understanding fire & smoke damper application...
TRANSCRIPT
Understanding Fire & Smoke Damper Application Requirements
ASHRAE St. Louis Chapter Tech Session February 9, 2015
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Stephen W. Duda, PE, Fellow ASHRAE ASHRAE-Certified HBDP, HFDP, BEAP
Senior Mechanical Engineer Ross & Baruzzini, Inc. [email protected]
Engineering & Architecture St. Louis / Miami / Indianapolis / Philadelphia / New York Columbia, IL / Hamden, CT / Toronto
Learning Objectives for this Session
1. Learn and understand the four different types of Fire-Rated wall construction in the IBC.
2. Learn and understand the three different types of Smoke-rated wall construction in the IBC.
(Hint: none of them is called a “Smoke Wall” – no such thing).
3. Learn where an HVAC duct cannot penetrate rated construction at all, not even with a life safety damper.
4. Learn where and when to apply fire dampers, smoke dampers, or combination dampers.
5. Learn some tips and tricks to avoid applying unnecessary fire or smoke dampers.
6. Learn the importance of delving into Chapter 7 of the IBC – it is not just the Architect’s domain.
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Tech Session Outline • Introduction
– Why Learn this Stuff – Codes Referenced
• Fire-Rated Construction – Fire Walls – Fire Barriers – Shaft Enclosures – Fire Partitions
• Smoke-Rated Construction – Smoke Barriers – Smoke Partitions – Hospital Corridor Walls
• Design Tips #1 through #8
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The Engineer’s Notebook Series
• Established (in its current format) by Fred Turner, then-editor of the ASHRAE Journal, beginning October 2013.
• Rotating system of Four Senior Mechanical Engineers in the day-to-day practice of HVAC Engineering; all ASHRAE Fellows.
• Each author contributes 3 columns per year. – Steven Taylor (Taylor Engineering, Alameda, CA). – Stephen Duda (Ross & Baruzzini, St Louis). – Kent Peterson (P2S Engineering, Long Beach, CA, Presidential Member) – Daniel Nall (Syska Hennessy, New York City)
• We hope you are reading it and are finding it useful. • This Tech Session is adapted from the July 2014 column . . .
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Introduction • Why Learn this Stuff? It is in the Architect’s part of the Code!
• Some HVAC engineers and designers are uncertain where to put fire dampers and smoke dampers.
• Even some Architects don’t fully understand the differences between partition types.
• This leads some to specify fire and smoke dampers where they really are not required.
• Others may fail to specify fire and smoke dampers where they are required, setting up a potential life safety hazard.
• So we owe it to our clients and the “Average Jane/John Doe” who occupy our buildings and trust our expertise.
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Introduction • This Summary is based on the 2012 Edition of the
International Building Code.
• The 2009 edition of IBC has the same requirements but with different paragraph numbering.
• Most jurisdictions in our region of practice enforce one or the other of the above code editions.
• NFPA 90A is also used for guidance.
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Fire-Rated Construction • There are four types of fire-resistance rated walls.
• Before you can know what type (if any) fire damper to use, you first must know which of the four types of walls you have.
• To learn about the 4 types, see IBC Chapter 7.
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1. Fire Walls • Major separation walls between buildings – or – to divide one
building into separate buildings.
• This is the most restrictive of the various types of fire-rated walls, and is rather rare on most building projects.
• Most fire-rated walls within buildings are not this extreme.
– So don’t refer to all rated construction as “Fire Walls”!!
• A Fire Wall actually allows you to treat the spaces on opposite sides of the wall as totally separate buildings.
• Usually three to four-hour rated, and are usually structurally independent.
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1. Fire Walls • You cannot run a duct or air transfer opening through a Fire
Wall located on a property or lot line – not at all – not even with a fire damper.
• If you run a duct or air transfer opening through a Fire Wall located within a building, use a three-hour fire damper.
2012 IBC Section 706
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2. Fire Barriers • Medium-rating level of the various types of fire-rated walls.
• Examples:
– Exit passageway enclosures
– Atrium boundaries
– Stairwell enclosures
– Separations between occupancies in a mixed-use building
• Usually two-hour rated, but there are exceptions, so check with the architect.
