How is Number of FDCs Determined in NFPA 15?

6/20/2024

We have a project using a deluge water spray system under NFPA 15.

We have installed 4 Fire department connections with 5" Storz inlet.

Our client is asking us if the number of FDCs installed is sufficient as mentioned in NFPA 15 Section 6.4.3.3.

My question is - how do we know that the number of outlets and size of the fire department connection is sufficient?

How is that determined?

Thanks in advance.

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9 Comments

Pete H

6/20/2024 06:55:03 am

Take it with a grain of salt, I don't work with NFPA 15 that much but my take is:

The following questions would need to be answered:

What size is your riser the FDCs are attaching to?
Is there a standpipe system?
Is the building fully sprinklered?

They say "in accordance with NFPA 13" in NFPA 15 6.4.3.4 (2022 ed.).

NFPA 13 (2016 ed.) 6.7:

6.7.1 Unless the requirements of 6.7.1.1, 6.7.1.2, or 6.7.1.3 are met, the fire department connection(s) shall consist of two 2-1/2" connections using NH internal threaded swivel fitting(s) with "2.5-7.5 NH standard thread," as specified in NFPA 1963.
6.7.1.1 Where local fire department connections do not conform to NFPA 1963, the authority having jurisdiction shall be permitted to designate the connection to be used.
6.7.1.2 The use of threadless couplings shall be permitted where required by the authority having jurisdiction and where listed for such use.
6.7.1.3 A single outlet fire department connection shall be acceptable where piped to a 3" or smaller riser.
6.7.2 Fire department connections shall be equipped with approved plugs or caps, properly secured and aarranged for easy removal by fire departments.
6.7.3 Fire department connections shall be of an approved type.

----

This changes if you have standpipe, where now you need a 2-1/2" inlet for every 250 gpm of system demand to a maximum system demand. If the building is fully sprinklered, the maximum system demand is 1000 gpm so four 2-1/2" inlets. If it is not fully sprinklered, it goes to 1250 gpm or 5 2-1/2" inlets.

Glenn Berger

6/20/2024 08:09:56 am

The answer to your question is dependent on the water requirements (demand) to the suppression system.

One 2-1/2 inch connection is typically used for each 250 gpm of flow required.

Dan Wilder

6/20/2024 08:43:54 am

Discuss with the local responding FD as to their SOP/SOG and allowances. I'm not sure if the question states there are 4 separate FDC locations each with a 5" Storz connection (assuming that any single location is sized for the water demand of the system) or if there is a single FDC location with a 4-way 5" Storz connection (less likely but still an option). Ultimately, provide enough connections to meet the flow demand of the system using the allowed GPM allowance based on connection size and the signage for the responding FD to know what they need to provide. Most FD's don't have the ability to discharge more than 2 Storz connections.

Typically, each 2½" connection is 250 GPM, Storz can range from 500GPM (4" Storz) to 1000 GPM (5" Storz) and there are AHJ's that request a combination of both for FDC connections..

Some good conversation on this thread
https://www.meyerfire.com/daily/capacities-of-fire-department-connections

and this article
https://nfsa.org/2020/05/01/technical-justification-for-large-diameter-fire-department-connections/

Todd E Wyatt

6/20/2024 09:07:33 am

Per the scoping Code (e.g. IBC-2021), NFPA 15 is not a referenced standard per Chapter 35.

FDCs are referenced in “Section 912 Fire Department Connections” which states “FIRE DEPARTMENT CONNECTIONS shall be installed in accordance with the NFPA standard applicable to the SYSTEM DESIGN and shall comply with Sections 912.2 through 912.6.” (See REFERENCES below).

As others have stated, the FDC quantities & capacities are based on the building’s Fire Protection Systems (e.g. automatic sprinkler systems, standpipes, fire pump, etc).

“NFPA 15-2017 Standard for Water Spray Fixed Systems for Fire Protection” is referenced by the IFC-2021 in 1207.5.5 & 5704.2.9.2.3 but both references do not include FDC references.

