Recent FDMA Developments

Summary of the “Report on the Review Meeting for Fire
Prevention Measures and Approach to Firefighting
Operations after the Warehouse Fire in Miyoshi Town,
Saitama Prefecture” (Part One)
Kensuke Kimura, Fire Prevention Division, FDMA
 Introduction
A warehouse fire incident which occurred in Miyoshi
Town, Saitama Prefecture, on February 16 (Thu.),2017 took an extended period of about 12 days until
full containment, due to the fire spreading inside thelarge-scale warehouse. After this serious incident, theFDMA in a joint effort with MLIT organized a “Review
Meeting for Fire Prevention Measures and Approach
to Firefighting Operations after the Warehouse Fire in
Miyoshi Town, Saitama Prefecture” consisting ofrespected individuals, to discuss the fire prevention
measures and the approach to firefighting operations
to be taken from now on, and examined measures thatwould prevent the spread of fire as well as efficient

firefighting activities so as to prevent a similar disasterin a large-scale warehouse in the future.
In this paper, I intend to summarize the “Report on the
Review Meeting for Fire Prevention Measures andApproach to Firefighting Operations after the
Warehouse Fire in Miyoshi Town, Saitama Prefecture”
created on June 2017.

It should be noted that the opinion portion of thispaper reflects my own personal view.

 Summary of the “Report on the Review Meeting for Fire Prevention Measures and Approach
to Firefighting Operations after the Warehouse Fire in Miyoshi Town, Saitama Prefecture”

Date and time

Outline of the warehouse fire in Miyoshi Town, Saitama Prefecture
OutbreakFebruary 16 (Thu.), 2017 (time is underinvestigation)

Recognition

February 16 (Thu.), 2017 at 09:14

Fire
suppression

February 22 (Wed.), 2017 at 09:30

Fullcontainment

February 28 (Tue.), 2017 at 17:00

Use

Number 1 (Article 14) of the Attachment to
the Order for Enforcement of the Fire
Services Act (Warehouse)

Structure

Reinforced concrete structure, partially steel
construction

Number of stories

2

Warehouse external viewThree stories above ground

Building area

26,977.99 m2

Gross floor area

71,891.59 m2

Chapter 1 Details of the Fire

Origin of fire

Scrap material room at the northwest cornerof the 1st floor of the warehouse

Cause of fire

Under investigation
2

Burnt floor area

About 45,000 m (under investigation)

Number of injuries

2 (1 severely injured, 1 mildly injured)

1. Outline of the building in question
This building is one of the large-scale distribution
warehouses that are recently increasing in number,and has a width of about 240 m and a depth of about
109 m, with a gross floor area of about 72,000 m2. Theinternal space of the building is mainly used for thestoring and sorting of products with little wall volume,and the height to the ceiling is also high, which as awhole creates a large space structure. The
circumference of the building has a structure with afailing to attain the required pressure and volume ofwater.
At 09:21, the public firefighters arrived and took overthe firefighting. Although at this stage, the scrap
material room was full of flames, the force of the fire
was quickly suppressed, and the fire did not spread toother areas of the 1st floor.

Conditions inside the scrap material room

small number of exits to the outside other than theloading docks which are used for the loading andunloading of products.
In the building, many conveyors have been installed toconvey the products. To connect vertically, there areconveyors which link the 1st and 2nd floor, and the
2nd and 3rd floor. For horizontal transfer, there arealso conveyors specific for each floor. There are many
employees working in the building for receiving,
sorting and shipping the products, and at the time of
the fire, there were 421 employees inside the building.
2. Outline of the fire and the initial response at thebusiness site
The origin of the fire was the scrap material room at
the northwest corner of the 1st floor of the warehouse.
The scrap material room is the place where the usedcardboard is collected from many places around thewarehouse and accumulated on conveyors. At theupper opening of the room (2nd floor), the end part ofthe conveyor is installed, allowing the collected
cardboard to be thrown down to the 1st floor throughthe opening and accumulated.
At about 09:00 on February 16 (Thu.) on the day of fire,
an employee of a partner company working in the
scrap material room discovered flames at thesoutheast corner of the room. At about 09:07, theregional alarm of the automatic fire alarm systemsounded. Although the person who discovered the fireand other employees tried to extinguish the fire using
fire extinguishers, the fire was not contained because
the burning was too strong.
At 09:14, an employee who was involved in the initialfire extinguishing attempt called the 119 emergency
number using a mobile phone.
After the automatic fire alarm system sounded, an
employee went to the Disaster Prevention Center andconfirmed the location of the automatic fire alarmsystem detector which had been activated on thedisaster display board and saw smoke through thecamera monitor, but failed to call the 119 emergency
number. Because the burning was so strong, twoemployees extended the hoses from nearby externalfire hydrants (2 units) individually and opened thevalves, but did not push the button to start the pump,