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2. Fire Barriers • You cannot run a duct or air transfer opening through an exit
passageway enclosure or stairwell enclosure (not at all; not even with a fire damper) unless that duct is for the purpose of independent stairwell pressurization.
• If you run a duct through other types of Fire Barriers, use a 1½-hour fire damper.
• Exception: If the fire barrier is only one-hour rated, and if the building is fully sprinklered, and if the system is fully ducted (not an air transfer opening), then you don’t need a fire damper.
2012 IBC Section 707
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3. Shaft Enclosures • Usually two-hour rated.
• Shaft enclosures are not required if all of the following are true: (a) fully-sprinklered building, (b) not a hospital or prison, (c) connects only two floors and no more.
• In the above case, use a 1½-hour horizontal fire damper at the floor line.
• Other than the above case, shaft enclosures are required anytime a duct travels vertically floor-to-floor.
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3. Shaft Enclosures • A 1½-hour fire damper and Class I or II smoke damper (or
combination damper meeting both requirements) is required at each penetration of a shaft enclosure.
• If the shaft does not extend all the way to the bottom of the building, some Code officials may allow you to place a horizontal fire/smoke damper at the floor level where the duct emerges from the bottom of the shaft.
• Other Code officials will rule against this and will instead require that the shaft be extended down into the ceiling cavity of the floor below, so that your duct can emerge from the side of the shaft with a vertical fire/smoke damper.
2012 IBC Section 713 14
3. Shaft Enclosures
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Design Tip #1 • You can avoid the fire/smoke damper at the shaft penetration
if all of the following are true . . .
• You have a vertical shaft with exhaust ducts entering the shaft on every floor (such as in a high-rise hotel or dormitory),
• You build steel sub-ducts that extend vertically upward into the vertical riser by at least 22 inches,
• And if there is a continuous flow of air upward to the outdoors (e.g., the exhaust fan is on the roof and is always on).
• In some jurisdictions, the fan must be on emergency power for this exception to qualify.
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Design Tip #1
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Design Tip #2 • In those cases where horizontal fire dampers at a floor
penetration are permitted . . .
• Most manufacturers require that the damper be supported by and framed with a concrete floor; the dampers are not listed to be supported by gypsum board.
• So you must coordinate with the structural engineer to provide an opening in the concrete floor sized precisely for the damper plus space for expansion and contraction as required by the damper listing.
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4. Fire Partitions • Minimum-rating level of the various types of fire-rated walls.
• Usually one-hour rated.
• Examples:
– Corridor walls
– Tenant-separation walls in a multi-tenant building
– Walls dividing dwelling units in multi-family housing.
• Note that corridor walls in most fully-sprinklered buildings are not required to be rated at all (IBC ¶1018.1).
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4. Fire Partitions • If all of the following are true, then you don’t need a fire
damper (IBC ¶717.5.4, Exception #4):
– A given fire partition is not more than one-hour rated
– The building is fully sprinklered
– The system is ducted (not a transfer opening)
• Otherwise, in non-sprinklered buildings and/or in transfer openings, use a 1½-hour fire damper.
2012 IBC Section 708
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Smoke-Rated Construction • There are three types of smoke-resistance rated walls.
• Before you can know what type (if any) smoke damper to use, you first must know which of the types of walls you have.
• To learn about the 3 types, see IBC Chapter 7.
• Most importantly – there is no such thing as a “Smoke Wall” – the term simply does not exist within the context of building codes.
• It is important to use the correct terminology.
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A. Smoke Barriers • Found in hospitals and prisons, and are used to completely divide a
building floor into two compartments.
• A tell-tale sign of a smoke barrier on a hospital floor is to look for a double opposite-swing door in the corridor; that door will be on the smoke barrier wall.
• In a hospital, every floor that features patient care or patient sleeping rooms (as opposed to floors that are exclusively administrative or educational) must have a smoke barrier that runs straight (or reasonably close to straight) across the entire floor, from one exterior wall to the other, that divides the floor into two distinct halves.
• Smoke Barriers are a more restrictive classification than Smoke Partitions.
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A. Smoke Barriers • A Class I or II smoke damper is required at each duct
penetration of a smoke barrier.
• Smoke barriers are also automatically one-hour fire partitions, so go back a few slides to determine a possible fire damper requirement.
