Visual Inspection of Sprinklers
NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems provides the criteria for the routine activities that must be conducted to ensure that water-based fire protection systems, such as automatic sprinklers systems, can be relied upon in the event of a fire. These activities range from simple visual confirmation of some things such as valve position and room or water tank temperature on a more frequent basis, to much more complex activities such as full flow tests and internal assessments at longer intervals.
This blog will focus on the requirements for visual inspection of the sprinklers themselves. Check here for more information on the different types of sprinklers.
One of the required activities is to perform an annual visual inspection of the sprinklers themselves. An annual frequency is defined as occurring once per year with a minimum of 9 months and a maximum of 15 months between inspections. See this blog more information on NFPA 25 ITM frequencies.
From the floor
A key specification in the standard is that these visual inspection of sprinklers are intended to be conducted from the floor level. This means that typically there should be no special equipment needed for these routine inspections such as ladders or lifts. To further support this concept, NFPA 25 clearly states that sprinklers located in concealed spaces such as above suspended ceilings do not require inspection.
It is often asked if the requirements of NFPA 25 for sprinkler inspections only require a certain percentage of sprinklers to be included as part of the inspection. There is no allowance in the standard that indicates any sprinklers are permitted to be skipped during an inspection, other than those in concealed spaces as referenced above and for those installed in areas that are inaccessible for safety considerations due to process operations, the latter of which must be inspected during each scheduled shut down. The owner or their designated representative is responsible for providing access to sprinklers at the time of the inspection. See this blog for more information the owner’s responsibilities related to ITM. If certain sprinklers cannot be accessed for inspection it is common to note that on inspection reports.
What is being inspected?
The following are items that NFPA 25 includes as part of the visual inspection of sprinklers.
- Corrosion detrimental to sprinkler performance
- Physical damage
- Loss of fluid in the glass bulb heat-responsive element
- Loading detrimental to sprinkler performance
- Paint other than that applied by the sprinkler manufacturer
- Sprinklers installed in the incorrect orientation
- Minimum clearance to storage is maintained
The conditions in this list can have a detrimental effect on the performance of sprinklers by adversely impacting water distribution patterns, insulating thermal elements which could delay operation, or otherwise rendering the sprinkler inoperable or ineffectual.
The visual inspection does not include any sort of verification of the design or layout of the sprinkler system. This is true of all of the ITM activities specified by NFPA25. If NFPA 13 needs to be referenced to cite an issue then it is likely outside the scope of inspection activities of NFPA 25. Some inspectors might provide items related to the design of a system if they are noticed as a separate report. It is the responsibility of the owner to have a design evaluation performed if changes have been made.
Sprinklers that are leaking or that have been damaged must be replaced without testing. Dissolved minerals and other residues in the water can solidify as the sprinkler leaks, hampering the operation of the sprinkler by changing internal clearances or acting like an adhesive, preventing parts from moving as intended. Annex material in NFPA 25 makes a distinction between “spraying or running” water and “dripping” water. The sprinkler could be damaged and might not activate as it is intended to. Either way, this condition would require action because the functionality of the device is in question.
Corrosion detrimental to sprinkler performance
Corrosion found on the seat, or built up on the deflector that could affect the spray pattern, or a buildup on the operating elements that could affect the operation can have a detrimental effect on the performance of the sprinkler. Lightly loaded sprinklers or sprinklers having limited corrosion that does not impact the water distribution characteristics can continue to be used if the samples are selected for testing in accordance NFPA 25 based on worst-case conditions and if the samples successfully pass the tests. Surface discoloration that does not impact the performance of the sprinkler should not warrant replacement or testing.
Figure 1: Corroded Sprinkler (Courtesy of Wiginton Fire Systems)
Damaged deflectors should not be overlooked, although they can be difficult to detect from floor level. What might appear to be only slight damage to the deflector can have a drastic impact on the distribution of the spray pattern and the density of the water that is delivered.
Figure 2: Damaged Sprinkler Deflector (Courtesy of Wiginton Fire Systems)
Loading detrimental to sprinkler performance
Any loading used to require replacement however in recent editions the criteria for sprinkler replacement depend on whether the corrosion or loading is detrimental to sprinkler performance. This introduces a certain level of subjectivity into the inspection of sprinklers and further explains the necessity of those conducting the inspection to be qualified as defined in NFPA 25. Sprinklers that upon inspection show signs that they will not operate correctly are required to be replaced. However, those with light loading can be cleaned with a vacuum or a blast of compressed air.
Figure 3: Close-Up of Loaded Sprinkler (Courtesy of Wiginton Fire Systems)
Paint other than that applied by the sprinkler manufacturer
Sprinkler must be free of paint other than that applied by the manufacturer. Painted sprinklers are never permitted to be cleaned and/or reinstalled, because the potential of damaging the assembly is too great. A “light” overspray or loading can be tolerated when a representative sample is tested to verify that the sprinklers will operate as intended
Figure 4: Painted Sprinkler (Courtesy of Josh Elvove)
Sprinklers installed in the incorrect orientation
Sprinklers installed in the incorrect orientation such as an upright sprinkler installed in the pendent position will not develop an effective spray pattern. Where this happens, the situation must be corrected by repositioning the branch line, drop, or sprig, or the sprinkler must be replaced. While this is not always easy to tell from floor level, where it is observed it must be corrected.
Figure 5a: Upright Sprinkler Incorrectly Installed in the Pendent Position
Figure 5b: Pendent Sprinkler Incorrectly Installed in the Upright Position
Minimum clearance to storage is maintained
Obstructions to sprinkler distribution patterns, such as storage that is too close to sprinkler deflectors, can hamper the effectiveness of sprinklers. Obstructions that are closer than 18 in. (457 mm) below the sprinkler have a greater impact on distribution patterns than do obstructions located further away. These are easy to visually spot as opposed to many of the other obstruction distances specified by NFPA 13 so they are the only ones referenced by NFPA 25.
Figure 6 Typical Obstruction: Storage
There is much more that goes into a complete inspection of a sprinkler system than just the visual inspection of sprinklers. NFPA 25 should be referenced in full as it applies to a specific system. Sprinklers themselves should be visually inspected at an annual frequency for the items listed in this blog.