NFPA 15-2017 includes FDC requirements including the following, “Fire department connections are not intended to deliver a specific amount of water” and “… number of outlets and size of the outlets and piping in the FIRE DEPARTMENT CONNECTIONS shall be sufficient to supply the water spray system demand.”

FDCs are referenced (14) times in NFPA 15-2017.

Todd E Wyatt

6/20/2024 09:08:07 am

REFERENCES

IBC-2021
Chapter 9 Fire Protection and Life Safety Systems
Section 912 Fire Department Connections
912.1 Installation
FIRE DEPARTMENT CONNECTIONS shall be installed in accordance with the NFPA standard applicable to the system design and shall comply with Sections 912.2 through 912.6.
912.2 Location
With respect to hydrants, driveways, buildings and landscaping, FIRE DEPARTMENT CONNECTIONS shall be so located that fire apparatus and hose connected to supply the system will not obstruct access to the buildings for other fire apparatus. The location of fire department connections shall be approved by the fire code official.
912.2.1 Visible Location
FIRE DEPARTMENT CONNECTIONS shall be located on the street side of buildings or facing approved fire apparatus access roads, fully visible and recognizable from the street, fire apparatus access road or nearest point of fire department vehicle access or as otherwise approved by the fire code official.
912.2.2 Existing Buildings
On existing buildings, wherever the FIRE DEPARTMENT CONNECTIONS is not visible to approaching fire apparatus, the FIRE DEPARTMENT CONNECTIONS shall be indicated by an approved sign mounted on the street front or on the side of the building. Such sign shall have the letters "FDC" not less than 6 inches (152 mm) high and words in letters not less than 2 inches (51 mm) high or an arrow to indicate the location. Such signs shall be subject to the approval of the fire code official.
912.3 Fire Hose Threads
Fire hose threads used in connection with standpipe systems shall be approved and shall be compatible with fire department hose threads.
912.4 Access
Immediate access to FIRE DEPARTMENT CONNECTIONS shall be maintained at all times and without obstruction by fences, bushes, trees, walls or any other fixed or moveable object. Access to FIRE DEPARTMENT CONNECTIONS shall be approved by the fire code official.
Exception: Fences, where provided with an access gate equipped with a sign complying with the legend requirements of this section and a means of emergency operation. The gate and the means of emergency operation shall be approved by the fire code official and maintained operational at all times.
912.4.1 Locking FIRE DEPARTMENT CONNECTIONS Caps
The fire code official is authorized to require locking caps on FIRE DEPARTMENT CONNECTIONS for water-based fire protection systems where the responding fire department carries appropriate key wrenches for removal.
912.4.2 Clear Space Around Connections
A working space of not less than 36 inches (762 mm) in width, 36 inches (914 mm) in depth and 78 inches (1981 mm) in height shall be provided and maintained in front of and to the sides of wall-mounted FIRE DEPARTMENT CONNECTIONS and around the circumference of free-standing FIRE DEPARTMENT CONNECTIONS, except as otherwise required or approved by the fire code official.
912.4.3 Physical Protection
Where FIRE DEPARTMENT CONNECTIONS are subject to impact by a motor vehicle, vehicle impact protection shall be provided in accordance with Section 312 of the International Fire Code.
912.5 Signs
A metal sign with raised letters not less than 1 inch (25 mm) in size shall be mounted on all FIRE DEPARTMENT CONNECTIONS serving automatic sprinklers, standpipes or fire pump connections. Such signs shall read: "AUTOMATIC SPRINKLERS," "STANDPIPES," or "TEST CONNECTION," or a combination thereof as applicable. Where the FIRE DEPARTMENT CONNECTIONS does not serve the entire building, a sign shall be provided indicating the portions of the building served.
912.6 Backflow Protection
The potable water supply to automatic sprinkler and standpipe systems shall be protected against backflow as required by the International Plumbing Code.