On the other hand, an employee working on the 2nd
floor sensed a burning odor at about 09:08, and soon
discovered flames coming from the opening above thescrap material room (2nd floor). It is estimated that theused cardboard on the 1st floor burnt rapidly and thestrong flames rushed to the 2nd floor through the
opening above the scrap material room.
The flames moving to the 2nd floor from the scrap
material room on the 1st floor is considered to haveburnt the inflammable materials near the opening
above the scrap material room (2nd floor) and thenspread horizontally on the 2nd floor. Although a fire
shutter was installed near the opening above the scrap
material room (2nd floor), the shutter was found tohave closure difficulties caused by its contact with theconveyor. Likewise, there were many closure
disabilities of fire shutters and closure difficulties
caused by contact with conveyors, etc. found on the
2nd and 3rd floors, which are estimated to haveprovided routes for the fire to expand in the earlystages.
Note that all 421 people who were inside the building
were able to evacuate outside through such means as
the use of wireless equipment and the collaboration ofevacuation guidance teams on each floor.

Chapter 2 Operation Results of Fire Shutters
1. Results of the fire shutters closing motion
The resultant closing performance of the fire shutters
is as follows based on a visual check during theon-site investigation after the fire. Of all the fire
shutters on the 2nd and 3rd floors which were burnt(total of 133 locations), 61 failed to operate, 23 haddifficulties caused by conveyors or others, and 4 were
unknown due to their collapse, which means thatabout 60% of the fire shutters were found to havefailed under normal conditions.
(1) Closure status of the 2nd floor
The wiring for the detectors that are interlocked withthe fire shutters are divided into series 1 and series 2.
The closure status of the fire shutters on the 2nd floor
was found to have exhibited the following incidents.
-

For series 1, all the fire shutters that were toconfigure fire-proof compartments including theroom containing the origin of the fire did operate
but failed to form compartments due to closure
difficulties caused by conveyors or other objects
and, in other fire-proof compartments, many fire
shutters did not operate.

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Those found in closure
statusRecent FDMA Developments

Front view<

<Fire shutters on the 3rd floor>

Side view<

Closure difficulty caused by conveyor>

Closure difficulty caused by objects>

Those failed to operate

Those found to have hadclosure difficulties<Fire shutters on the 2nd floor><Fire shutters on the 2nd floor>-<Fire shutter on the 3rd floor (did not work and collapsed)>

For series 2, many fire shutters had closure
difficulties due to conveyors or other objects, andmany shutters in the southeast part did notoperate.

(2) Closure status on the 3rd floor
The closure status of the fire shutters on the 3rd floor
was found to have exhibited the following incidents.
-

For series 1, many fire shutters did not operate.

-

For the southeast part of series 2, many fire
shutters did not operate.

(3) Items pointed out during the inspection
During the firefighting equipment inspection(November 2016), the fire shutters were also
inspected, and 22 locations were identified as having
fire shutter closure difficulties due to obstacles on the
2nd and 3rd floors. The exact problems identified wereanti-drop acrylic boards and anti-drop nets installed at
the crossing points of the fire shutters and conveyors
and were identified at 20 locations and 2 locations
respectively.
It should be noted, however, that these closure
difficulties were identified at the locations of theconveyor portions above the acrylic boards and nets,

