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Author(s): Brian OConnor. Published on November 1, 2018.

In Compliance | NFPA 13

Back to basics: Sprinkler types & systems


When I was first learning about automatic sprinkler systems, I would invariably ask myself what my options were—in a given scenario, what was in my engineering toolbox to meet a particular protection challenge?

It’s useful to ask that question again, considering the organizational changes made to the 2019 edition of NFPA 13, Installation of Sprinkler Systems. A list of the different sprinkler types, sprinkler system types, and common uses for each, as grouped in Chapters 10–15 in NFPA 13, will help familiarize users with the layout of the new NFPA 13 and remind them of the available options and design considerations when working on projects.

Chapter 10: Standard pendent, upright, and sidewall spray sprinklers

Standard sprinklers are just that: the standard when it comes to installing sprinklers. They have a heat-activated element made of either a glass bulb or a fusible metal link that will activate and discharge water when heated to a designated temperature.

Chapter 11: Extended coverage upright, pendent, sidewall spray sprinkler

As the title suggests, these sprinklers have a larger, or extended, coverage area when they discharge. This can help save material and labor costs because you do not need to install as many sprinklers. The trade-off is that they might require a water supply with a higher pressure to discharge at the higher flow rate necessary to cover the larger area they were designed for.

Chapter 12: Residential sprinklers

Residential sprinklers are designed specifically for use in residential occupancies and are a type of fast response sprinkler. They are designed specifically to enhance survivability in the room of fire origin and discharge water higher on the wall than typical sprinklers. Another difference is that they utilize less water. Installing residential sprinklers instead of quick response standard spray and extended coverage sprinklers can reduce the water requirements by roughly 20 percent.

Chapter 13: Control mode specific application (CMSA) sprinklers

These are designed for applications such as storage occupancies. These designs, along with most other types of sprinklers, are intended to control the fire, not suppress it.

Chapter 14: Early suppression fast response (ESFR) sprinklers

These are designed for storage occupancies, similar to CMSA sprinklers. ESFR sprinklers are the only ones designed for fire suppression rather than control. These are designed to protect rack storage without the need for in-rack sprinkler protection. The ESFR concept is to apply a sufficient amount of water to the burning fuel during the early phases of a fire and penetrate the developing fire plume, achieving suppression.

Chapter 15: Special sprinklers

This covers several types of sprinklers and is a catch-all for sprinklers used in special applications: open sprinklers, dry sprinklers, and old style sprinklers.

Open sprinklers are used in deluge systems. They are not activated by individual thermal elements as previously discussed—instead, the system water supply is held back by a deluge valve that is automatically opened most often by activation of a heat detection system. This is meant to deliver a large amount of water over a specific area in a short amount of time. They are typically used for protection against high-hazard or rapidly spreading fires.

Dry sprinklers are used in areas where a wet pipe system wouldn’t work properly, such as areas where the sprinklers and piping are subject to near-freezing temperatures. This would commonly be a freezer or outdoor area.

Old style sprinklers are only permitted for special situations such as the protection of fur storage vaults. These sprinklers have a unique water distribution, where half the water is directed upwards and half is directed down. This typically allows these sprinklers to be installed in either the pendent or upright position.

In conclusion, with 13 orifice sizes, six temperature classifications, three sprinkler orientations, 10 deflector designs, and two response characteristics, there is a multitude of sprinkler types on the market. Add the type of sprinkler system to this mix, and picking the correct one can be tough. But with an informed inventory in your engineering toolbox, you can make the right choice.

BRIAN O'CONNOR is a fire protection engineer at NFPA.