Contrary to popular belief, fire sprinklers do not react to smoke and are not triggered by fire detectors. Moreover, every fire sprinkler in a system will not all activate at the same time. In fact, most fire sprinklers solely react to high heat, and they will trigger once a certain heat threshold is met. This threshold, along with the type of sprinkler you need will be determined by NFPA 13 standards. Ultimately, you must consider your occupancy type and maximum combustible load to determine what sprinkler type you need.
The two types of triggers commonly found on fire sprinklers are glass bulb and fusible link. In a glass bulb sprinkler, a glycerin-based heat-sensitive liquid will expand and break the glass bulb in response to intense heat. Consequently the plug, or sealing assembly will be released and allow water to be discharged. Similarly, a fusible link is soldered to the sprinkler, which will melt when exposed to certain temperatures and will also release the sealing assembly. Afterwards, water will collide with a deflector, which allows the water to be spread evenly.
The clever design of fire sprinklers means that each fire sprinkler activates independently. As a result, the temperature threshold serves as a means to prevent accidental discharge. Additionally, we have increased water discharge per sprinkler due to higher water flow, and lower water damage to our property, since not all sprinklers activate at once.
The primary difference between standard and quick response sprinklers is the fast-response bulb or fusible link, which has a lower Response time index (RTI). If you are interested in learning more about how RTI is measured and calculated you can visit this article written by the NFPA. The lower thermal sensitivity of a quick response sprinkler head is caused by different designs in the trigger mechanism. For example, a quick response sprinkler will have a 3mm glass bulb in comparison to the standard 5mm bulb.
Fast response sprinklers have RTI of 50 or less, while standard response sprinklers have RTIs of 80 or more. Since quick response, residential and early suppression, fast response (ESFR) sprinklers all use similar triggers to react to fires more quickly, they are all considered fast-response sprinklers.
It is also quite helpful to know that standard response heads are generally cheaper than quick response heads and require less testing. To be specific, standard heads require testing / replacement 50 years after their initial installation compared to 20 years for a quick response head.
So, if quick response sprinklers always respond more quickly to a fire, what is the purpose of standard response heads in the first place? In short, standard response heads are less taxing on the system, so you are able to have more sprinklers operating at high efficiency. This means you can slow down the fire enough to give time for fire authorities to respond. These sort of sprinklers are recommended for extra hazards, storage sites, machine shops, etc., with the reason being that flash fire events would open too many sprinklers, thus overwhelming the available water supply. Owing to this, standard response sprinklers are able to suppress a fire more effectively where the combustible load is higher.
In comparison, quick response sprinkler heads are best used to protect life in residential or occupied spaces. After all, occupied spaces often have lower combustible loads and less hazards that will force many sprinklers to activate at once. Moreover, the earlier water is applied, the smaller the size of the resulting fire, giving the occupants more time to safely evacuate the building. For this reason, quick response sprinklers are used in offices, corridors, dormitories, hotels, and schools to quickly react to fires.
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ESFR sprinklers are designed for high piled storage facilities with the goal of suppressing a fire, rather than simply controlling it. They use up to 100 gallons of water per minute compared to the ~30 gallons in standard sprinklers. Due to this, they are completely impractical in a residential setting, where the water supply is a limiting factor. Also, this means that they can often require the installation of fire pumps to maintain water flow.
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There are many benefits to using ESFR sprinklers. Firstly, they can extinguish the fires of highly combustible and chemical materials, effectively limiting the overall property damage caused by the event. Additionally, when one head activates, it will limit the activation of the surrounding heads to maximize system water flow efficiency. Finally, they allow you to move away from in-rack sprinkler piping systems. Instead, ESFR sprinklers must be mounted on the ceiling. This results in lower material costs, and you have a lower chance of accidental activation due to an impact.
ESFR sprinklers are designed for directly suppressing fires, rather than simply slowing them down. Due to this difference, they are categorized differently than standard and quick response sprinklers. Make sure you understand your building’s hazards and occupancy type to find out what sprinkler offers the protection you need.
Are you interested in purchasing fire sprinkler heads for your system? Explore our stock of commercial pendent, upright, sidewall, and concealed fire sprinklers, or our residential fire sprinkler assortment and more.