4<Slippage caused by damage to the closure mechanism>and the identified problems are not considered to be
the direct cause.
2. Operation status of the automatic fire alarmsystemThe wiring for the building’s automatic fire alarmsystem is divided to series 1 and series 2.
The recording paper printed by the receiver shows thetime when the thermal detector in each alarm districtissued the alarm, the time when the smoke detector
for the fire shutters operated, and the time when thefire shutters operated. According to the records of the
security company who received the alarm, the time
recorded by the receiver is considered to be later than
the actual time by 7 minutes, and the time notations inthis section all show 7 minutes later than the actualtime.
The fire was recognized at 09:14 when the thermal
detector in the alarm district of the scrap material room
situated at the northwest corner of the 1st floor
detected the fire.
With regards to series 1 of the 2nd floor, multiple
thermal detectors detected the fire at 09:15 when thefire spread. For series 2, the start signals for the
shutters and the thermal detectors operated.

Series 1

Series 2

Verticalhole

Vertical
hole

2nd
floor

Southeast
part

ClosureClosure difficulties caused byconveyor
Closure difficulties caused by
objects

Series 1

Series 2

Not operated
Unknown due to collapse
Locations identified by theinspection

Verticalhole

Vertical
hole

3rd
floor

*“Not operated” includes cases where the shutters only partially closed as the result of fire damage to the closure mechanism.
*The normally closed types of fire prevention system installed in elevators and staircases are not described here.

For series 1, the transmission line developed a failure
at 09:17, and then the functionality of the transmission
line became unstable and was lost at 09:21, causing
the inability to transmit signals from the detectors to
the fire shutter relay devices, thereafter disabling thefire shutters.

In this building, 4 units of analog type detectors (allinstalled at vertical hole portions), and the analog
detectors installed at the upper location of the scrap
material room (2nd floor) are considered to have
impacted the failure of series 1.
Also, within the receiver, the blowing of the fuse which
formed part of the wiring for the fire shutters wastime-stamped at 11:23.

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Fire

Relay unit board

Top view of the warehouse (1st floor)

6

Series 2

Series 1 Series 2

Series 1

Relay unit board

At 09:14, thermal detector
At 09:15, smoke detector
operated.
operated.
Solid line: Walls and alarm districts covered by the automatic fire alarm system

Relay unit board

Receiver

1st
floor

At 09:16, the smoke detector interlocking with the fire shutter
operated.
Dotted line: Alarm districts covered by the automatic fire alarm system

Legend* The time notation is based on the automatic fire alarm system recording paper (estimated to be 7 minutes late).

Recent FDMA Developments

Top view of the warehouse (2nd floor)

7

Relay unit board

Series 2

Series 1 Series 2

Series 1

Relay unit board

At 09:15, smoke detector
operated.

Solid line: Walls and alarm districts covered by the automatic fire alarm system

At 09:14, thermal detector
operated.

Relay unit board

2nd
floor

Dotted line: Alarm districts covered by the automatic fire alarm system

At 09:16, the smoke detector interlocking with the fire
shutter operated.

Legend* The time notation is based on the automatic fire alarm system recording paper (estimated to be 7 minutes late).

Relay unit board

Top view of the warehouse (3rd floor)

8

Series 2

Series 1 Series 2

Series 1

Relay unit board

At 09:15, smoke detector
operated.

Solid line: Walls and alarm districts covered by the automatic fire alarm system

At 09:14, thermal detector
operated.

Relay unit board

3rd
floor

Dotted line: Alarm districts covered by the automatic fire alarm system

At 09:16, the smoke detector interlocking with the fire
shutter operated.

Legend* The time notation is based on the automatic fire alarm system recording paper (estimated to be 7 minutes late).

Recent FDMA Developments

North side

Central part

South side

Series 1

Series 2[Legend]

To district bells

To district bells

Transmission line
(heat-resistant wiring)

To fire shutters, etc.

To fire shutters, etc.

District bell control line
(heat-resistant wiring)

To fire shutters, etc.

To district bells

To district bells

To fire shutters, etc.

To fire shutters, etc.

Thermal detector
Smoke detector(To start the fire shutter)

Relay unit board

Analog detector

Origin of
the fire

General wiring

Thermal detector
Smoke detector(To start the fire shutter)

After wiring from south to north on the
1st floor, the wiring proceeded upward.

