A dequate water flow and pressure are critical for successful fire control, especially when automatic sprinkler and standpipe fire suppression systems are in use. But water supply valves on these systems may be closed, an area’s water supply may lose pressure over the years as more and more demands are placed on it, pressure in a city water supply may fluctuate often, or a water supply may be limited if it comes from gravity or pressure tanks.
Thus, to keep sprinkler and standpipe systems reliable, an auxiliary water supply is usually necessary. Fire department connections are a means of providing it.
A fire department connection (FDC) is a dry pipe that has one or more female swivel coupling inlets on one end; at the other end, it’s connected to the suppression system. Hose lines can be attached to the inlets to introduce water directly into the suppression system from a pressure source, such as a pumping engine.
In most instances, the FDC pipe is tied into the system on the system, or “downstream,” side of all control valves. This, in effect, bypasses all valves in the system that could be shut off.
Of course, the FDC itself must be reliable, and that means proper plan reviews, inspections, and firefighting procedures.
Suppression system plans submitted for approval give the fire department an opportunity to verify compliance with applicable fire protection codes and standards. The guidelines in this article are taken from a number of such documents.
Placement. The FDC can be found in one of two places: on the protected building or “in the yard” (somewhere on the grounds surrounding the protected building).
It should be placed to the best advantage: close to a water source. Long hose stretches should be avoided. Also consider how a fire within the protected building would hamper use of the connection. Avoid placing the FDC near openings in the protected structure or near the building’s gas and electric services. Take into account the possibility that exposure fires in nearby buildings could create intense radiant heat around a potential FDC site.
Locating the connection on the front, or “street,” side of the building provides the best location and is usually required by codes or standards. However, if there are large building setbacks or if other structures and obstructions would block the FDC on the street side, the connection might be better placed on some other side.
The FDC should be situated so as to avoid mechanical damage as well as blockage by motor vehicles, fences, signs, or landscaping. Avoid placing the FDC in or around loading docks. Bollards— vertical, cement-filled pipes—and designated fire zones are useful for keeping an unobstructed, clear path to the FDC.
The FDC must be given adequate clearance to allow the connection of hose lines for supply without kinking them; in most codes, that’s a minimum of 18 inches from the ground to the center line of the connection, and a maximum of 42 inches.
FDCs located in the yard and connected to a private, underground water supply network must be reviewed carefully. Fire department connections are sometimes used to supply yard hydrants, standpipe system outlets in open areas that appear as hydrants. These aren’t the hydrants typically found throughout municipalities. True yard hydrants are” being installed very few and far between today. Yard hydrants are designed to be attached directly to handlines rather than supply pumpers. (They seldom have a steamer connection to service pumpers.)
Piping arrangement. Although both sprinkler and standpipe systems contain open stem and yoke valves, post indicator valves, and wall post valves, only the standards for sprinkler systems address where the FDC piping should be located in relation to these water supply control valves.
Photo by Glenn P. Corbett
Promptly stretching supply lines to the fire department connection of the exposure building on the left helped save the structure. But how fast would responders be able to find and use an FDC that’s…
When located on a building and servicing a single wet-pipe sprinkler system riser, the FDC pipe is tied in on the downstream side, beyond the location of the riser control valve and either an alarm check valve or a water flow alarm switch. (See Figures 1 and 2 on page 44.) On a dry-pipe sprinkler system riser, there’s a dry alarm valve instead of an alarm check valve or water flow alarm switch, and the FDC is tied into the system between this and the riser control valve. (See Figure 3 on page 47.)
Buildings with multiple sprinkler risers may connect the FDC pipe on the supply side of all risers, but beyond the main control valves. In this way, with a single system riser shutoff, the FDC can still supply all other system risers. (See Figure 4 on page 47.)
Check valves, which allow water flow in only one direction, are also important in the FDC piping. A check valve is necessary between the hose connections and the suppression system piping to keep water from flowing back out of the hose connections. This check valve should be placed as close as possible to the point of connection between the FDC piping and the suppression system piping.
Another check valve is needed in the suppression system’s water supply piping. It’s located “upstream”—toward the supply side—of the FDC piping tie-in, so when an engine company uses the connection, water won’t be pumped back into the main water supply (the city water mains, storage tanks, or whatever).
Fire department connections should never be tied into the supply side of the system’s fire pump. That would place two pumps in a series, which could put excessive pressure on the suppression system piping, possibly causing it to burst.
Verify on the plans that the water main supplying the nearby municipal hydrants doesn’t also supply the protection system. Pressure and volume being supplied by a pumping engine to the FDC could be “stolen” by the hydrant main in a loop. Such a condition would result in water being circulated in the underground municipal water supply rather than into the suppression system.
Sizing. Standpipe standards don’t give any design criteria for the sizing of FDC supply piping or the number of inlets to be provided. But sprinkler standards do, and these can be a guide for standpipe use, as well.
FDC supply piping must be large enough to supply sprinkler system water demands as calculated in a hydraulic design or as stipulated in a pipe schedule, a chart that indicates the maximum number of sprinkler heads that can be fed from a specific pipe size. Can your engine company supply these system demands with the size of pipe specified in the design? In some cases, it may be necessary to make the FDC supply piping larger.
According to National Fire Protection Association Standard 13, “Standard for the Installation of Sprinkler Systems,” the FDC supply piping to the sprinkler system must be a minimum of four inches in diameter, except that sprinkler risers three inches or smaller may use three-inch FDC supply piping. Sprinkler system risers with fireboat connections must be a minimum of six inches in diameter.
