Transcript Slide 1 - Hawaii NEBB - Northern California - Hawaii

Smoke Control Systems
Introduction and Commissioning
NEBB 2010 Semi-Annual Recertification
Presented By: Matt Donahue, P.E.
January 20, 2009
Agenda
• Codes related to Smoke Control and
Design Guides
• System Concepts
• Smoke Control System Information –
Using Documents
• Commissioning
Requirements and Standards
• International Building Code, Section 909
– Formerly 1994 & 1997 UBC Section 905
– California Building Code
• NFPA 92A - Standard for Smoke
Control Systems Using Barriers and
Pressure Differences
• NFPA 92B - Standard for Smoke
Management in Malls, Atria, and Large
Areas
Design References
• Design of Smoke Management Systems
–Klote & Milke
• ICC Guide to Smoke Control
–Evans & Klote
• NFPA 92A & 92B
• National Resource Council of Canada
Types of Systems Required
• The IBC requires systems to be
installed or provided for certain special
uses or occupancy types.
• IBC refers designer to Section 909.
• There are no specific types of systems
required by Code.
• Type is based on a Rational Analysis.
International Building Code
• Smoke Control Required For:
–Atrium (Section 404.4)
–Enclosed Malls when Atrium qualifications
are met (Section 402.9)
–Some Underground Buildings (Section
405.5)
–Smokeproof Enclosure design options
(Sections 1019.1.8 and 909.20)
–Stages, in lieu of roof vents (Section
410.3.7.2)
Other Requirements
• May be required by local (or state)
ordinances for all high-rise buildings carry-over from previous codes.
• Timed egress studies.
• Smoke protected seating allowances.
• Alternate Materials and Method
Requests.
Smoke Control System
Concepts Introduction
• It is important to recognize that these systems are not
intended for:
– Preservation of contents.
– Timely restoration of operations.
– Assistance in fire operations/overhaul.
• They are intended to:
– Manage where smoke goes and where smoke does not go.
– Maintain a tenable environment by limiting the spread of
smoke to areas outside the zone of origin (IBC 909.1). They
do not always maintain a tenable environment in the smoke
control zone of fire origin.
Smoke Control System
Concepts
• “Passive” vs. “Active” Smoke Control
• Smoke Barriers, Zone Boundaries and
Opening Protection
• Stairwell Pressurization – “Smokeproof”
Enclosures”
• Types of Mechanical Smoke Control
Systems
Passive vs. Active Control
• “Passive” uses building construction to
limit the spread of smoke in a structure.
• “Active” uses mechanical equipment to
control the spread of smoke in a
structure. Defined as mechanical
systems by Code and include
pressurization method, airflow method
and exhaust method.
Passive Smoke Control
• Previously known as “compartmentation”.
• When active is not feasible (small rooms,
no make-up air, unoccupied areas)
• Depends upon location within zone.
• May be separate zone or part of the
same zone (sub-zone).
• If entirely bounded within a zone, no
pressure difference can be obtained
between the active and passive zone.
Smoke Barriers
• Used to separate smoke zones: 1-hour
rated wall construction, outside wall to
outside wall.
• Leakage area ratios
–walls
–exits
–other shafts
–floors and roofs
–openings
0.00100
0.00035
0.00150
0.00050
determined by area
Opening Protection in Barriers
• Automatic closing (Self-closing OK in
many normally closed applications).
• Tight fitting smoke and draft control.
• 20-minute rating for doors.
• Gasketing - top, sides, and sill.
• Smoke/fire dampers at HVAC openings,
Class II minimum leakage rating, 250 oF
(121 oC) thermal release.
Opening Protection (cont.)
• Combination Fire/Smoke Dampers:
– When a fire damper is used within ductwork
on a smoke control system, the operating
temperature is required to be at least 50F
(10C) above the maximum smoke control
temperature or a maximum of 350F (177C).
– This is to ensure the damper will not close
prematurely when the system is operating in
the smoke control mode.