Simplified drawing created by abbreviating part of the systems in the design
drawing

DisasterPrevention Center
receiver

Relay part

To district bells

Thermal detector
Smoke detector(To start the fire shutter)

Fire shutter control line
(heat-resistant wiring)

Analog detector
Thermal detector
Smoke detector(To start the fire shutter)

Thermal detector
Smoke detector(To start the fire shutter)

Wiring of receivers

3. Wiring status of detectors, etc. interlocking
with fire shutters

all floors (the wiring system is not separated for eachfloor).

(1) Wiring of automatic fire alarm systems

While there are about 3,000 thermal detectors andabout 30 smoke detectors installed for the automatic
The wiring is divided into “series 1” for the north side
fire alarm system along with about 800 smoke
where the fire broke out, and “series 2” for the central
detectors for the fire shutters, all of these detectors
and south sides, and this wiring system is common tocause electric current to flow whenheat or smoke is detected. Current
also flows to a relay device in such
Analog detectors (4 units)
Transmission line
(Used for both automatic fire alarms and fire
event as a short circuit. For this reason,(Electric current is always
shutters)
flowing.)
the wiring is done using general wiringwith no heat-resistant capability. On
Relay devices
Detectors
for shutters
Automatic fire alarm thermal detectors
the other hand, in the fire-proof
about 3,000 units
Automatic fire alarm smoke detectors
compartments of the floor-penetrating
about 30 units
Fire shutter smoke detectors
about 800 units
parts in parts of the conveyors, 4Detectors
analog type detectors are installed,which transmit information on the
Relay devices for detectors
percentage of smoke as necessary.
General wiring
Since these detectors are always(Electric current flows only when
detecting heat or smoke.)
driving the current, they are wired
Fire receivers
using transmission cable integrating
the fire receivers, the relay devices forControl line
the detectors and the relay devices for
Fuses(Electric current flows only when thethe fire shutters. For this reason, whenswitches are engaged.)a failure such as a short circuit occurs
Switches
at a given location, the information of
Shutters
all connected detectors cannot betransmitted at all.
Shutters

Shutters

Switch control lines(Drives the switch of the shutter selected to be
shut down.)

Firesignals

Switch driving
signals

For the transmission of information, theinformation from the analog typedetectors, for example, is designed to
be sent to the fire receiver whichissues an instruction to a relay device
for a fire shutter, which in turn sends
the information to each fire shutter.

Electric current toenergize the shutter

Outline of wiring (line diagram)9

Recent FDMA Developments

Receiving line
(Disaster Prevention Center on
the 1st floor)

Transmission line
(Line to transmit information fromthe analog detectors)(2) Electric current did not flow to the relay devices forthe fire shutters, etc., preventing the switch starting
signal being sent.

Analog detectors

Relay devices forfire shutters

Switchstarting
signalShort circuit(1) The wiring isshort-circuitedforsome reason and thecurrent (transmission
information)isconcentrated in thelocation of the shortcircuit.

Control line
(Line to energize the fire shutters (power line))

Fuses(Installed in the receiver)Fire shutter is driven.

Outline of wiring (multi connection diagram)Also, in consideration of a short circuit caused by awiring mistake in the electrical installation, fuses are
installed in the receiver side of the control line which
supplies current to start the fire shutter not to damage
the receivers.
(2) Malfunction of fire shutters in series 1
Regarding the cause of many fire shutters in series 1
not functioning, it is considered that the wiring used fortransmitting information from the detectors (including
the analog detectors connected to the transmission
lines) was for some reason short-circuited in the fire,losing the entire functionality of the series as aconsequence, which prevented the signals from thedetectors being sent to the relay devices for the fire
shutters.
The scrap material room is structured so as to allow
the used cardboard transported on conveyors fromeach area of the entire warehouse to be thrown down
into the scrap material room through the opening
above the scrap material room (2nd floor) and beaccumulated in the room.

Heighttoceiling

Opening above the scrap
material room
(on the 2nd floor)

Heightof onefloor

Scrap material room
Positionof beams

Used cardboard

Status of piled-up used cardboard in the scrap material room
A concrete pillar was found to show
explosive fractures due to the fire.