• For HVAC reasons, architects must use the term ‘Smoke Barrier’ only where they truly apply. If the terminology is used correctly, we can eliminate a lot of unnecessary smoke dampers.
2012 IBC Section 709
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B. Smoke Partitions • Used to enclose storage rooms, trash rooms, boiler and
furnace rooms, and similar rooms that have a higher-than-average chance of fire.
• These are not nearly as significant as smoke barriers.
• Smoke partitions are intended to contain the smoke and heat resulting from a fire just long enough to activate sprinklers or smoke detectors quickly.
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B. Smoke Partitions • A Class I or II smoke damper is required at each air transfer
opening in a smoke partition.
• Nothing is required in ducted penetrations of smoke partitions, and this is where I most often see over-specification.
• Ducted penetrations of smoke partitions do not require smoke dampers.
2012 IBC Section 710
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C. Hospital Corridor Walls • Corridor walls in a hospital are required to form “barriers to
limit the transfer of smoke” but are not smoke barriers.
• Corridor walls in a hospital are actually considered smoke partitions, not smoke barriers. This is another area where some designers use smoke dampers unnecessarily.
• No dampers are required in ducted penetrations of smoke partitions, including hospital corridor walls.
2012 IBC Section 407.3
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Design Tip #3 • Do not put any dampers in Type 1 grease exhaust and clothes
dryer exhaust systems (IBC ¶717.5.3).
• If your hood or dryer exhaust duct crosses a rated wall or floor, then instead of a damper you must encase the duct itself in a rated enclosure such as a fire-rated gypsum board shaft or a listed/labeled fire-wrap insulation material.
• Or use sub-ducts in lieu of dampers at vertical shafts (see Design Tip #1).
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Design Tip #4 • Fire dampers are available in 1½-hour and 3-hour ratings.
• Those are generally the only two choices.
• Use a 1½-hour fire damper in 1-hour or 2-hour walls.
• Use a 3-hour fire damper in 3-hour or 4-hour walls.
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Design Tip #5 • Fire dampers are available as “static” or “dynamic”.
• Static fire dampers are only tested to close without air moving in the duct.
• Dynamic fire dampers are tested to close with or without air moving in the duct.
• I recommend you always specify dynamic fire dampers since the cost difference is trivial.
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Design Tip #6 • Fire damper Frames:
• Frame A means the blades, in the open position, partially block the free area of the duct.
• Frame B means the blades, in the open position, are completely outside the free area of the duct.
• Frame C is for round ducts.
• These frame types apply only to curtain-type fire dampers, not to multi-blade type dampers like most combination fire/smoke dampers.
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Design Tip #6
Frame A
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Frame B
Frame C
Design Tip #7 • Fire dampers and smoke dampers must be accessible for
service.
• If reaching inside the duct is necessary (for example, to re-open a closed fire damper) then you must provide a duct access door and a ceiling access panel or an accessible ceiling type.
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Design Tip #8 • If a fire or smoke damper placement will interfere with the
operation of an engineered smoke exhaust system (such as for an atrium), approved alternate protection shall be used (IBC ¶717.2.1).
• What I have usually done in this case is to specify a remotely resettable fire/smoke damper addressable by the fire department at a fire command center.
• For buildings where engineered smoke control is required by code, smoke damper open/closed status indication is required for all dampers that affect the proper operation of the smoke control system.
• To be continued . . . at tonight’s 2nd Presentation. 35
Conclusion / Wrap-Up • Know the four different types of Fire-Rated wall construction
in the IBC and use the terms correctly.
• Know the three different types of Smoke-rated wall construction in the IBC and use the terms correctly.
• There is no such thing as a “Smoke Wall”.
• A ducted penetration (i.e., not a transfer opening) in a one-hour fire partition in a fully-sprinklered building does not require a fire damper.
• Ducted penetrations (i.e., not a transfer opening) in a smoke partition does not require a smoke damper.
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Bibliography • ICC. 2012. International Building Code. Chicago: International
Code Council, Inc.
• NFPA. 2012. Standard 90A Standard for the Installation of Air-Conditioning and Ventilating Systems. Quincy, MA: National Fire Protection Association.
• Duda, Stephen. 2014. Fire & Smoke Damper Application Requirements. ASHRAE Journal 55 (7), July issue. Atlanta: ASHRAE, Inc.
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