“Smokeproof” Enclosures
• Significant Changes to previous Code
approaches used.
• Multiple Design Options Now Available:
–Natural ventilation alternative (909.20.3)
–Mechanical ventilation alternative
(909.20.4)
–Stair pressurization alternative (909.20.5)
Natural Ventilation
• Open exterior balcony or vestibule with
opening 16 sq. ft. in area facing an open
area that is at least 20 ft. in width.
• Stair enclosure separated from building.
Mechanical Ventilation
• Stair Shaft Pressurization –
+0.10”w.c. (25 Pa) from stair to all
vestibules.
• Relief vent at top of stair shaft
adjusted to maintain +0.10” w.c.
pressure in stair shaft.
Mechanical Ventilation (cont.)
• Vestibule Ventilation – One air
change/minute supply with exhaust at
least 150% of supply.
– Engineered system sized to provide 90
air changes per hour serving up to three
vestibules simultaneously.
– Smoke trap in vestibule, ceiling at least
20” above door.
Mechanical Ventilation (cont.)
• Vestibule Ventilation (continued)
– Supply air within 6” of floor level.
– Exhaust air entirely within the smoke trap
and not more than 6” down from the top of
smoke trap.
– No dampers required in system, unless
engineered so.
Stair Pressurization
• Only in fully sprinklered buildings.
• Vestibules are not required.
• Stair Shaft Pressurization –
+0.15”w.c. (37 Pa) minimum up to
+0.35”w.c. (87 Pa) maximum to all
vestibules.
Stair Pressurization (cont.)
• Major Considerations:
– Beware of door opening force limitations!
– Consider maximum stack effect
pressures, temperature gradients.
– Tested with all doors closed.
– No relief vent required at top of shaft, but
may enhance system operation and
balance system operation.
– Difficult to achieve in tall buildings with a
single zone in stairway.
Ventilation Equipment
• Activated at each floor level at the entrance to
the “Smokeproof” Enclosure.
• Ventilation system to be separate from building
systems
• Standby power required.
Items to Consider: Suggestions:
1) Stack effect
2) Porosity of walls
3) Door leakage
4) Door opening forces
5) Climate
1) Pre-test before inspector arrives
2) Door sweeps may help
3) Multiple injection points ~7-9
floors max. for 1 injection point
4) Adjust fan capacities
5) Adjust barometric damper
Mechanical Smoke Control
• Pressurization is default design method in
IBC.
• Exhaust can be used with the approval of
the AHJ.
• When is one is better than the other?
– Exiting considerations.
– Building configurations.
– Zone boundaries.
Mechanical Smoke Control
• Typical Uses of Active Systems:
– Pressurization – enclosed spaces, office areas,
residential corridors, where no make-up air is
provided.
– Exhaust – large open spaces (atrium, mall,
etc.) where make up is available or the zone is
not completely bounded by walls.
– Air Flow – protection of openings that do not
have physical protection.
– Modified type systems.
Design Options
• IBC 909.6 “Pressurization Method” and
NFPA 92A - Enclosed spaces, pressure
differential developed for containment.
Pressurization Method
• Pressure difference across barrier at
least 0.05-inch water column (12 Pa)
for sprinkler protected buildings.
• Twice the maximum calculated
pressure differential produced by the
design fire in sprinkler protected
buildings.
• Maximum pressure dependent on door
opening forces.
Pressurization Method (cont.)
• Add up leakage area from construction,
openings, including doors, to determine flow
rate to achieve pressure differential.
– Q = 2610 A (ΔP)½
– where Q = Leakage Rate (cfm)
– A = Area of Openings (sq. ft.)
– ΔP = Pressure Difference (inch w.c.)
• Problems
– Building may be tighter than calculated
– Oversizing fans means additional pressure
– Balancing with stairs
– Door opening forces
Door Force Calculations
• The opening force for doors at smoke
zone boundaries is limited to no more
than 30 lbs. (Some jurisdictions limit the
opening force to no more than 15 lbs.).
