Building owners will periodically hire painters to spruce up their interiors. But one common problem with painters is they sometimes paint over the concealed sprinkler cover plates in the ceiling. The reason is that most painters do not understand the
function of the cover plate. The application of paint is detrimental to the normal operation of the sprinkler assembly and could act like a glue and significantly delay the release of water from the sprinkler system. That is
why NFPA 13, Standard for the Installation of Sprinkler Systems prohibits painting of the covers by anyone other than the manufacturer. Other problems commonly found with installed sprinkler systems, include damaged, missing,
and improper fitting cover plates. Here is what you need to know regarding replacement of problematic cover plates, which will help assure your customer’s sprinkler system will work as intended.
Why Are Concealed Sprinklers Installed?
A concealed sprinkler assembly consists of the cover plate and a recessed pendant sprinkler with a support assembly to accommodate the cover plate. Concealed sprinklers are very inconspicuous. When looking at the ceiling, the only thing that is exposed
is the small flat cover plate, most often the same color as the ceiling.
These decorative sprinkler assemblies are installed in hotel lobbies, office buildings, churches, and restaurants where an architect or building owner wants to have a flush-finished look. A cover plate fully conceals the sprinkler in the ceiling, which
makes them aesthetically pleasing. They are installed in both drywall ceilings and drop ceiling tiles. The cover plates not only provide a finished look, they protect the sprinkler from accidental contact or intentional tampering and
activation.
How Concealed Sprinklers Work
Similar to sprinklers, the cover plate is heat sensitive. Typically, the cover plate is soldered to the retainer piece at three points. When exposed to a fire, the heat will melt the solder and the cover plate drops out. Once the cover plate is gone the
pendant sprinkler is exposed, which allows the sprinkler to be heat actuated and water flow to occur. The temperature-sensitive solder in the cover plate melts about 15°F–35°F lower than the sprinkler (depends on temperature rating
of sprinkler). Concealed sprinkler assemblies are only permitted to be installed in wet pipe sprinkler systems.
Problems with Painting, Caulking, and Gluing
In addition to the prohibition on painting, the use of caulking or any type of glue is prohibited when installing sprinkler cover plates. Painting the cover plate can retard the thermal response of the sprinkler. Caulk and glue do not react to temperature
the same as the manufacture’s solder and could cause a delayed response or worse—the sprinkler assembly could become inoperative. Wherever a cover plate has been painted by anyone other than the sprinkler manufacturer, the cover plate
is required to be replaced. Similarly, if caulk or glue is identified during an inspection, the cover plate is replaced.
Replacement Cover Plates
Cover plates are used to cover the annular space around a sprinkler. A missing cover plate will permit heat to escape through the gap, delaying the actuation of the sprinkler. The gap also allows smoke to vent from the protected space, which could delay
the smoke detection system from providing an early warning for occupant evacuation. Since a cover plate is part of the listed sprinkler assembly, a missing cover plate must be replaced. Immediate replacement of missing cover plates
is essential for life safety reasons.
Damaged or improperly fitting cover plates will either drop out too early or cause a delay in operation. Both conditions impact the safety of building occupants in the event of a fire. That is why regular inspections of concealed sprinklers are essential.
Problem cover plates can be identified during an inspection and replaced before a fire occurs.
Ordering Replacements
Each concealed sprinkler model has a specific cover plate that matches the sprinkler assembly. Cover plates can vary slightly or drastically in circumference, operating temperature, and method of attachment. So it is important to remember that cover plates
are manufactured and listed, as part of the concealed fire sprinkler assembly, and each one is intended for a specific model sprinkler. In order to get the right replacement cover plate, it is essential to find the Sprinkler Identification
Number (SIN). The SIN is alpha numerical and is located on a label on the cover plate. The SIN helps you identify the manufacturer brand and model number. This information is critical for ordering replacements.
The work on fire sprinkler systems should only be done by qualified sprinkler fitters (most states require licensed sprinkler fitters). Replacing damaged, missing, and improperly fitting cover plates, along with replacing any other necessary parts found
to be deficient, will help ensure the sprinkler system is operational and up to code, once the replacement work is completed.
Mark Conroy is an engineer in our Boston office and a member of several NFPA Technical Committees.