Fire in block of flats which spread through the smoke ... directory/Regents... · through the smoke...
Transcript of Fire in block of flats which spread through the smoke ... directory/Regents... · through the smoke...
Fire in block of
flats which
spread
through the
smoke
ventilation
shaft
James GallSenior Fire Protection Inspector
Fire Engineering & Planning
Introduction
This presentation follows a serious fire in a residential block of
flats with a single staircase where significant fire spread
occurred from the floor of origin to other floors through the
natural smoke ventilation shaft system
The Building• The building is a seven storey purpose built block of flats
and part of a development of seven blocks of flats all of
similar designs.
• Development is located above a communal basement car
park.
• Natural smoke ventilation shaft system to achieve ventilation
of smoke from the common corridor/lobby areas on each
floor.
The Building- basement car park
The basement car park has natural cross ventilation
Single protected staircaseThe protected staircase has a lobby on each floor. At the head of the
stair there is a vent which opens on actuation of the smoke detector
at the head of the staircase or from a manual override switch.
Smoke vent shaft doors on flats corridors
operated by AFD
Smoke Shaft
Top
Bottom
(Permanent
opening into
car park for
all seven
blocks)
The fire
• 5 November 2016 approx 12:56 hours
• Flat 17 second floor
• Ignition source: Candle
• Bedding caught fire from candle
• Fire could not be extinguished by occupant
• Occupant evacuated the flat
• Fire spread into communal corridor- no self closer
located on flat entrance door!
• Smoke vent shaft doors opened on second floor and fire
spread on this floor
• Significant fire gases/heat spread up the smoke shaft
• Vent shaft doors opened on 6th, 4th and 3rd floors
• Heat/smoke damage to 6th & 4th floors, fire on 3rd floor
General floor layoutBed of origin
Common corridor
Smoke shaft
Lounge
Flat entrance door
This building design versus ADB
ADB 2007 design diagram
7 (current)
ADB 2000 design
diagram 12 note the
similarity to this
building in terms of
floor layout
Operational response
• Time Of Call 12:57
• 13:03 Enhanced PDA (4) sent due to multiple calls
• 13:20 Priority Assistance make pumps 5
• 13:28 Assistance make pumps 8
• 13:32 Incident confirmed as persons reported
• 14:06 INF- Fire now out 3 floors heavily smoke logged 8
BA’s in use, Offensive mode, Incident still persons
reported
• 14:35 INF – Incident now sectorised, Fire Search. Still
persons reported
• 15:18 INF- All persons accounted for
• 16:24 Incident reducing to 4 pumps
This building- second floor
Flat involvedKitchen 2nd bedroom
2nd Floor CorridorExit route smoke shaft to left Toward flat, smoke shaft to right
Fire Doors did their job!
Could have been worse!
3rd Floor Corridor
4th floor
5th Floor Corridor
Injuries to residents on sixth floor corridor
Two occupants from a sixth floor flat attempted to escape along the corridor
to the staircase by crawling on their hands and knees and holding a wet
towel over their faces.
Both burnt their hands and hair and inhaled smoke. They could not reach
the doors to the staircase at the end of the corridor and had to turn back.
Contributing Fire Growth Factors
• Bedroom fire door left open
• Flat entrance fire door left open
• Balcony door in lounge of flat open throughout the fire
(adjacent room to bedroom of origin)
• Smoke shaft opened by corridor smoke detector (AOV)
• Shaft functioned at most efficient immediately (open at bottom
and top)
• Bedroom window in flat failed (maximum ventilation to
compartment)
• Additional smoke shaft doors opened on other floors
• Windy conditions
Why did the smoke vent shaft doors
open on other floors?
• Testing carried out with artificial smoke on AFD devices.
• Without resetting the system multiple floor vents opened.
• Manual override devices also allowed multiple floors to be
opened.
• It is possible smoke leaked from the shaft onto upper
corridors and was picked up by AFD resulting in the shaft
doors opening.
Operation of these systems
Current guidance
These systems should ‘lock out’ or be programmed such that
only the vent on the fire floor opens all other vent doors should
remain closed even if smoke is subsequently detected on
other floors:
Paragraph 2.26 (b) (iv) of Approved Document B states that
only the vent on the fire affected floor should open and all
other storeys should remain closed;
Clause 14.2.2.4 of BS 9991 2015:
Clause 6.2.6.1 of the Guidance on Smoke Control to
Common Escape Routes in Apartment Buildings (Flats
and Maisonettes) produced by the Smoke Control
Association:
WYFRS programme of testing
• WYFRS Inspectors sampled eight blocks of flats with
smoke vent shafts to ascertain the cause and effect of
the systems;
• 80% of the blocks tested operated in a similar manner to
this building and therefore enforcement action is being
taken to rectify these deficiencies;
• From discussion with smoke vent & fire alarm engineers
there is some confusion in the industry as to how these
systems should operate;
• Where smoke vent shafts are present and have inlet
provision at the base, the inlet location is being checked
to confirm they are not open to a car park.
Maintenance and Testing
The main purpose of the visit is to have a test carried out of
any shaft smoke control system. For a shaft system:
• Actuate a lobby or corridor detector:
Check that the shaft vent opens only on that floor
and at the head and foot of the shaft if required.
• Without resetting the system proceed to another floor
and repeat the test, nothing should happen.
• Repeat as you feel necessary, to have a good sample.
• Again without resetting the system, find an override
switch and activate, nothing should happen.
• Have the system reset, any vents that opened should
close now.
• Check all smoke vent doors are close fitting and have
intumescent strips and smoke seals fitted.
National implications
• Some confusion in the industry in how these systems
should be programmed with inadequate cause and effect
testing.
Action so far
• BRE report (due to FOSI) sent to DCLG.
• Information brief sent through the National Operational
Learning Process.
• Addition into BS 7273-6 Code of practice for the
operation of fire protection measures – Interface
Systems.
• PAS 79 form to include cause and effect testing of these
systems.
Questions