What is the Difference Between Pendant Sprinkler Heads and Concealed Sprinkler Heads?

Understanding how fire sprinkler heads work and the differences between them helps people make informed decisions about the type of sprinklers they want in their commercial and residential buildings. We all expect fire sprinklers to be there if there is a fire, but what happens when they activate under a false alarm? It happens. Most people must wait for the fire department to arrive, assess the situation, and then turn off the sprinkler system. That’s a lot of water and a lot of water damage. Some sprinklers you can turn off yourself with a simple tool called a Sprinkler Stopper. Doing so limits the amount of water damage that occurs. All of these little facts begin to illustrate why the differences in sprinkler heads are so significant. Keep reading as we go through the differences between pendant styled sprinklers and concealed sprinkler heads.

The Pendant Style Sprinkler Head

Pendent sprinkler heads sit out in the open. You’ve probably seen them all over the place when you shop at big box stores. Like a pendant on a necklace, pendent sprinklers face down from the bottom of the pipe.

They consist of:

  • The orifice, which is the opening that connects to the water pipe,
  • The plug
  • A sealed liquid-filled glass tube
  • The frame
  • The deflector.

The orifice is what connects the sprinkler head to the pipe. The plug holds back the water until the liquid-filled glass tube breaks, and then the water flows out and down, where the deflector spreads the water around the space. The frame holds all of these pieces together.

The glass-filled tube breaks as the heat rises (about 136 degrees Fahrenheit,) the liquid expands, and the glass shatters. That action drops the plug, which frees the water. There are two levels of glass tubes for pendent sprinkler heads – a 3mm and a 5mm. The 5mm is standard equipment, while the 3mm is for rapid response environments. Generally, the 5mm glass tube activates when the temperature reaches 136 degrees Fahrenheit. Not all sprinklers go off at once, though that is a common misconception.

When to Use the Sprinkler Stopper

In case of a false alarm, or when the sprinklers activate, and there is no fire, use the Sprinkler Stopper. Most sprinklers discharge about 60-gallons of water per minute. It is the best tool to stop water and water damage quickly.

Parts of a Concealed Sprinkler Head

Concealed Sprinklers and pendent sprinklers are similar. They differ because the concealed sprinkler sits in special holes in the ceiling and has a few extra parts. The cup holds the sprinkler to the pipe, while a cover conceals the unit. A cover on the bottom of the sprinkler hides it from view. Inside is the glass-filled tube that, when removed, activates the water.

As the heat from a fire rises, the cover over the concealed sprinkler is the first thing that drops. Then the heat has direct access to the liquid-filled glass tube. On some models, the pendant portion of the concealed sprinkler falls when the cover does. On other models, it remains compressed until the glass tube breaks. When the glass tube breaks, the water is released. Accidental activation is the most common cause of releasing water from a sprinkler system.

Like on the Pendent sprinkler head, you can use the Sprinkler Stopper tool to stop water flow if there is a false activation.

Which type of Sprinkler Head is Right for Your Building?

It comes down to aesthetics. You find concealed sprinkler heads in high-profile buildings, homes, and office buildings where an exposed sprinkler might not fit the decor. You find Pendent sprinklers installed in commercial settings, warehouses, and distribution bays.

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