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Residential Pendant Fire Sprinkler Heads – How do they Work?

TYPES OF PENDANT FIRE SPRINKLER HEADS

Two types of pendant fire sprinkler heads are currently available and work in different ways:

  • concealed residential pendant fire sprinkler heads
  • traditional pendant design fire sprinkler heads

Concealed fire sprinkler heads are more commonly installed in, and appropriate to, residential settings nowadays.

Comparing Pendant Sprinkler Heads

These two types of fire sprinkler head differ in a number of ways:

  • how the residential pendant firesprinkler heads work
  • how the residential pendant firesprinkler heads are designed
  • how the residential pendant firesprinkler heads are placed and their visibility

How Do Pendant Fire Sprinkler Heads Work?

Concealed Residential Fire Sprinkler Heads

Concealed residential pendant firesprinkler head

Concealed residential fire sprinkler heads are classified as ‘fast response’ heads, facilitated by the sprinkler system activating at an early point in the development of a fire.  In contrast to the pendant design, they are a two-stage device.

In the event of a fire reaching its operating point, the flat cover ceiling plate will fall from the device, allowing the deflector plate of the sprinkler head to drop below the ceiling level. As the temperature at ceiling level increases to 74 degrees Celsius, a bi-metal strip activates and releases the seal, enabling the full flow of water to be directed towards the fire.

Each fire sprinkler head is activated independently, maximizing pressure, flow and delivery of water to the fire and avoiding water damage to areas that are not alight.

 

 

Traditional Pendant Fire Sprinkler Heads

Exposed residential firesprinkler head

Unlike concealed residential fire sprinkler heads, the traditional pendant design heads are a single-stage device, not concealed and project below the level of the ceiling, allowing water to travel horizontally if the head is activated.

Individual sprinkler heads only operate when heated to their pre-set activation temperature by the hot gases from a fire.  Fire sprinkler heads outside the immediate area of the fire do not open, so water isn’t sprayed onto areas that are not alight, thus reducing the amount of water used and water-related damage, whilst maximising available water pressure.

In pendant design fire sprinkler heads such as that shown in Figure 2, the activation process and make-up of the sprinkler head is fundamentally different to that described for residential concealed fire sprinkler heads.  Every sprinkler head in the system is kept closed by a glass, heat-sensitive, liquid-filled bulb, which serves as a plug, holding back water from the supply pipes. When the temperature around the sprinkler head reaches its pre-set activation level, the bulb breaks as the liquid inside heats up and expands.  The bulb can no longer function as a ‘plug’, thus allowing water to enter the sprinkler head and douse the fire.

Design of Pendant Sprinkler Heads:

Concealed Residential Fire Sprinkler Heads

Unlike pendant fire sprinkler heads, concealed residential fire sprinkler heads are designed to be aesthetically pleasing, not just effective.  The sprinkler head, which is about the size of a down-light, resides in the ceiling void, concealed from view by a flat cover plate which sits flush to the ceiling.   These cover plates are usually white.

Traditional Pendant Fire Sprinkler Heads

Pendant fire sprinkler heads are a traditional design, often used in commercial premises.  Whilst effective, these sprinkler heads sit below the level of the ceiling and contribute little to the aesthetic value of their surroundings.

Placement and Visibility:

Concealed Residential Fire Sprinkler Heads

Concealed residential fire sprinkler heads reside out of sight, and unlike pendant fire sprinkler heads, cannot be seen when not in use.

Traditional Pendant Fire Sprinkler Heads

Projecting below the level of the ceiling, traditional pendant fire sprinkler heads are not concealed and project below the level of the ceiling, remaining in full view at all times.

Summary of Differences:

Concealed Residential Fire Sprinkler Heads Traditional Pendant Fire Sprinkler Heads
Location Ceiling void Project from ceiling
Not visible when inactive Yes No
Blend with surroundings Yes No
Fast Response Activation Yes Yes
Limit water damage Yes Yes
Two stage activation Yes No
Helpful to architects & designers Yes No
Obvious to occupants No Yes
Ease of service Yes Yes

 

Choosing  A Residential Pendant Fire Sprinkler Head

Rarely valued for their aesthetic value, traditional pendant fire sprinkler systems have now been generally replaced by concealed residential fire sprinklers, which not only blend with but enhance the space they’re designed and installed to protect.

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