Know the key listed accessories in a listed sprinkler assembly
The fire protection world loves the word “assembly.” There are fire sprinkler support assemblies, drain assemblies, floor control valve assemblies, seismic separation assemblies, and more. One term—fire sprinkler assembly—is particularly important for understanding fire sprinklers and their necessary accessories.
This blog aims to explain the term, usually expressed as “sprinkler assembly” or “listed sprinkler assembly” in National Fire Protection Association (NFPA) standards and sprinkler manufacturers’ documents.
It’s a crucial concept that reflects the basics of a fire sprinkler’s design. Just as importantly, it determines which accessories a sprinkler can use to ensure it works right and doesn’t run afoul of codes and standards.
Read on to learn:
- What is a sprinkler assembly?
- The importance of the “listed” sprinkler assembly
- A summary of listed sprinkler assembly accessories
What is a sprinkler assembly?
Surprisingly, NFPA 13: Standard for the Installation of Sprinkler Systems doesn’t have an explicit definition for “sprinkler assembly” in its definitions chapter, though it uses this term in other sections of the standard. In contrast, the US Department of Housing and Urban Development (HUD) has a somewhat imprecise definition in its National Standards for the Inspection of Real Estate (NSPIRE), essentially just describing a sprinkler:
Part of the fire protection (sprinkler) system that discharges water when activated once reaching a certain (predetermined) temperature.
This still isn’t perfectly clear, so we’ll suggest a simpler definition: the sprinkler assembly is the essential physical components of an individual fire sprinkler head that make it work—ensure it activates and sprays water correctly to meet its design objectives.
Helpfully, Tyco shows what it considers the sprinkler assembly in diagrams within its data sheets. The illustration lists various parts, including the sprinkler’s frame, deflector, compression screw, link assembly, and more.
Here is the sprinkler assembly diagram for a Tyco TY9226 Early Suppression, Fast Response (ESFR) sprinkler:
These parts—everything from the link assembly that melts and falls away at a specific temperature to the shape of the deflector—are carefully designed to ensure the sprinkler does its intended job in particular applications.
The importance of the “listed” sprinkler assembly
All fire sprinkler head assemblies made by reputable manufacturers are “listed” by default because all of these fire sprinklers are listed. In NFPA terms, “listed” indicates any major certification verified by a testing laboratory that meets recognized standards for function and reliability. UL Listed and FM Approved are two significant listings in the fire protection world.
So, the Tyco ESFR sprinkler shown above is a listed sprinkler with a listed sprinkler assembly. However, additional sprinkler accessories on different sprinkler types can also be part of the assembly. And a listed sprinkler assembly means all these parts are tested and designed to work together.
The additional parts that may be part of a listed assembly for specific sprinklers include:
1. Cover plates that hide concealed sprinklers must fit perfectly and be the appropriate activation temperature to ensure they fall away and expose the sprinkler properly during a fire:
From the 2025 edition of NFPA 13
7.2.6.3 Cover plates used with concealed sprinklers shall be part of the listed sprinkler assembly.
NFPA 13 explains why:
The fusible elements holding the cover plate are designed to operate prior to the activation of the sprinkler’s thermal element. The cover plate is included as part of the listed sprinkler assembly. […]
If the cover plate is missing, the possibility exists that the concealed sprinkler and cup are not installed at the required elevation with the ceiling to achieve proper water distribution. In some cases, improperly installed concealed sprinklers have discharged above the ceiling, preventing water from reaching the fire.
This diagram of a Tyco TY3531 concealed sprinkler shows its listed “sprinkler/support cup assembly,” including the cover plate:
2. Recessed and flush escutcheons that surround sprinklers must also be listed to ensure that they fit, that the sprinkler stays in place relative to the escutcheon and wall or ceiling, and that nothing blocks the sprinkler’s spray pattern or operation.
From the 2025 edition of NFPA 13
7.2.6.2* Escutcheons used with recessed or flush-type sprinklers shall be part of a listed sprinkler assembly.