Belt conveyor
motionAccording to the statement of the person who
discovered the fire, the used cardboard had
accumulated to a height of about half the height of thescrap material room on that day.
The fire in the room is considered to have flared up
due to the intake air supplied from the forklift exit (theexit point for used cardboard) which caused much of
the unfolded cardboard in the room to burn severely,with high temperature flames and heat bursting out
from the opening above the scrap material room (2ndfloor).

Near the opening above the scrap material room (2nd floor)

As a result, a reinforced concrete pillar on the 2nd floor
near the opening was severely heated and showed
explosive fractures.
Opening in the ceiling of the scrap material room on the 1st
floor

10

Inside the opening above the scrap material room
(2nd floor portion)

Status of wiring near the opening above thescrap material room (2nd floor portion)

Location where detectors
were installed (estimate)

Fracture of the protective pipe (steel pipe)
containing the transmission line for the smoke
detectors

Opening above the scrap material room

While the smoke detectors at the opening above thescrap material room (2nd floor) issued a fire signal(smoke density being equivalent to 10%/m), a starting
signal for the fire shutters (equivalent to a smoke
density of 17%/m) was not issued.
The smoke detector was configured to issue an alarmto the Disaster Prevention Center at a smoke densityof 5%/m, and to sound the district bell at a smoke
density of 10%/m.
It was confirmed that the detectors installed in theceiling above the scrap material room had fallen off,
and the protective pipe (steel pipe) containing thetransmission line for the smoke detectors was
fractured.
(3) Malfunction of fire shutters in series 2
Regarding the cause of many fire shutters in thesoutheast part in series 2 not functioning, it isconsidered that the control line to power theenergizing shutters was for some reason
short-circuited in the fire, blowing the fuse installed toprotect the receivers in the event of some failure suchas an electrical fire, causing the loss of functionality ofthe entire control line as a result.

(3) Transmission line remained functional andcontinued to send a switch-energizing signal to thefire shutters.

Receivers(Disaster Prevention Centeron the 1st floor)

Transmission line
(Line to transmit information fromthe analog detectors)

Analog detectors

Relay devices for the fire
shutters

Switch-energizing
signal(2) The fuse melted
due to the excessive
current.

(1) Excessive
current occurred
due to a shortcircuit of the wiring
for some reason.

Control line
(Line to energize the fire shutters (power line))
Short circuit

Fuses(Installed in the receiver)

Energizing the fire shutters

Outline of wiring (multi connection diagram)

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Recent FDMA Developments

4. Results of heat resistance tests for detectors
and wires
For the wiring in the compartments where analog
detectors were installed, the following items were to beinvestigated using experiments.
(1) What conditions create the risk of a short circuit?
(2) What measures are effective to prevent a shortcircuit?
For an outline and more detailed results of theseexperiments, readers are requested to read theexperiment report. However, as a result of reproducing
the wiring (heat-resistant wires) at the warehouse, andexperiments using heating detectors and part of thewiring as well as experiments using a refractory
furnace, the following became known.
-

No short circuits were found to occur when
conducting wires come into contact when thosewires are protected by heat-resistant coating,external coating or a steel pipe.
It is possible that a short circuit could happen whena conducting wire comes into contact with anotherconducting wire or with a steel object when such
wires are protected by heat-resistant coating andexterior coating but such coating has been meltedby heat.

-

5. Closure difficulties of fire shutters(1) Compartments created by fire shutters andintersecting conveyors
There are belt conveyors for carrying scrap material
and roller conveyors for carrying products installed in
the warehouse, some of which are installed tointersect at locations where the fire shutters would
come down (crossing the fire-proof compartments).
The outline of the belt conveyors is as follows.
-

-

-

-

(2) Receiving a fire signal (starts motion)(1) Normal stateFire shutter

Scrap material(empty cardboard
boxes)

MovablechuteFire shutter

Scrap material(empty cardboard
boxes)