• The opening force is determined by the
force to overcome the closing device and
the pressure against the door.
• The larger the door or the greater the
pressure difference, the more the
opening force will be.
• IBC 909.8 “Exhaust Method” and NFPA 92B Open spaces, smoke exhaust to maintain smoke
layer above people on highest occupied level.
Exhaust Method
• Useful for large enclosed volumes.
• Maintain smoke 6 ft. above highest
walking surface in the zone
(previously 10 ft.)
• Natural or mechanical supply equal
to or slightly less than exhaust (85%
is general rule of thumb).
Exhaust Method (cont.)
• Maximum velocity of air supply
toward the fire is limited to 200 fpm.
– May affect plume geometry and
increase air inducted into the plume.
• Plume types - must consider the
type:
– Axisymmetric
– Balcony spill
– Window
Make Up Air
• The IBC requires make up air to be provided
for exhaust method systems.
• Required to be introduced at a rate slightly
less than the exhaust rate and cannot exceed
200 feet per minute towards the fire.
• As indicated before, the typical rule of thumb
is to provide at least 85 percent of this make
up air either by mechanical or natural means.
The other 15 percent can be obtained
through infiltration (building leakage).
Make Up Air (cont.)
• Make up air for high volume rate systems
can be difficult to provide given building
geometry and configurations.
• An exhaust rate of 200,000 cfm requires up
to 850 square feet of free openings to meet
the 85 percent rule. That equates to 85
linear feet of 10 foot high openings!
Make Up Air (cont.)
• Make up air needs to be introduced below the
smoke layer. If an exhaust system is being
provided for a multi-level space (such as an
atrium) the make up air can be introduced at
multiple levels, thereby decreasing the impact of
the make up air requirements for any one level.
• The free area of a vent, grille, louver or door
opening needs to be included in the make up air
flow rate. Most grilles and louvers do not
provide 100 percent free openings. Even “bird
screens” can limit the free opening by as much
as 10 to 15 percent.
Airflow Method (cont.)
• Airflow cannot exceed 200 fpm.
• Problems:
– Must assume temperature of smoke.
– Not useful for large openings.
– Not useful for horizontal openings.
– 200 fpm velocity often exceeded.
“6 Air Change” Design
• In “purging” systems (which are not
smoke-control systems) with 6 air
changes per hour, air is not completely
replaced in 10 minutes.
– HVAC systems promote mixing of air.
– 37% of original air (smoke) remains due to
dilution and stirring.
• Detailed discussion in NFPA 92A,
Section A.5.3.3.6
Modified Systems
• Sometimes the building configuration
presents restrictions to meeting the
specific design criteria for any one of
the four prescribed methods. In these
situations, a “modified” approach may
be necessary.
Modified Airflow
• Below grade parking garages often do not
have sufficient height to allow the exhaust
method to work and the drive aisles are open
to the exterior to prevent practical use of the
pressurization method.
• The Modified Airflow approach has been
used under these conditions, which is
essentially a purge method approach that
limits the make up air to no more than 200
feet per minute at the openings to the exterior
or drive aisles.
• Not very scientific but has been used in many
jurisdictions.
Design Considerations:
• Each of the four prescribed methods of
smoke control have certain limitations.
Often these come to light during
commissioning of the systems.
• The following are some of the lessons
learned during these times.
Design Considerations:
• It is impossible to get a pressure difference from one
space to another if there is no make up air in the
adjacent space.
• Not all small rooms will have smoke tight construction,
even if confirmed during the design.
• Leakage rates given for construction walls, whether
leaky or tight will always differ in the field from
calculations.
• Horizontal sliding doors that have no bottom tracks do
not work well at a pressurization zone boundary.
• Many building materials thought to be air-tight will leak
if not painted or sealed.
• Air flow measurements at openings can often provide
interesting results.
Rational Analysis
• There is no set document that is to be used for
the Rational Analysis. Each jurisdiction may
require or allow something different.