NFPA 15-2017
5.10 FIRE DEPARTMENT CONNECTIONS.
5.10.1
Unless the requirements of 5.10.1.1, 5.10.1.2, or 5.10.1.3 are met, the FIRE DEPARTMENT CONNECTIONS shall consist of two 2-1⁄2 in. (65 mm) connections using NH internal threaded swivel fitting(s) with “2.5–7.5 NH standard thread,” as specified in NFPA 1963. [13:6.7.1]
5.10.1.1*
Where local FIRE DEPARTMENT CONNECTIONS do not conform to NFPA 1963 the authority having jurisdiction shall be permitted to designate the connection to be used. [13:6.7.1.1]
A.5.10.1.1
The purpose of the fire department connection is to augment the water supply, but not necessarily provide the entire sprinkler system demand. Fire department connections are not intended to deliver a specific amount of water.

5.10.1.2
The use of threadless couplings shall be permitted where required by the authority having jurisdiction and where listed for such use. [13:6.7.1.2]
5.10.1.3
A single-outlet FIRE DEPARTMENT CONNECTIONS shall be acceptable where piped to a 3 in. (80 mm) or smaller riser. [13:6.7.1.3]
5.10.2
FIRE DEPARTMENT CONNECTIONS shall be equipped with approved plugs or caps, properly secured and arranged for easy removal by fire departments. [13:6.7.2]
5.10.3
FIRE DEPARTMEN

Todd E Wyatt

6/20/2024 09:10:36 am

NFPA 15-2017
5.10 FIRE DEPARTMENT CONNECTIONS.
5.10.1
Unless the requirements of 5.10.1.1, 5.10.1.2, or 5.10.1.3 are met, the FIRE DEPARTMENT CONNECTIONS shall consist of two 2-1⁄2 in. (65 mm) connections using NH internal threaded swivel fitting(s) with “2.5–7.5 NH standard thread,” as specified in NFPA 1963. [13:6.7.1]
5.10.1.1*
Where local FIRE DEPARTMENT CONNECTIONS do not conform to NFPA 1963 the authority having jurisdiction shall be permitted to designate the connection to be used. [13:6.7.1.1]
A.5.10.1.1
The purpose of the fire department connection is to augment the water supply, but not necessarily provide the entire sprinkler system demand. Fire department connections are not intended to deliver a specific amount of water.

5.10.1.2
The use of threadless couplings shall be permitted where required by the authority having jurisdiction and where listed for such use. [13:6.7.1.2]
5.10.1.3
A single-outlet FIRE DEPARTMENT CONNECTIONS shall be acceptable where piped to a 3 in. (80 mm) or smaller riser. [13:6.7.1.3]
5.10.2
FIRE DEPARTMENT CONNECTIONS shall be equipped with approved plugs or caps, properly secured and arranged for easy removal by fire departments. [13:6.7.2]
5.10.3
FIRE DEPARTMENT CONNECTIONS shall be of an approved type. [13:6.7.3]

6.4.3* FIRE DEPARTMENT CONNECTIONS
6.4.3.1*
One or more FIRE DEPARTMENT CONNECTIONS shall be provided as described in this subsection.
6.4.3.2
FIRE DEPARTMENT CONNECTIONS shall not be required for the following installations:
(1) Systems located in remote areas that are inaccessible for fire department support shall not require a fire department connection.
(2) Large-capacity systems exceeding the pumping capacity of the fire department shall not require a fire department connection.
(3) Ultra-high-speed water spray systems shall not require a FIRE DEPARTMENT CONNECTIONS.
6.4.3.3
The number of outlets and size of the outlets and piping in the FIRE DEPARTMENT CONNECTIONS shall be sufficient to supply the water spray system demand.
6.4.3.4
The arrangement and other installation features of FIRE DEPARTMENT CONNECTIONS shall be in accordance with NFPA 13.

