What are the main components of a fire sprinkler system?
A fire sprinkler system is constructed from several pieces.
Let's start from the source and work our way as water flows.
Most sprinkler systems are fed by a public water supply.
This is often a water tower (or towers) that feed a gridded pipe network.
Individual buildings tap this pipe network, with a tap at the street and a feed into an individual building.
This feed is usually called the service entry.
A backflow preventer is usually required by plumbing codes on the service entry.
It can be located on the service main outside or just inside the building.
In warm environments, it can be common to have the backflow preventer outside and exposed aboveground.
In colder climates, backflow preventers are often in heated enclosures or inside the building.
The backflow preventer only allows water to flow in one direction.
This prevents contamination from any stagnant water, bacteria, or toxins back to the city main.
After a backflow preventer is the feed to the fire sprinkler riser.
This feed could be as simple as a horizontal pipe feeding vertical pipes with control valves, which we would typically refer to as a riser assembly or riser manifold.
But for tall multi-story buildings, this could a vertical sprinkler riser where control valves are located on each floor level.
In either scenario, the next component the water is going to see is the control valve.
Control valves allow the system to be divided into zones.
These zones are helpful for maintenance, repair, renovations, or shutting off a portion of a system after a fire is extinguished.
After the control valve water would then see an alarm valve, a water flow switch for wet systems, or a dry valve or pre-action valve for dry and pre-action systems.
An alarm valve and water flow switch are used to alert the monitoring system when there is water flowing out to the sprinklers.
Dry and pre-action valves serve as the barrier between pressurized air in the pipe and the water chamber below.
When water flows through these, a signal is also sent to activate sprinkler monitoring or fire alarm system.
As the water flows it would then go to a feed main, which is the pipe between the riser and the cross main.
The cross main, next, is the portion of main pipe that connects, or “crosses,” the branch lines.
Then just like a tree, branch lines (or branch pipe) carry the water all the way out to the fire sprinkler themselves.
That is the main flow path that water experiences from the source to a sprinkler.
Sprinkler systems include other attachments as well.
Each system is required to have a drain, a way to test monitoring devices, a way to tell how much pressure is in the system, and a method for the fire department to supplement additional water and pressure.
These are all achieved by main drains, inspector’s tests, pressure gauges, and fire department connections.
There are also major add-ons and other combinations too, like water storage tanks, fire pumps, and standpipes.
We will break out each of these and more in detail, but for today, that’s about it for the main components that go into a sprinkler system.
I'm Joe Meyer, this is MeyerFire University.
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