• The IBC requires the Rational Analysis to include
at a minimum:
–
–
–
–
An explanation of the types of systems to be used.
The methods of operation.
The systems supporting them.
The methods of construction to be used.
Rational Analysis
• The Rational Analysis should include
– A description of each zone, including the zone
designation.
– The type or method of smoke control.
– The method to activate the system.
– A description of how the system will configure.
– A description of whether the system will be
dedicated or non-dedicated.
– The pass/fail criteria for each system.
– What devices and equipment will be monitored
and in what position.
Rational Analysis
• Small-scale drawings should be
provided that show the zone boundaries
and the zone designation.
• Pressurized exit enclosures, passive
zones or sub-zones should also be
shown on these drawings.
Rational Analysis
• The Rational Analysis should also include
information on how and what equipment will
be monitored.
• Dampers to be monitored and which positions
are monitored.
• Door monitoring, if required.
• How fans will be separated between uses.
• The design criteria for time to display the
various status indications.
Rational Analysis
• The Rational Analysis can be part of an
overall document, such as a Fire
Protection Report or it can be a
separate Smoke Control Report,
depending upon the requirements of the
local jurisdiction.
Rational Analysis
• An example of a combined analysis may
look like this:
Rational Analysis
• And the Small-Scale Drawings like this:
Smoke Control Equipment
•
•
•
•
•
Fans (909.10.1)
Ducts (909.10.2)
Dampers (716.3 and 716.5.5)
Power Systems (909.11)
Detection & Control Systems
(909.12)
• Firefighters’ Control Panel (909.16)
Firefighters’ Control Panel
• Multiple Zone Example, shows status
and control on a zonal basis only.
Firefighters’ Control Panel
• Single Zone Example, shows status and
control for each piece of equipment.
Firefighters’ Control Panel
• System Status Indication:
– Pilot-lamp-type indicators required in
909.16.1 (LED’s more commonly used—
more reliable, much longer life).
– Indication by each piece of equipment
(fans, dampers).
– Alternately for complex systems,
indication by single smoke zone of all
zone associated equipment.
Firefighters’ Control Panel
• System Control (Override) Capability:
– Manual switches by each equipment or by
whole zone.
– Don’t blow-up the duct!
Stay aware of what you are doing if you
throw any switch, anywhere, any time.
Commissioning
Special Inspection
• Section 909.18.8 requires all smoke control
systems to be tested by a Special Inspector.
– The Special Inspector shall have expertise in fire
protection engineering, mechanical engineering
and/or certification as air balancers.
• Special Inspection is to occur:
– During erection of ductwork and prior to
concealment for the purposes of leakage testing
and recording of device location.
– Prior to occupancy and after sufficient completion
for the purposes of pressure-difference testing,
flow measurements, and detection and control
verification.
Be Calm in the Chaos
Special Inspection
• Team approach utilizing combination
of:
– Fire Protection/Mechanical Engineers.
– Air Balance Personnel.
– Fire Alarm/Controls Companies.
• More common during annual retesting.
Special Inspection
• Expertise in multiple fields required.
• Team approach often used.
• Lead Agency with subcontractors,
subconsultants to fill out areas of
expertise.
– Observation of Builder’s Subcontractors.
Special Inspectors
• Responsible to certify that the system has been
installed in accordance with the approved design
documents, which are assumed to comply with the
Code.
• The Special Inspector is not the Designer. Do not
redesign the system. Where questions arise in the
design, they must be referred to the Designer.
• Don’t try to break the system, test to the designer’s
sequence of operation. Does the system work as
designed?
Plan for Testing
• Agree on performance goals.
– Contained in approved Rational Analysis.
– If not, develop a test plan before testing
begins.
• Confirm agreement with:
– Design Engineer/Architect
– Building and Fire Inspection Authorities
– General Contractor
– All Subcontractors
Plan for Testing
• Schedule test time, including time of
day, days of the week.
• Keep the AHJ informed.
• Keep the Client informed.
• Keep the Contractor informed.