Hose connection inlets. For sprinkler risers three inches or less in diameter, a single hose connection is usually permitted. NFPA 13 says that a minimum of two inlets are to be provided for larger sprinkler risers. A good rule of thumb is to provide a minimum of one 2Viinch inlet for each 250 gpm of system water demand. Of course, the inlet coupling threads should match the fire department’s hose threads, and the coupling itself should be provided with a plug.
camouflaged by paint?
Photos by Glenn P. Corbett
in a loading dock?
flush with t_____round
Clappers must be provided for each inlet so additional hose lines may be attached after the first one has been charged. The clapper swings only in the direction in which the water supply is flowing and will prevent water from flowing back out of the connection. (A two-way Siamese, however, may have a single clapper. In that case, the firefighter attaching a hose must be sure to make the first connection with the inlet that doesn’t have the clapper, to take advantage of the protection against backflow that the clapper in the other inlet provides.)
Other pertinent factors. As with all other suppression system components, all portions of the FDC must be rated for fire protection use. Manufacturers’ specification sheets should be submitted for approval with the system plans and calculations.
Automatic drip valves must be provided so that, after it’s used, the FDC piping can be drained of water.
The FDC piping must be supported throughout, with hangers and pipe stands for interior piping and thrust blocks (supports made of concrete or stone slabs) for underground piping.
Signs must be provided to indicate what the connection supplies—sprinklers, standpipes, or a combination of both. If the FDC supplies only a portion of the building, that too must be noted on the sign. For example, on structures that face more than one street or have multiple-zone sprinkler protection, there may be several fire department connections, and the areas served by each zone must be identified.
Once the plans have been approved, the system must be properly inspected and tested in the field prior to final acceptance by the fire department. Make sure the FDC has been installed according to the plans and specifications found on the device. Check that the individual inlet couplings move freely. Bring a double male fitting to verify that the couplings have the correct threads. Clappers inside the connection should be present and should move easily. Plugs must be provided to protect the swivels and keep out debris.
The FDC should be readily discernible from surrounding objects. Some fire departments require that it have a distinctive color, while others require a visual signal (such as a light) to pinpoint the connection’s location for firefighters.
The FDC and piping must be flushed of all construction materials and other debris, and then a hydrostatic test must be performed, at 200 psi for two hours or at 50 psi above the maximum working pressure of the system if that pressure exceeds 150 psi.
To ensure that FDCs will be working and accessible when needed, they should be part of a fire department’s regular inspections of all of a community’s suppression systems.
Over time, various obstructions often appear near the FDC. Landscaping is added, fences are erected, and garbage dumpsters are placed near the connection. Building owners must be instructed to keep the area around the FDC clear so fire apparatus can reach it readily.
When buildings are painted, the FDC also usually receives a coat of paint. This can make the FDC less visible and, worse, it can stop the swivel inlet coupling from moving freely.
Rust can also inhibit the swivel action.
Probably the most common problem is missing plugs. An FDC without these protective coverings is an open invitation to litter and other debris. If water were to be pumped into the suppression system, the debris would create substantial problems during firefighting operations. If the plugs are missing and there’s any doubt that the pipe is clear, the pipe should be flushed.
As in the acceptance inspection, the double male fitting should be used during periodic inspections. The swivel coupling should be checked to make sure it hasn’t been cross-threaded. It should also be verified that the coupling hasn’t become “out of round,” usually as the result of a motor vehicle striking it.
All firefighters must know the location of all fire department connections in their response area and should include that information in their prefire plans. They should also know the location of the water supply they’ll use, as well as how reliable the water supply is.
behind a fence?
blocked by trash?
When there’s a fire in a building protected by a suppression system with an FDC, one of the first-arriving engine companies should lay supply lines to the connection. All connections on the building should be used; having several hose lines attached ensures a water supply even if one of them bursts, and the connections become more important as a growing fire increases the system demand.
The firefighter attaching a hose to the FDC should have, in addition to the hose lines, a hand lamp, a spanner wrench, and a few sets of fittings. A hand lamp is not only necessary for night operations, but is also useful to check inside the FDC for debris. Spanners are necessary to tighten the hose to the FDC, especially since gaskets are seldom, if ever, present in the female swivel coupling. Fittings are useful when the swivel coupling is “frozen”—a double male fitting is screwed into the inlet coupling first, and then a double female and a hose line are attached.
Most pertinent literature recommends that the FDC on a sprinkler system be pressurized at between 125 and 150 psi. Recommendations for standpipes up to 100 feet in elevation are 100 psi for solid-stream nozzles and 150 psi for spray nozzles. For standpipes more than 100 feet high, 5 psi should be added for each additional floor.
It must be emphasized that many suppression systems are designed for working pressures of up to 175 psi. Others, especially those in high-rise buildings, may use higher working pressures.
These are all generalized recommendations. The actual parameters of an individual system must be determined before there’s a fire, through hydraulic calculations performed for the system design. Actual fireground conditions will also be a strong, determining factor in choosing pressures. The draw-down by handlines and master streams must be taken into account because it will reduce the amount of water available to the suppression system unless the supply pressure is increased.
Hose lines should remain attached to the FDC until after final extinguishment and overhaul. In case of a rekindle, the hose lines can be charged quickly.
Once the hose lines are removed, proper drainage of the FDC piping should be verified by checking inside the connection with the help of a hand lamp. Finally, the plugs should be replaced.
These specifications, which are contained in a variety of codes and standards, should provide guidance in the review, inspection, and use of the fire department connection. But firefighters also need to know the provisions of their own, local fire prevention codes.