Here is a diagram of the sprinkler assembly for a Tyco TY3281 RAVEN Flush Institutional Pendent Sprinkler:
NFPA further explains:
Components for escutcheon plates, including cover plates, if used, are integral to proper sprinkler performance. The listing of these components ensures that the sprinkler, escutcheon, and cover plate combination will operate as intended and not adversely affect the discharge pattern of the sprinkler. […]
Instances have occurred in which the dimensions of a recessed escutcheon that was not investigated or listed with a sprinkler were such that the deflector was not clear of the escutcheon, which seriously impaired the spray pattern.
Note: NFPA 13’s definition of a flush-type sprinkler and escutcheon differs from the “flush” installation style and escutcheons that some manufacturers occasionally refer to when describing their equipment. You can read about this distinction in our previous blog: “Flush” vs. Flush Sprinkler Escutcheons: What Must Be Listed?
However, here’s a summary: NFPA 13 and its listed flush escutcheon requirement explicitly refer to sprinklers that are mostly hidden in a wall or ceiling. Examples include tamper-resistant institutional sprinklers and these Senju flush sprinklers.
Here’s a quick visual guide to which types of sprinklers and escutcheons must be listed and which don’t need to be listed:
3. What about head guards?
Head guards, also called sprinkler guards or sprinkler cages, protect sprinklers from damage and accidental activation in places where they are likely to take a hit.
NFPA 13 mandates using guards in these settings but, technically, does not indicate they “shall be part of a listed sprinkler assembly”—instead, it just says guards must be listed:
16.2.6 Sprinklers subject to mechanical injury shall be protected with listed guards.
NFPA 13 elaborates on the reason, and it’s similar to the rationale for covers and escutcheons:
Guards, by their basic design, have the potential to disrupt the intended sprinkler spray patterns. Listed guards are evaluated with specific sprinklers to verify that the disruption does not affect the performance of the sprinkler.
Nevertheless, NFPA’s language and manufacturers’ data sheets do not indicate guards are part of the sprinkler assembly. There may be an exception, however. Some sprinklers are made and shipped with preinstalled guards.
For example, some of Viking’s intermediate in-rack sprinklers used in storage facilities, such as the VK550, can be ordered with preinstalled guards and water shields. These parts are listed among the “building materials” of these sprinklers, so they could be considered part of the assembly.
Note: While NFPA 13 requires listed guards placed on sprinklers in places where they are “subject to mechanical injury,” the sprinkler manufacturers do not make listed guards for all their sprinklers. In addition, most heavy-duty head guards are unlisted and may be needed to handle harder hits. Individuals looking to install unlisted guards in these scenarios should check with their authority having jurisdiction (AHJ) for approval.
Get the right listed sprinklers and accessories!
Remember, every sprinkler has an assembly and must be listed; sprinklers are designed and tested to standards for use in a specific application. System designers outline which sprinklers meet various individual requirements when they design a sprinkler system.
However, it’s also important for building owners, maintenance contractors, and others to know which additional parts must be listed as part of a sprinkler’s assembly—in case these items get damaged or go missing and need replacement.
To summarize:
- Cover plates for concealed sprinklers must always be a part of the listed sprinkler assembly. Manufacturers’ data sheets, QRFS product pages, and QRFS’s QuickFinder can specify which covers go with which concealed sprinklers.
- Recessed and flush escutcheons used with recessed and flush sprinklers must also be a listed part of the sprinkler assembly. Again, the manufacturers make these components to fit specific sprinklers and outline which ones match sprinklers, such as this Senju D2 recessed escutcheon. However, one escutcheon type that is sometimes called flush—aka “standard” or “flat”—does not need to be listed. (Refer to the image above.)
- Head guards may not be technically part of the sprinkler assembly, but listed guards are tested to ensure they fit and don’t block the spray pattern or sprinkler operation. Unlisted guards may work in certain scenarios if the authority having jurisdiction reviews and approves them.
Know your sprinklers and their crucial accessories!
Again, you can consult the manufacturer’s data sheet to see the required accessories for a sprinkler, see matching models on QRFS product pages, or use our QuickFinder to determine the right combo using the sprinkler identification number (SIN).
Still have questions and need parts? Contact us at 888-361-6662 or support@qrfs.com!
Top image sources: Reliable Sprinkler via NFPA 13 and Tyco.
This blog was originally posted at blog.qrfs.com. If this article helped you, check us out on Twitter @QuickResponseFS.