Author Amy Anderson
Did you know that I’m passionate about fire protection? Instead of proving it with stories recounting soakings by numerous fire hydrant, fire pump, and deluge system tests, I will share more about fire sprinklers! (Working on solidifying my fire sprinkler nerd status!)
Automatic fire sprinklers have an over 150-year history, with Henry S. Parmelee being credited with their invention in 1874. According to patent drawings, his early device, titled “Fire-Extinguishers,” appeared rather unconventional compared to a more recognizable form that developed within a few years.
Henry S. Parmelee’s 1874 Patent
NASA and Etsy (wait, that’s Esty) have longer histories than you may realize. The National Automatic Sprinkler Association (abbreviated NASA, of course!) marketed a sprinkler named “Esty” in the early 1900s. Although the classic fire sprinkler design developed rather quickly, there were no significant advancements for many more years.
An early 1900’s Esty Sprinkler (image from www.worthpoint.com/worthopedia/antique-vintage-fire-sprinkler-head-4576474011)
Increased fire hazards in manufacturing, storage, and building construction have driven, and continue to drive, improvements in sprinkler technology. These improvements were supported by full-scale fire testing and computer modeling of sprinkler system flows.
Until the 1970s, the largest sprinkler orifice size was 1/2-inch (K5.6). In the mid-to-late 1970s, the introduction of 17/32 inch orifice (K8.0) sprinklers marked a significant advancement, as the slightly larger diameter allowed for better water flow. Following this development, Extra-Large-Orifice (ELO or XLO) K11.2 sprinklers, a subset of which were known as large-drop sprinklers, were introduced. These K11.2 sprinklers required a larger thread size, 3/4-inch, compared to the standard 1/2-inch threads used by their smaller counterparts.
Approaching the end of the century, as warehouses increased in height, a common fire protection scheme involved ceiling sprinklers plus in-rack sprinklers, which are installed within the racks.
Warehouse racks with in-rack sprinklers
Dissatisfaction with in-rack sprinklers is commonly attributed to cost, limited flexibility for rack re-arrangement, and potential water damage from sprinklers being struck by lifts or pallet loads. In 1989, the demand for ceiling-only fire sprinkler protection was addressed with the introduction of the first Early Suppression, Fast Response (ESFR) sprinkler at K14.0. The benefit of ESFR protection is that it can protect high rack storage when installed only at the ceiling level, eliminating the need for in-rack sprinklers (albeit with various caveats). For reference, if water at 50 psi is supplied to an open K14 sprinkler, it will flow at a rate of 99 gallons per minute (gpm). The K-factors of sprinklers became as essential to their descriptions as temperature ratings or orientation (pendent, upright, or sidewall). Notably, Central, Gem, and Grinnell all produced K14 ESFR models named “ESFR-1.”
The Grinnell ESFR-1, the “O.G.” ESFR (from a Grinnell Technical Datasheet)
The next increase in sprinkler size emerged a decade later with the introduction of the K16.8 (“K17”). In the late 1990s and early 2000s, the K19.6, K22.4, K25.2, and K28 ESFR models were quickly developed, all belonging to the “storage sprinkler” category. K17s are the largest sprinklers with 3/4 inch threads. Sprinklers with K-factors ranging from 19.6 up to 28 feature 1-inch threads.
Eliminating in-rack sprinklers led to an increased need for fire pumps and water tanks, as the larger ESFR sprinklers require significant water pressure to operate effectively, and at such pressures, they flow a substantial amount of water. Often, public water systems could not supply the necessary pressure, creating a demand for additional fire protection equipment.
Giant Sprinklers. A K28 is not the largest sprinkler available. The biggest available sprinklers I’m aware of have a K-factor 34 (33.6). These fire protection giants required the next larger thread size, 1-¼ inch. TYCO’s Ultra K34, specially designed for cold storage applications, is so large, it could be mistaken for an over-scale model! Its sibling, the ESFR-34, is designed to protect warehouses up to 50 ft high without the need for in-rack sprinklers (with certain conditions). For reference, if a K34 sprinkler is supplied with 50 psi water pressure, it flows at a rate of 238 gpm. In comparison, a K14 sprinkler flows at 99 gpm, and a K5.6 at 40 gpm.
Two K5.6 sprinklers, each about 2 inches high, next to a scaled print of the impressive Ultra K34, which stands about 4-1/2 inches high
An Electronically Activated Sprinkler With Its Heat Detector, from TYCO’s EAS-1 Brochure
Smart Sprinklers. Smart devices are everywhere these days, so why not smart sprinklers? Traditionally, automatic sprinklers have been thermally activated. However, a new concept introduces electronic activation. A couple of electronic activation options currently exist, coming with or without a thermal activation option. Electronic activation integrates a fire detection system with a fire sprinkler system, aiming to activate a group of sprinklers over and around a fire more quickly than with thermal activation. This allows for rapid, targeted fire suppression at the earliest stages of a fire. Not only does that mean less fire damage, but the design scenario also means less water flow, thereby necessitating smaller fire pumps and potentially smaller water tanks or even no water tank!
From the early days of the K5.6 sprinkler to the newest K34 giants, developments in fire sprinkler technology answer evolving fire protection needs of increasingly complex and high-risk environments. Fire safety and protection reliability are critical in advancements in fire protection, while also balancing practical considerations such as cost and water usage. These measures aim to safeguard lives and properties from the devastating effects of fire.
Amy Anderson, PE, CFEI, has a Bachelor of Science in Chemical Engineering from Clemson University and is a licensed Professional Engineer in Fire Protection, as well as a Certified Fire and Explosion Investigator. Amy has over 20 years of engineering experience including property loss prevention engineering specializing in fire protection, chemical and pharmaceutical facilities. She has partnered with clients to identify, assess, avoid, and reduce risk at their commercial and industrial properties. Additionally, she has assisted with the development of building and fire protection specifications, reviewed plans and performed site visits. She has reviewed project documents for compliance with applicable standards – construction, fire protection, process, and combustible dust hazards. Amy is a member of the National Association of Fire Investigators, the Society of Fire Protection Engineers, the National Fire Protection Association and the American Institute of Chemical Engineers.
