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#53 - The Role and Components of Fire Department Connections

Posted by Jason Hugo & Cameron Sharp on 7/8/2016
Fire sprinkler systems are an invaluable resource in fire protection. These systems, however, are of little value without the fire department connection (FDC).  In the event of an emergency, the FDC is the access point for a building’s sprinkler system to receive supplemental water from fire engines, which initially draws from fire hydrants on-site. During larger fires, a building can deplete almost all of its water supply. FDCs become quite essential in such a scenario, and are one of the only ways for firefighters to have an immediate impact on increasing this supply of water. National Fire Protection Association (NFPA) 13, Standard for the Installation of Sprinkler Systems, requires FDCs for nearly all sprinkler systems. 

Not interested in a detailed explanation of FDC use cases and options? Rather see all our FDC options? Jump directly to our Fire Department Connection product category.

An FDC is comprised of three components: the body, swivel, and inlets. The body serves as the connection between the FDC and the standpipe or sprinkler system. Most FDCs have a four-inch (4”) or six-inch (6”) outlet which connects to the building’s internal piping. The swivel is an attached, threaded brass ring that connects the fire hose to the FDC during an emergency, and breakable caps or plugs, the rest of the time, to prevent foreign material from clogging pipes. An FDC’s inlets include one or more clappers, which control the flow of water and regulate servicing hoses. 

Today several variations of the FDC exist: exposed, freestanding, and flush. 

Exposed FDCs (single/double clapper two-way inlets & triple clapper three-way inlets) are found on the outside wall of a building and require breakable caps or plugs for protection. This design economically satisfies fire department inlet requirements. 

*Dual female-inlet FDC

Freestanding connections serve the same purpose as that of exposed FDCs, they just remain separate from the building being supplied; connecting to the building’s sprinkler system through a buried pipe. Buildings use freestanding FDCs when the proximity between a hydrant and a FDC could create obstruction violations from fire apparatus.

*Freestanding FDC
Flush connections are, as the name implies, flush to the building’s wall. They are considered more aesthetically appealing, especially when the building requires three or more inlets.

*Flush, two-inlet fire department connection
Location, Location, Location!

The location of an FDC is of paramount importance. It depends on the codes or standards of your jurisdiction, but it is recommended to be positioned on the street side of the building and recognizable. The engine and its hoses should not obstruct access to the building once connected to the FDC. Otherwise, access for the ladder company becomes restricted and positioning an aerial master stream for larger fires is more difficult. In addition to the items above, you may also want to consider how your FDC is positioned on the building relative to the nearest hydrant – anything less than 100 feet is optimal. It can be just as troublesome to have the FDC located right next to a hydrant as well. In such a scenario, a pump apparatus, which has to locate itself by the hydrant, would also be in front of the FDC. Code prohibits this for safety reasons and obstruction in firefighting operations. 


FDCs are required to be marked with minimum signage, such as: “Automatic Sprinklers”, “Standpipes”, “Standpipe & Auto-Sprinkler” or “Test Connection”. Most fire equipment manufacturers provide escutcheon rings to label these connections effectively. The intended purpose of signage is to provide first responders with specific system information for effective support. This could be information about what type of sprinkler system is involved, as well as whether or not an FDC-connected system reaches throughout an entire building. If you need a replacement FDC escutcheon, the most common size is a 4” inner diameter, like the “Auto Spkr” escutcheon available here.

Threads and Hose Connection Sizing

The hose connections on an FDC should always be agreeable with local fire apparatus. All too often FDCs are installed, only to find that it contains threads that are sized differently from what is used locally. NFPA 13 requires female swivel fittings on FDCs. It is important to keep this in mind because some exterior connections, such as a roof manifolds or fire pump test connections, can resemble an FDC, but are actually not.

*Male-threaded Roof manifold

For example, buildings with fire pumps have what’s known as a fire pump test connection, or test header as it’s called in the industry, which is located outside, and enables flow tests to verify fire pump operation potential. It looks similar to an FDC except that it has male-threaded hose connections. Any crew that attempts to connect the male end of a fire hose would be stymied. 

Traditionally, the industry has considered the standard FDC to have two 2 ½ inch female swivel connections, known as the Siamese connection. Fire department connections, however, can range from one to eight female connections. 

As previously mentioned, FDCs contain clappers within their inlets. A two-way FDC comes with either single or double clappers. What’s the difference? Double clappers are more expensive and often sought for larger systems. They are the most durable for handling several flows of water, and their design provides a safeguard against bursting hose lines. Single clappers are cheaper because they use less material, which reduces manufacturing costs. 

A clapper’s ability to channel and direct water does several things. First, it prevents water from flowing back out of the FDC; this allows you to connect and disconnect more than one hose to an FDC without leakage. Second, if one of those servicing hoses were to burst, the flow of water never becomes interrupted because the clapper would automatically cover the unused inlet via water pressure. Regardless of the number of clappers, the count of which rises in line with the number of inlets, they all open and allow incoming water to flow through standpipe systems. They swing freely and keep closed any remaining unused inlets, to prevent backflow from occurring.

*Both clappers can be seen closed 

Standpipe versus Sprinkler Systems

FDCs are a key component for charging standpipe systems. These systems are designed to provide water to servicing hoses in strategically placed locations inside a building or structure. They are most common in large buildings, where areas of the facility are too far from an outside entrance, and multistory buildings to prevent long lengths of hose in stairwells and on the ground. Dry standpipe systems require external charging from outside sources of water. An FDC connection, located at the ground level, is the liaison that connects the building’s system to the fire engine, which connects to a nearby fire hydrant. The water then reaches a standpipe riser that distributes it throughout and to the top floors of a building. 

Sprinkler systems are equally dependent on FDCs. Even though they may already contain water (unless a dry sprinkler system), supplemental water can be crucial during certain emergencies. This is where signage becomes quite important. A first responder arriving on scene needs to know, quickly, which connection is the right one. FDCs for both sprinkler systems and standpipe systems look similar, and at times can be located within feet of one another. 

Browsing for an FDC?

Before replacng an FDC, you want to check several things, including the number of female inlets and clappers, thread type, as well as whether or not to order breakable caps or FDC plugs. If you’re replacing an FDC, the easiest way to do this is to purchase the same model. If purchasing a new FDC, follow NFPA 14, Standard for the Installation of Standpipe and Hose System, along with your current system specifications to determine the correct model. For example, some standpipes require 90 degree FDCs in place of the traditional – you’re going to want to know this difference! 

Once you have chosen the correct model, it is time to decide the finish – cast brass or polished chrome? Both options are equally durable and can withstand weathering for extended periods of time. What about breakable caps or plugs? Your new FDC needs to be protected; FDC plugs commonly come standard for their added durability and prevent foreign material from clogging hose connections. However, for firefighter convenience breakable caps can be purchased. These caps, instead of fastening into the FDC swivel like plugs, latch onto the lugs using eyehooks. For more information on the differences between breakable caps and plugs read FDC Caps or Plugs: What are my Options?

QRFS.com is proud to offer FDCs of all kinds. A thorough search through our inventory is recommended, it can be easy to get lost in all our options! Keep in mind that some models come standard with FDC plugs. For the FDCs that don’t, simply jump over to our plugs and caps section. To fulfill minimum signage requirements, determine if the purchased FDC comes with a titled escutcheon, if it doesn’t check our inventory of signs. Visit us today, and be on your way to a complete fire protection program.

This blog originally posted by Jason Hugo and Cameron Sharp at QRFS.com/blog on July 8, 2016. If you like what you've read, check us out at Facebook.com/QuickResponseFireSupply or at Twitter @QuickRsponseFS.

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