FX103 SERIES | SITE VISITS FOR INSPECTORS & INSURERS
How do you inspect for sprinkler obstructions?
HOW DO WE INSPECT FOR OBSTRUCTIONS?
Today we’re continuing on our inspection process for an existing sprinkler system from the perspective of an insurance carrier. How do we inspect for sprinkler obstructions, from our standpoint?
Obstructions from the construction elements are usually identified and taken into consideration in the design and acceptance phase for a project. Not always the case, but most obstructions are designed, installed, and inspected against at that time. We can still seek out these issues, but our hope is that most of these have long since been addressed.
Here, we’re really looking for changes that have occurred since the design and acceptance of the system. What has changed that would negatively impact the system in fighting a fire?
Obstructions at the ceiling level can usually be seen from the ground. Has anything been changed or installed that impacts sprinkler distribution? Lights? Mechanical Units? Fans? False Ceilings?
Obstructions can and are often also related to the storage of goods. There needs to be some space underneath the sprinkler to properly develop its water distribution pattern. If storage is located too close to the sprinkler, then it may prevent water to reach other areas within the room.
Such obstruction can be found in offices, with people placing cardboxes or files on top of storage cabinets.
This does not apply when a cabinet is located along the wall. You won’t properly protect the goods that are stored too high, but this does not present an obstruction to the water discharge.
A forgotten possible obstruction is one coming from overhead doors. When the door is closed, there is no obstruction to the ceiling sprinklers. But when the door is open, that is another story.
SPRINKLER INSTALL OBSTRUCTIONS
Other obstructions may be presented by the sprinkler installation itself.
Remember that upright sprinklers should be installed with the frame arms parallel to the branch line.
In addition to the branch line beneath the sprinkler causing problems, the frame arms could create disruption to the water distribution.
Aligning the frame arms with the branch line minimizes the number of obstructions in the water spray pattern. The installation rule for frame arms applies only to upright sprinklers, not pendent or sidewall.
Hangers should not be located too close to upright sprinklers. Again, this is to avoid a possible obstruction to the water discharge from the sprinkler by the hanger. A minimum safe distance of 3 in. (76 mm) should be maintained. Since pendent sprinklers are not affected by the hangers, this rule also only applies to sprinklers installed in the upright position.
The pipe (branch line) on which the sprinkler is installed is not considered a major obstruction, unless the piping is 3 in. (80 mm) or larger. Upright sprinklers on large branch lines or mains should be placed on sprigs to be offset from the branch line to eliminate the obstruction that is created directly below the sprinkler.
The elevation of the sprinkler minimizes problems that can occur when a fire is located directly below a sprinkler or directly under the branch line between 2 sprinklers.
The obstruction can prevent the discharge from reaching the fire and can also eliminate dead-air spots that might delay sprinkler actuation, such as when an upright sprinkler is located directly on a 6 in. pipe.
From an insurer standpoint, that’s an overview of how I look at obstructions when doing a walkthrough. Do the sprinklers have an opportunity to develop their spray pattern? Are there blockages in the way that would prevent them from suppressing a fire?
We want to be sure the system isn’t impaired in a way that would negatively affect the building or its occupants.
I’m Franck Orset, this is MeyerFire University.
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