Fire sprinkler systems are easy for most to take for granted. But have you ever noticed the wide variety of fire sprinkler heads that you see in the commercial, retail, and residential spaces you visit?
Though they may seem the same to you, fire sprinkler heads come in different shapes and sizes, and these differences are not purely looks. Understanding how and why sprinkler heads are different is an important step before selecting a new or replacement fire sprinkler system for your building.
The Basics: Sprinkler Head Common Components
There are four main types of fire sprinkler heads on the market.
But, before diving into the descriptions of those, it’s helpful to understand the basic components common to all sprinkler heads and how they work:
- Sealing Assembly: also known as the “plug,” the sealing assembly on a fire sprinkler head helps prevent water from seeping out and escaping.
- Heat-sensitive element: all sprinkler heads have a heat-sensitive element that plays the primary role in activating the fire sprinkler system. In some sprinkler heads, a glass bulb is used, while in others, a fusible metal link is used.
- Glass bulbs: the glass bulbs used in some fire sprinkler heads act as a plug holding back the water in the system. The bulbs typically contain a glycerin-based liquid.
As the air around the sprinkler head reaches the target temperature – usually 155F or 200F – the glycerin-based liquid expands. Once the target temp is reached, the liquid expands enough to burst the glass bulb. With the bulb out of the way, water begins to escape from the sprinkler head, flowing toward the sprinkler head deflector (discussed momentarily). - Fusible link: sprinkler heads using a fusible link have metal filaments that are secured to the sprinkler with a heat-sensitive alloy. The alloy will melt as the temperature rises and, when the temperature reaches its target, it will melt away sufficiently to allow the metal filament to fall and activate the fire sprinkler, sending water towards the deflector.
- Glass bulbs: the glass bulbs used in some fire sprinkler heads act as a plug holding back the water in the system. The bulbs typically contain a glycerin-based liquid.
Glass bulbs and fusible links can be designed to respond to different temperatures. Thus, the heat-sensitive element chosen for a sprinkler head will depend on the needs and environment of the facility it is protecting.
- Deflectors: sprinkler head deflectors are the metal plates that direct the flowing water in the direction it needs to go. When water is released from the sprinkler head at activation, the stream hits the deflector and sprays outward.
Deflectors do vary depending on the type of sprinkler head because each type of head needs to disperse water in different directions. The deflectors for each sprinkler head will be discussed in further detail below. - Frame: the frame is the metal casing that surrounds/holds the heat-sensitive element, sealing assembly, and deflector.
- Fire sprinkler escutcheon: though not present with all fire sprinklers, the fire sprinkler escutcheon is a common addition to many pendant sprinkler heads.
Sometimes confused with caps, the escutcheon is a ring used with fire sprinkler pendants to cover the hole in the ceiling that had to be cut to allow the sprinkler head through.
The escutcheon does not cover over the sprinkler head, but fits around it, filling the gaps between the sprinkler head and the ceiling to give it a more finished and aesthetically pleasing appearance. The escutcheon also plays an important role in preventing heat from escaping and failing to activate the sprinkler head.
It is important only to get escutcheons that were made specifically for your fire sprinkler system, as they are designed to help with controlling the heat and activating the sprinkler accurately. Pairing the wrong escutcheon with a sprinkler head could prevent it from activating when needed.
4 Different Types of Fire Sprinkler Heads
Now that the basic components of all fire sprinkler heads have been discussed, here are the four main types that you will come across and a bit about what makes each one of them different:
- Fire Sprinkler Pendants: the pendant fire sprinkler head is the most common type that you will see. Pendant sprinkler heads descend from the ceiling with a convex, circular, gapped deflector plate on the bottom.
When the sprinkler heads activate, they send a stream of water downward onto their deflectors, which then disperse the water widely, side to side, throughout the room in a conical pattern.
Because the pendants extend from the ceiling, they provide the greatest amount of coverage of the space. There are many variations of the pendant, and it can be very effective in protecting a variety of buildings and spaces, from industrial buildings to daycares. - Concealed Pendant: when a pendant sprinkler head is recessed into the ceiling and concealed by a decorative cap that blends in flush with the ceiling, this is called a concealed pendant head. For those who are concerned about fire sprinkler pendants messing with their aesthetic, concealed pendants are an excellent option.
While it may seem like the decorative caps would hinder the sprinkler heads from operating, they are designed to fall away from the sprinkler head when the temperature reaches 20 degrees below the sprinkler system activation temperature. The plate will no longer be in the way if and when the temperatures are high enough to activate the system. - Upright Sprinkler Heads: upright sprinkler heads are pretty much what they sound like – sprinkler heads that point upward toward the ceiling with a circular, concave deflector plate on top (think umbrella).
Rather than descending through the ceiling, these sprinkler heads are usually mounted on pipes just below the ceiling. When activated, the water shoots up out of the pipe, hits the deflector, and is sent out and down in a dome-shaped pattern.
Upright sprinkler heads are efficient at dispersing water between obstructions. Thus, they are frequently used for rooms that are inaccessible, such as mechanical rooms, and in warehouses and industrial spaces. They are also often applied in structures with open ceilings.
An additional benefit to upright sprinkler heads is that since the deflector covers over the sprinkler head, it also protects it from debris and ice collecting. - Sidewall Sprinkler Heads: sidewall sprinkler heads protrude horizontally out of the wall parallel to the floor, rather than descending from the ceiling or mounted on a pipe pointing upward. Sidewall sprinklers are ideal for small spaces, such as hallways, spaces with obstructions, and/or where ceiling piping is not available.
The sidewall sprinkler head has a solid, rectangular, or semi-circular deflector plate that helps to disperse the water away from the ceilings and down and out in a crescent-shaped spray, directly towards the open space it is protecting.
While the above are the four main types of fire sprinkler heads on the market, there is still a wide variety to be found within each type, and there are also other types of sprinkler heads for unique applications.
What Fire Sprinkler Heads Does Your Facility Need?
While there are certainly elements of aesthetic appeal that play a role in choosing the fire sprinkler heads used in your building, you must remember that each type of sprinkler head is designed to fulfill slightly different purposes and meet different needs. Some will activate faster than others, some will be much more efficient at suppressing a fire in a room full of obstructions, etc.
Before you choose the fire sprinkler system for your new building or renovation project, you need to understand the specific functions that each type of sprinkler head plays and know what your unique space will require for efficient fire protection.
Don’t be overwhelmed by your options. The experts at Koorsen Fire & Security can help walk you through your options and can help identify the unique needs that your facility has. Give Koorsen a call today to get started.