They are used solely for “scrap material” such as
empty cardboard boxes and cardboard offcuts.
They are mainly installed in high positions. (3.0 m
maximum and 1.5 m at the locations where
workers would throw down the scrap material)
If there is a gap between the conveyors, it ispossible that any scrap material falling off theconveyors during transportation could cause
closure difficulties for the fire shutters.
The movable chutes which prevent the scrap
material falling off are designed to overlap thedownstream belt conveyor (the chutes are free tomove upward), hence the movable chutes have a
way to flip upward to get out of the way of the fire
shutter.
Since they use commercial power and do not haveany backup power, they do not work during a
power outage.
They use general wiring and have no heat
resistance.
(3) Motion completed

Movable chuteFire shutter(4) Fire shutter closing
Movable chute

Scrap material(empty cardboard
boxes)

Scrap material(empty cardboard
boxes)

Scrap material(empty cardboard
boxes)

Scrap material(empty cardboard
boxes)

Belt
conveyor

Belt
conveyor

Packages pass through the area
below the fire shutter.

Movablechute

Both upstream and downstream belt
conveyors stop.

Fire shutter

Belt
conveyor
Movable chute is lifted. The protruding
object is pushed back. The object on
the chute slides down.

Belt
conveyor
After the timer count (30 seconds
later), the fire shutter starts to close.

To prevent packages such as cardboard boxes falling off or being squashed, the movable chute overlaps the belt conveyor.

Outline of the belt conveyor(2) Receiving a fire signal (starts motion)(1) Normal stateFire shutter
SensorPackage

Roller conveyor

Movable roller

Packages pass through the area
below the fire shutter (sensor portion).

Outline of the roller conveyor

12

As soon as a
package passes
the sensor position,
the conveyor stops.

(3) Motion completed(4) Fire shutter closing

Fire shutter

Fire shutter

Fire shutter

Package

Package

Package

Roller conveyor
Movable roller
As soon as a package passes the fire
shutter position (sensor position), theconveyor stops.

Roller conveyor

Movable roller

After the package has moved on, themovable roller goes back down.

Roller conveyor

Movable roller

After the timer count (30 seconds
later), the fire shutter starts to close.

Remains of a package which
was on the pallet (estimated)
A gap exists between the partly
closed fire shutter and the floor.

Remains of a pallet used for carrying
packages by forklift (estimated)

Remaining items at a location where a fire shutter was to come down-

The exterior box that houses the control board
installed for each belt conveyor is neither
non-burnable nor flame-resistant.
In addition, the outline of the roller conveyors is asfollows.

-

The conveyors carry boxes and containers which
store products to be shipped out.

-

They are mainly installed in lower positions.

-

The packages are designed to flow on theconveyors with a certain distance between themand are controlled to take evasive action according
to the status of sensors installed at each end of theconveyor.

--

In consideration of the gaps between the roller
conveyors and the size of the packages, a
package should not fall through any gap, but a“movable roller” is installed to make thetransportation more stable.
The movable roller is normally energized, with theroller in the up position (the condition that could
present closure difficulties). When the movableroller is not energized (or during a power outage),the movable roller is at the retracted position
allowing the shutter to come down.

-

Since they use commercial power and do not haveany backup power, they do not work during a
power outage.

-

They use general wiring and have no heat
resistance.

-

The exterior box that houses the control board
installed for each belt conveyor is neither
non-burnable nor flame-resistant.

-Since the movable rollers are supported by air
cylinders, the roller will fall back down if the air
supply tube is burnt out.

During the on-site survey, the “movable chutes”
installed at the junctions of the conveyors were foundto malfunction, and there were multiple incidents
where they presented closure difficulties. On the other
hand, there were no incidents of the roller conveyors
causing closure difficulties.
Regarding the cause of the conveyors causing closure
difficulties, it is considered that any of the following
incidents could have happened to prevent themovable portions such as the “movable chutes” fromworking correctly.
-

They could not receive the fire signal correctly.

-

The power to energize the movable portion was
lost due to the power outage.

-

The movable portion was designed, when it did notwork, to remain in the condition which would
prevent the fire shutter closing.

(2) Remaining items at a location where a fire
shutter was to come down
At a location where one of the fire shutters was tohave come down, the on-site survey found theremains of some items considered to be packages
stored at that time. It is considered that thesepackages and some other items stored in thewarehouse left at this location where the fire shutter
was to come down provided one of the causes of theclosure difficulties.
(To be continued in the next issue)

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