Dwight Havens

6/20/2024 10:04:49 am

I would start with the required flow and pressure to the system
needed to meet the minimum design flow and pressure at the point of connection of the FDC(s) to the system piping. Then i would look at how that flow and pressure can or will be met feeding from the site hydrant system, through the available fire pumps (or apparatus), through the LDH hose, and through the FDC piping and fittings to the point of connection of the FDC to the system piping. Can the available flow and pressure fed through the FDC(s) available meet the required flow and pressure for feeding the system in this manner? If yes, you are good, if no, is the owner or the AHJ actually requiring this? If yes, the means needs to be modified to meet the requirement. If no, get it in writing that the question has been answered.

Jack G

6/20/2024 05:36:27 pm

I m not sure where you are going with this.
First I d consult the Meyer fire fdc cheat sheet and lean towards the NFPA 13 and NFPA 14 notes on the cheat sheet as the water demand for your system may be more like a standpipe if it’s a large system or high density.
Secondly — review the 900 ft perimeter for high rise or large buildings, which require 2 fdc s. From different streets. Does your site— I am imagining an exposure system — may be large ( like large propane tank farms ) and fdc access from 2 or more streets or locations may be desirable.
A storz could be used ( consult ahj ) or 250 gpm for each 2.5 outlet ( per system demand) connection with checks / snoots for back pressure.
( on the fdc body) The fdc connections should also have check valves ( with fdc drain) on supply to system.
NFPA 15 may not be listed in your municipalities code index in the rear of the IBC — chat. 35. So consult the AHJ for their feedback.

RYAN HINSON

6/21/2024 11:50:25 am

Is your deluge system standalone, or one of several systems fed from a common header? How large is it? Is it inside or outside?

By definition, an FDC is typically meant as a 'supplement' to the water supply as referenced in NFPA 13 (2022) Section 3.3.79. This is reiterated in NFPA 15 (2022) Section 5.10.1.1 which states "the purpose of an FDC is to augment the water supply but not necessarily provide the entire sprinkler demand" and is further inferred in Section A.9.3.1 which states an FDC "should not be considered as a primary source of water supply for a water spray system".

NFPA 15 Sections 6.4.3 and A.6.4.3 provide direction on when an FDC is- or is not required and whether or not it needs to provide supplemental- or all necessary supply. NFPA 15 Section 6.4.3.4 directs one to follow NFPA 13 for FDC installation and arrangement. NFPA 13 Section 16.12.2 provides similar direction as that found in NFPA 15 as to when they are required. NFPA 13 Sections 16.12.3 and 16.12.4 also provide requirement for FDC sizing.

Ultimately, both final determination of whether the FDC needs to supply all flow and pressure to the system and the sizing and thread-type must be discussed with the AHJ and responding personnel.

Once this is known, the quantity of connections can then be considered based on previous comments or any of the following:
- NFPA 13 Section 16.9.7.5.1 or 16.14.5.1.1's requirements of 250 gpm per 2½" outlet,
- NFPA 20 (2022) Table 4.28(a) where approximate 2½" test header hose quantities are 250 gpm each of a pump's rating, or
- NFPA 14 (2016) Section 7.10.3.1 limits of 250 gpm per 2½" hose connection.

The location of the FDC should be sufficiently far away from the protected assets and accessible at all times in compliance with NFPA 15 Section A.6.4.3.1.

There are many manual industrial systems out there which are manual (as allowed per NFPA 15 Sections 3.3.24, 5.7.2.3, & 7.1) or semifixed (as defined in NFPA 11 (2021) Section A.3.3.17.5) which have no permanent connection to the supply which must have all required flow, pressure, and duration provided through the FDC such as is common on foam systems. In this case, hydraulic calculation and the necessary flow and pressure at the FDC is imperative to a properly functioning system.

Any system reliant on the FDC as the primary source needs to have posted flow and pressure requirements for the deluge system(s) it serves.

How is Number of FDCs Determined in NFPA 15?

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