Don’t Get Burned by Sprinkler System Freeze-Ups

January, 2012

If your parking structure is enclosed, if the ceiling is less than 24 inches above grade, if your structure is of Type III or Type IV construction more than 50 feet in height, or if your parking structure is immediately below or adjacent to a building used for another occupancy, chances are that it has a fire sprinkler system installed. And if you do, chances are good that it is a “dry system.”
Dry sprinkler systems enable protection from fire to be economically included into a parking structure by filling the exposed piping network with compressed air while the water is held back within a conditioned space to prevent freezing. Unlike their “wet system” counterparts installed in completely conditioned environments such as hotel, hospital and office buildings, dry systems require a little more attention.
Dry sprinkler systems make their own air, but a byproduct of the air makeup is condensation. And it is the accumulation of condensation that, if left in the system when winter temperatures start to arrive, can result in the system freezing up and potentially suffering a fracture.
The accumulation of condensation during warm weather does not put the system at great risk, and if the system has been properly prepared for prolonged freezing temperatures and is being monitored regularly, the depths of winter can also be a relatively maintenance-free period.
Trouble comes in the fall with unexpected successive freezing nights and slightly warmer days; in the winter, if the system has not been prepared; in climates with more mild winter temperatures but subject to the occasional freeze; or an unanticipated late-spring cold spell.
The goal as an owner or operator of a parking structure with an automatic sprinkler system is to make sure the dry system is “dry” and stays “dry” when the weather starts to change.
Dry systems are designed and installed in such a way as to channel accumulated moisture to accessible extraction points officially called auxiliary drains, but also known as condensation collectors or drum drips.
As a sprinkler system moves up and down the ramps through a parking structure, the opportunity exists for many low points; a drum drip should be installed at each of these locations. They usually are found in a corner or against a column at the end of a piece of pipe; typically about 2 feet in length, they are made using two 1-inch valves separated by a section of 2-inch pipe.
Moisture in the system will flow down to these extraction points, where it can be easily removed, without activating the dry system, by closing the upper valve and opening the lower valve to remove the accumulated condensation. The process of closing and opening the valves in opposition is continued until all water is removed.
While the process is simple, it is very important to follow the proper sequence and make sure that the two valves of the drum drip are not open at the same time or else the dry valve will trip, filling the system with water, sensing there is a fire to fight. It is important to realize that the condensation collector’s design configuration is set up to allow for moisture to be removed from the system without tripping the dry valve; it is not designed to accommodate the collection of an acceptable amount of moisture, because even the smallest amount of condensation in the drum drip can and will freeze, potentially causing a system fracture.
Drum drips are required to be marked with signage identifying them as an auxiliary drain. These collectors can be site-built by the installing contractor, or a number of manufacturers supply purpose-built units. Some of these manufactured units fulfill the basic requirements, while others offer more elaborate features such as lockouts to prevent vandalism, anti-trip designs to prevent the accidental discharge of water into the system, and water-sensing alarms to alert to the presence of moisture in the system.
As explained above, maintaining the system by monitoring and emptying accumulated moisture is a simple process that can be easily accomplished by existing staff with just a little training. Many of the manufactured drum drips actually have their operating instructions printed directly on them. Others are designed to prevent accidental tripping by untrained personnel. And a few have built-in moisture sensors to notify those responsible that the system requires maintenance attention.
As the weather starts to cool, a regularly scheduled monitoring program with a detailed parking structure plan identifying all auxiliary drain locations will be your best defense for preventing costly sprinkler system repair charges.
So remember, if you allow your sprinkler system to become out of sight – and out of mind – you will find yourself paying out of pocket and potentially end up out of profits.
Rich Pancoast, Marketing Director for AGF Manufacturing, can be reached at rpancoast@testandrain.com.
For more information regarding the requirements for installation of fire sprinkler systems in parking structures, please refer to the National Fire Protection Association (NFPA) standards: NFPA 88A Standard for Parking Structures (2011 Edition); NFPA 13 Standard for Installation of Sprinkler Systems (2010 Edition); NFPA Standard for Installation of Standpipe and Hose Systems (2010 Edition); NFPA 25 Standard for Inspection, Testing and Maintenance of Water-Based Fire Protection Systems (2011 Edition); along with other applicable Standards and Publications.
– Rich Pancost