaces through the center core of the building were reconfigured for vertical duct work to feed from the top-down rather than from the basement-up. New vertical duct, electrical conduit, and pipe were tied into the existing lateral distribution systems. Stair and elevator emergency pressurization systems were adjusted to meet current building codes.  All the new mechanical and electrical equipment has greater capacity to provide service for the two new floors and the mechanical systems include high performance air filtering and temperature/humidity controls.

Extra systems were put in place to eliminate any noticeable noise or vibration in all directions outside the mechanical area.  All equipment using water or liquid rests on large stainless steel drip pans with drainage systems and equipped with sensors that will shut off units when dripping water or liquid in a pan is detected.  As an added precaution, the floor and lower walls of the entire mechanical area are coated with thick layers of epoxy that produce a seal like a swimming pool and the floor itself has drains.  

The 5th and 6th floor construction scope includes removing all the old hanging tube that serves as temporary air duct on floors 1-4 of the building and replacing all the lower floor windows and transoms displaced by the tubes. Also included would be any other related interior repairs. Outside, the contractor will remove all the towers, blower units, and temporary chilled water pipe behind the building and restore that area to pre-Katrina condition as well. This dismantling of the old HVAC system and related repairs is expected to be completed in August.