The history of fire sprinkler systems and their problems
Fire sprinklers have evolved over the years to account for larger warehouse facilities
Since the first fire sprinkler system was deployed in the early 1800s and further refined over the next century, the aim was to protect buildings and their contents from the ravages of fire. The sprinkler system was nothing more than perforated piping with a hopper filled with water using gravity to feed the water through the piping. In the late 1800s, the automatic sprinkler head was developed, allowing piping to be filled with water and pressurized, only discharging water when a sprinkler was activated.
Early fire sprinkler systems were developed to protect commercial and industrial facilities by minimizing the damage caused by fire. It was more common to see multilevel facilities historically, but that gave way to taller single-level buildings as racking grew taller and material handling equipment rose to the challenge. Rising costs of real estate also have contributed to the desire to maximize square footage by increasing cubic footage of space.
In the 1970s, initial research was performed to determine how to protect commodities that were stored at a higher height in increasingly taller buildings. This led to the development of in-rack fire sprinkler protection, the need for specifically defined flue spaces within storage arrangements and a need for generally open shelving in storage racks to allow for distribution of water from the fire sprinkler spray pattern.
It also led to the development of a larger orifice fire sprinkler (17/32-inch orifice or 8.0 K-factor) that could supply more water through each individual fire sprinkler. This began a new era for designing fire sprinkler systems using hydraulic calculations. These calculations provided quantitative means and allowed for more accurate flow rates to be predicted with associated pressure losses due to friction, elevation and other factors. This research provided an acceptable method of protecting more commodities stored higher than ever before.
However, in-rack sprinklers resulted in significant cost to projects, additional care to maintain the systems and became prone to being damaged by human error. Additionally, in-rack sprinkler protection also limited the flexibility of the end user to modify what was being stored, how it was being stored and lacked mobility.
The next challenge came with the increasing volume of products using a higher percentage of plastic and continuing to store to greater heights. New research and technology pushed the envelope further from the 1970s and led to the development of the first early suppression, fast response fire sprinkler in the 1980s, which had an even larger orifice of ¾ inches (a K-factor of 14). This allowed for taller storage and, in some scenarios, also provided options for either eliminating the need for in-rack sprinkler protection or minimizing the amount of in-rack sprinklers needed to achieve adequate protection.
The initial ESFR sprinkler used the pendent position to take advantage of increased efficiency in water delivery as well as improved deflector shape and spray pattern. This pattern was not just a typical umbrella pattern, but also had a jet type spray directly beneath the sprinkler. These ESFR sprinklers could eliminate the need for in-rack fire sprinklers — lowering costs and minimizing potential for accidental discharge due to damage caused by human error.
However, these sprinklers present other challenges for successful implementation, such as strict adherence of sprinkler placement to minimize spray pattern disruptions due to obstructions and to optimize response time. In addition, flues spaces need to be maintained to allow heat from a fire to rise vertically as quickly as possible, while also minimizing horizontal flame spread.
The wave of ESFR research and innovation continued up through the 2000s, with continued full-scale testing for new storage arrangements, commodity types and heights, among other factors. The orifice sizes continued to increase with K-factors steadily rising nominally to 17, 22, 25 and now even a K34 with a 1¼-inch orifice that can be used for storage arrangements up to 50 feet tall in buildings up to 55 feet tall.