Douglas Krantz - Technical Writer - Describing How It Works
Get the book Make It Work - Conventional Fire Alarms

Aren't Those Coat Hanger Racks on the Wall?

A Sprinkler Head may look like a good place to hang clothes, but the damage it can do should keep anyone from even touching it.
Even though it looks innocent, this sprinkler head is meant to fight fires. When that red glass vile filled with temperature sensitive fluid breaks, the plug comes off. After that, nothing stops the water.


By Douglas Krantz

Hotels, motels, apartment buildings, condominiums, townhouses, and some newer private homes, all have automatic fire-fighting sprinkler systems. Without anyone needing to do anything, heat from a fire will turn on the water and water sprays out from the sprinkler head.

Because these are places people dwell in and the rooms are people sized rather than business sized, the sprinkler heads are on the walls.

Wall Fixtures

To many people, the sprinkler heads are just chrome plated metal devices on the wall. They look harmless, too small to actually do anything. Besides, the wall fixtures (sprinkler heads) have never done anything before, they're just there.

Sprinkler Heads are Dangerous

But these things scare me. It's not that they can hurt me; the best they could do is get me wet. What scares me is the damage that they are capable of wreaking to the house or apartment building.

Sprinkler Heads are Trigger Happy

To start with, they trigger easily. The only trigger for a sprinkler head is supposed to be heat from a fire. In essence, the heat breaks a fragile temperature sensitive element inside the frame of the sprinkler head.

All that needs to happen, though, is for the temperature in the room to raise enough above a critical point. Once the temperature is high enough, that fragile heat sensitive element breaks. Suddenly the sprinkler head is spraying water.

When there isn't a fire, though, what triggers a sprinkler head more often is the red glass heat sensitive element inside it is bumped and then broken. The fragile trigger element can be broken with a coat hanger, a holiday decoration, or anything else hooked or placed on the sprinkler head mechanism.

Sequence of Events

Whether it's triggered by the heat of a fire breaking the red glass element, or it's triggered by bumping and breaking the fragile sensing element, once that sprinkler head is triggered, a number of events happen.

Water Comes Out

Oh, this isn't nice water like the water coming out of the kitchen faucet. This water has been sitting in the pipe for years and it really stinks. Not only does the water stink, but it comes out black and stains anything it comes into contact with.

Lots and Lots of Water Comes Out

The amount of water coming out of a sprinkler head isn't like the amount of water that comes out of a garden hose or a shower head. The sprinkler head is designed to fight fires and save lives. In just a short time, a sprinkler head sprays out a huge amount of water.

For example, if a sprinkler head sprays water in a 10th floor apartment, water damage will be in the 9th floor apartment below, and in apartments below that, possibly all the way to the 3rd floor. (I've seen the damage.)

The Fire Alarm System in the Whole Building Sounds Off

Once a sprinkler head starts spraying water, the building's fire alarm system considers that a fire is raging. To get everyone out of the burning building, the fire alarm system is now sounding off.

The Fire Department Shows Up

Thinking there's a real fire, the fire department arrives with sirens blaring. If someone accidently activated the sprinkler head, all the fire department does is shut off the water. However by the time the fire department figures out about the broken sprinkler head, the water has already done a lot of damage.

Don't Touch the Sprinkler Head

All this is to say, don't hang a decoration from the sprinkler head, don't hang a hat from the sprinkler head, don't hang a planter from the sprinkler head, and especially don't use the sprinkler head sticking out of the wall as a convenient coat hanger rack.

When there isn't a fire, it's far better not to touch the sprinkler head at all. The risk of water coming out of the sprinkler head is just too great.
Based on his electronics training, and his understanding of Life Safety, Douglas Krantz has compiled his knowledge of Conventional Fire Alarm Systems into the book Make It Work - Conventional Fire Alarms. The book covers the basics of the Conventional Fire Alarm System, and shows how Life Safety and internal supervision affects the fire alarm system.

Douglas Krantz -- Fire Alarm Engineering Technician, Electronic Designer, Electronic Technician, Writer

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