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

There's a Dry Sprinkler System Here, How Does It Work?

As long as there is pressurized air in the dry system, the dry system valve, in blue, keeps the water out of the dry system.
The Dry Sprinkler System Valve is in blue on the right


By Douglas Krantz

When a fire starts burning in a building, action needs to be taken early... before the fire has grown out of control.

Taking this action, sometimes before anyone even knows about the fire, is the Automatic Sprinkler System. Heat from the fire activates a sprinkler head, and water, now spraying from the activated head, suppresses the growth of the fire.

What is a Dry Sprinkler System?

A wet sprinkler system has water in the pipes. A dry sprinkler system, even though it will spray water on a fire, has no water in the pipes; only pressurized air.

Why Install a Dry System?

In northern climates during the winter, inside attics and garages, water in the pipes of a wet sprinkler system will freeze and break the pipes. Lots of mess.

The water can't be in the pipes where it can freeze, but water is needed in a fire sprinkler system for spraying on a fire. This is a dilemma.

To solve the dilemma, instead of the water in the pipes of a wet sprinkler system, the dry sprinkler system keeps pressurized air inside the pipes, and the air doesn't freeze.

Division

To keep the water out, like a dam on a river, a clapper valve is used to divide the wet pipes from the dry pipes. Holding back the water, pressurized air inside the dry sprinkler system pushes against the clapper, keeping the clapper closed.

Heat Lets the Air Out

When the heat from a fire melts a link on a sprinkler head, the sprinkler head opens and lets the air out.

Water Fills the Pipes

By itself, of course, this doesn't do anything, but once the air is let out, there's nothing to hold the clapper closed, and water rushes into the dry system like a dam bursting. The dry sprinkler system has become a wet system.

At this point, like a firefighter with a hose, the water sprays out and quenches the fire.

When heat melts the link in a sprinkler head, because as far as the dry sprinkler system is concerned it's suppressing a real fire, the building fire alarm system is going to sound off and call the fire department.

Dry Sprinkler Fire Suppression System

Being ready to spray water on a fire, a dry sprinkler system will suppress a fire, even though, until heat from a fire activates one of the sprinkler heads, the pipes are filled with pressurized air.
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

Share This With Friends:

 Get your free diagram showing supervision for Class B wiring

Go to the Fire Alarm Description Map Page of Douglas Krantzs Technicians Corner
Go to the Residential Life Safety Map Page of Douglas Krantzs Technicians Corner
Go to the Residential Life Safety Map Page of Douglas Krantzs Technicians Corner
Go to the Fire Alarm Description Map Page of Douglas Krantzs Technicians Corner
Go to the General Electrical Map Page of Douglas Krantzs Technicians Corner
Go to the Fire Alarm Maintaining Map Page of Douglas Krantzs Technicians Corner
Go to the Fire Suppression Map Page of Douglas Krantzs Technicians Corner
Go to the Guest Writer's Guidelines of Douglas Krantzs Technicians Corner
See Trivia on Douglas Krantzs Technicians Corner
This website uses cookies. See Privacy for details.
Get the book Make It Work - Conventional Fire AlarmsGet the book Make It Work - Conventional Fire AlarmsGet the book Make It Work - Conventional Fire AlarmsGet the book Make It Work - Conventional Fire AlarmsGet the book Make It Work - Conventional Fire Alarms
Get the book Make It Work - Hunting Ground Faults
Get the book Make It Work - Hunting Ground FaultsGet the book Make It Work - Hunting Ground FaultsGet the book Make It Work - Hunting Ground FaultsGet the book Make It Work - Hunting Ground FaultsGet the book Make It Work - Hunting Ground Faults
Reader's Favorite Articles

What is a Stair Pressurization Fan (SPF)?

Which Way Does Electricity Flow?

What's the Difference Between Class A and Class B?

What Makes the End of Line Resistor So Important?

What is a Flyback Diode?

What is a Fire Alarm System?

What is an RTU (Roof Top Unit)?

What Causes an Open NAC?

Recent Articles

Should the Generator Stop when the Horns Stop?

Why Can't I Reset the Panel After Disconnecting the SLC?

I'm Getting Desperate Dealing with False Alarms...

Help! I Have Some Weird NAC Troubles

Can the Fire Alarm System be Fixed so It Can Be Heard?

How Can a Door Holder be Hot and Buzzing?

Why Won't the Added Horns and Strobes Work?

What is the Difference Between a Fire / Smoke Damper and a Fire Damper

How do Pathways Affect Ground Faults?

Why Won't the Panel Show the Detectors?

When Testing, Why Isn't the LED Lit Continuously?

Why Don't All of the Smoke Detectors Act the Same?

Is There a Procedure to Install EST Detectors?

Does it harm the panel if the trouble occurs during a weekend and lasts 2 or 3 days?

The fire alarm bell to my house is going off...

How is an Addressable Elevator Capture Panel Connected to a Conventional Panel?

Why Does Closing Some Gatevalves Show Trouble?

Home Wateflow Switch - Do you know how to reset it?

How is a Pathway Classified?

Just Who Is the Authority Having Jurisdiction (AHJ)?

What are Pull-Up or Pull-Down Resistors?

Do we need horns and strobes in a building shell?

Don't Breathe Smoke

The Pump was Very Hot - What Happened?

Learn about fire alarms, one article at a time -

Keep up on the latest article!




No Charge - Unsubscribe Anytime