A unique sprinkler identification number (SIN) often indicates whether a specific fire sprinkler is a concealed or exposed model. But there are exceptions!
Fire sprinklers are easy to identify and understand via their sprinkler identification numbers (SINs). This four-to-seven-digit alphanumeric code shown on a sprinkler’s deflector tells you almost everything you need to know about it.
The SIN typically identifies all the key characteristics, including orientation, K-factor response type, and more—usually, everything except finish and activation temperature. A SIN commonly specifies whether a sprinkler is an exposed or concealed model, the latter hidden behind a cover plate. But there are models where one SIN and sprinkler can be installed either concealed or exposed—and this blog explains what they are and why.
Read on to learn about:
- The different design of many concealed sprinklers and the importance of the “sprinkler assembly”
- Fire sprinkler models can be installed exposed or concealed
- The simple ways to identify dual-application models
The different design of many concealed sprinklers and the importance of the “sprinkler assembly”
Usually, concealed pendent and sidewall sprinklers have a significantly different design than exposed versions.
An exposed sprinkler always has a rigid frame that projects from a visible supply pipe and fitting or from a finished ceiling or wall—in the latter cases, escutcheons surround the sprinkler and cover the gap in the surface.
Since the sprinkler is exposed, its heat-sensitive glass bulb or fusible link simply reacts to the fire by breaking or melting, quickly releasing the pressurized water that hits the deflector without any extra steps.
In contrast, concealed sprinklers hide within walls or ceilings behind cover plates. These sprinklers activate in a two-step process:
- The covers react to the fire first, usually at a lower activation temperature than the sprinkler. The heat from the fire causes the solder on a fusible link in the cover plate to melt, and the cover drops away.
- From there, the exposed fire sprinkler deploys.
All concealed models have a cup or otherwise integrated circular design that allows the attachment of a cover plate.
One way most concealed models differ from exposed sprinklers—and any sprinklers that can be installed exposed or concealed—is that they don’t have a completely rigid design. A concealed sprinkler’s deflector that shapes the water’s spray pattern often drops from the ceiling on rails or projects from the wall after the cover falls away.
Some sprinkler deflectors automatically deploy from the surface once the cover is gone, while others, like this Viking sidewall, may deploy the deflector when the sprinkler itself activates. In every case, the now-exposed deflector sticks out from the surface and channels the pressurized water in its appropriate pattern.
Regardless of the specific design, most concealed models have deflectors held tighter against the rest of the sprinkler until they deploy. This design enables using flat cover plates that sit flush with a ceiling or wall.
This video from FireAlarmDude5967 shows how a concealed sprinkler works, including an activation demonstration at 1:09:
So, the key differences between exposed and concealed sprinklers are:
- All concealed sprinklers have an extra step; the cover plate must activate and fall away before the sprinkler does.
- All concealed sprinklers and their cover plates activate as a complete “listed sprinkler assembly.” A specific, listed (safety-tested and approved) cover is designed to work with particular sprinklers that have a support cup, ensuring everything fits and works properly. You can read more about the sprinkler assembly here.
- Many—but not all—concealed models have deflectors that deploy outward from the surface after the cover falls away.
Fire sprinkler models that can be installed exposed or concealed
To cut to the chase, some SINs can be exposed or concealed sprinklers, and those models always have these characteristics:
- They all have a basic design that’s identical to non-concealed sprinklers. These sprinklers have a rigid frame where the deflector does not drop down or project outward once the cover plate falls away. The only difference in this design from the exposed versions is that these sprinklers have a preinstalled “support cup” allowing installers to attach a cover plate.
- Because of this rigid-frame design, the concealed sprinkler always projects from the wall or ceiling a bit and requires a domed cover plate—they can’t use a flat cover plate.
Here are some examples from major manufacturers:
Reliable has a number of sprinklers that have the same SIN yet can be installed exposed or concealed, including numerous heads in its Model F1Res Series Glass Bulb Residential Sprinkler line.
Within that series, the R3511, R3513, R3516, and R7618 pendents and R3531 horizontal sidewall can all be installed either wholly exposed (no escutcheon), with a standard (flat) escutcheon, recessed (with an F1 or F2 escutcheon), or as a “conical concealed” sprinkler with a domed CCP cover plate.
Thus, when you order one of these Reliable sprinklers that can be installed exposed, recessed, or conical concealed, you must specify whether you want the concealed version or not. Since the sprinkler identification numbers are identical, it’s relevant to drill deeper into Reliable’s exact “part number” or “short code.” (Unlike other manufacturers, Reliable has two of these identifiers for its sprinkler models; most manufacturers just have a part number.) Either code will work.
To get one of these codes, you’d consult one of Reliable’s price books—in the case of Model F1Res sprinklers, the residential price book. As you can see below in the example of an R3511 sprinkler, there are different short codes and part numbers for the concealed vs. non-concealed versions:
Another example is Tyco’s now-discontinued multipurpose version of the TY2234 LFII residential pendent sprinkler. One can still order older versions of this sprinkler as an exposed pendent with an escutcheon or a concealed pendent with a domed cover plate.
Again, both older versions of this sprinkler have the same SIN and basic design. However, the concealed version needs to be ordered with its preinstalled “support cup assembly” that surrounds the sprinkler and provides a place to attach the cover plate. Since both previous versions have the same SIN, people buying these sprinklers also need a different part number. (Learn more about Tyco part numbers here.)
That said, the multipurpose version of the TY2234 has been discontinued—at least, the exposed version that needs an escutcheon is no longer made, though it’s still for sale. Tyco has simplified things by making the new TY2234 SIN exclusively a concealed sprinkler with a domed cover plate, while the new exposed version of this head is now SIN TY2236, which uses Style 15 or Style 20 escutcheons.
Viking also currently makes some sprinklers that have almost the same SIN but can be installed either exposed or concealed. We say “almost” because the SIN technically has a letter at the end that distinguishes the different versions: the exposed sprinkler is the VK468, while the SIN VK468-D indicates the concealed version with a domed cover plate.
Again, the concealed version comes with a preinstalled support cup and has a different part number: 13637A-X (concealed) vs. 13637 (exposed).
The simple ways to identify these dual-application fire sprinkler models
Again, manufacturers assign sprinklers a unique sprinkler identification number (SIN) that usually reveals all the major characteristics (including concealed or exposed) except temperature and finish. However, some exceptions exist, including models that can serve as concealed or exposed models—as long as you order the right version.
There is a very simple visual test to determine what you have and may need:
- If the concealed sprinkler looks like a regular exposed sprinkler—it has a rigid frame—and the only difference is the presence of a support cup surrounding it, it may have the same SIN for two versions.
- Since these sprinklers have rigid frames and deflectors that don’t move to deploy, they stick out of a ceiling or wall a bit and require domed cover plates.
Of course, you can typically always know exactly what a sprinkler is, including different version and what accessories are required, by finding the SIN on the deflector and then looking at the specific sprinkler’s data sheet. The vital documents, present on manufacturers’ websites and QRFS product pages, have all the info you need.
If you need fire sprinklers or accessories, check out QRFS’s selection of heads, including concealed pendants and sidewalls, plus escutcheons, cover plates, and more.
If you have questions or need help ordering the right part, contact us at 888-361-6662 or support@qrfs.com.
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