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FDC Hook Up: Do The Twist

The couplings on the FDC can seize up and not be free enough to spin


(Fire Engineering photo)


By Mark van der Feyst | Fire Engineering

Not every fire department will encounter fire department connections (FDC) in their response area. For those departments that are covering suburban and urban areas, you will encounter them. FDCs are not just reserved for high-rise buildings. They will be found on single-story large structures, low-rise buildings, and parking garages.

FDCs will be located on the outside of the building at a spot to be accessible by the fire department; this may be by the front entrance of the building. Some buildings will have the FDC located away from the building and standing alone like a pressure-reducing valve by the street. Regardless of the location, they are designed to allow the fire department to provide water on the inside for interior operations.

There are two types of FDCs: threaded and storz. The storz type will be a single inlet of either 4, 5, or 6 inches, depending on the structure itself and the department’s specifications for their local building code. With the storz being a sexless coupling, there is no problem that can occur when connecting except for damaged lugs on the coupling or the coupling not being perfectly round and somewhat oval, making it difficult to connect.

A problem that can occur with the threaded FDC is the seizing of the couplings on the FDC. Female couplings are present on every FDC and allow the male coupling to be threaded into the FDC. With exposure to weather, dirt, and rust, the couplings on the FDC can seize up and not be free enough to spin. When this happens, the male thread cannot be connected.

One way to alleviate this problem is to twist the hose in the opposite direction about five or six times. This twisting of the hose allows the hose to untwist in the right or clockwise direction while at the same time allowing the male coupling to be threaded into the female coupling without spinning the female coupling.

Preplanning will also alleviate this problem by checking to see if the couplings spin freely or not. If they do not, the property owner needs to be notified so that they can fix the problem.    

Equipment needed: Two 2 ½-inch length of hoses, spanner wrench, access to an FDC

Goal: To practice securing the FDC using the twist method with the hose


  1. Locate the FDC on the building. Identify the type of FDC (thread or storz.)
  2. Remove the caps from the FDC.
  3. Look inside the female coupling to spot any debris or obstructions inside.
  4. If any garbage or debris found inside, use the spanner wrench to clean it out.
  5. Take one 2 ½-inch hose and twist it five to six times in the counterclockwise
  6. Starting with the left 2 ½-inch female FDC coupling, make the thread connection with the hose to the FDC and untwist it going clockwise to the right.
  7. Once the hose has been threaded into the coupling, use the spanner wrench to tighten the coupling.
  8. Repeat the same for the other FDC coupling on the right side.
  9. Use a piece of webbing or rope to secure the two hoses together.

Key Points:

  1. Threaded FDC couplings can seize and require the hose to be connected by twisting the hose in the opposite direction.
  2. Start with the left FDC coupling to provide the room to untwist the hose to the right for both FDC connections.



Mark van der FeystMark van der Feyst has been in the fire service since 1999 and is a full-time firefighter in Ontario, Canada. He is an international instructor teaching in Canada, the United States, and India, and at FDIC. Van der Feyst is a local level suppression instructor for the Pennsylvania State Fire Academy. He is also the lead author of Residential Fire Rescue (Fire Engineering Books & Video).

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