Inspection Sequence
•
•
•
•
Detailed device inspections.
Subsystem operation tests.
Full system functional tests.
Air flow/pressure differential verification.
Early Stage Inspection Item
• Duct leakage:
– Allowed 5% of fan capacity at 150% static.
– Test duct work in segments if too large or
concealment is imminent.
• Usually done by the Air Balance firm.
Check Devices (Elements)
• Fans – tag number, capacity, power,
speed, rotation, service rating, VFD
settings, HOA bypass.
Check Devices (Elements)
• Fire & smoke dampers - operation,
speed, installation, type, location,
power.
• Doors - label, operation, location.
• Smoke barriers - leakage, integrity.
Check Full System Operation
• Sequence of events.
• Control Priorities—Automatic and
Manual Overrides.
• Operability of other system
components in alarm conditions.
• Emergency power.
Functional Testing
• Pressure differential/exhaust air flow
measurements - includes fan data.
Functional Testing
Pressure Tests
• Pressure gauges:
–Lack the accuracy required to measure
system performance.
• Inclined manometer:
–Specified in IBC, not very accurate.
Pressure Tests
• Transducers:
–Equipment is calibrated to a known source.
–Commonly used by air balance personnel.
Door Opening Forces
• Verify door opening forces on all
or representative sample of
doors at zone boundaries,
including stair doors, to confirm
opening force does not exceed
the allowed door opening force.
Will likely require adjustments to
closers in some cases.
• Test apparatus can be easily
obtained but can also be easily
lost, so buy many.
Flow Rate Measurement
• Flow hood.
• Velocity – traverse, pitot tube.
Passive Barrier Testing
• Listed blower door
assemblies.
– Pressurize room and compare
actual leakage to calculated
allowable leakage rate at the
observed pressure.
• Configure HVAC to pressurize
space.
– Engineer may provide table of
allowable leakage rates at
varying pressure differentials.
Passive Barrier Testing
• In general, if the room is ready
to test it should pass and that
most rooms have actual
leakage less than allowable by
up to 50 percent.
• When testing representative
sample of rooms, choose rooms
for both sides of building.
• Equipment is usually calibrated
with reference charts to be
tested at 0.05-inch water
column.
• When room is too large, multiple
fans or door blowers can be
used.
Test Methods - Reflect Design
• Systems are designed to manage
where smoke goes.
• Systems are not designed to provide
tenable conditions in the area of fire
origin.
• Smoke tests, if used, should
demonstrate air flow direction of the
system considering the buoyant nature
of smoke.
Other Test Methods
• Chemical smoke, tracer gas and real
fire tests.
– Limited value in evaluating certain system
performance.
– Validity as methods of testing a smokecontrol system is questionable.
– Detailed discussion in NFPA 92A, Section
A.5.3.3.6 and NFPA 92B, Section 5.3.6.2.
• Some jurisdictions will still require it.
Chemical Smoke Products
“Cold” Smoke Test
Documentation
• Complete test records are essential.
• Provide a copy of all test documentation
to the Special Inspector:
– Copy of deficiency lists provided to
General Contractor
– Copy of interim and final air balance
reports.
– Complete fan start-up information.
Documentation – Daily Report
The daily report
provides specific
information on the
areas and system
components tested,
whether there were
any deficiencies
noted and resolved
or left outstanding.
Documentation – NCR
The NonConformance Report
identifies outstanding
issues or deficiencies
noted during the
course of testing and
also provides a
means to officially
notify the Contractor.
Deficiencies should
be specifically
identified.
Documentation - Fans
Documentation – Passive Barriers
Additional Inspection
Guidance
• National Environmental Balancing Bureau
(NEBB).
• Associated Air Balance Council (AABC).
• American Society of Heating, Refrigerating
and Air Conditioning Engineers (ASHRAE).
• Society of Fire Protection Engineers (SFPE)
• Sheet Metal and Air Conditioning Contractors
National Association (SMACNA).
Thank You For Your Time!
Questions?
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(925) 938-3550