Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
---
title: Fire and Smoke Dampers
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## Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
−## Where the AHJ has adopted an edition of a code or standard that differs from the edition cited here, the AHJ-adopted edition shall govern. {note}
+## Where the AHJ has adopted an edition of a code or standard that differs from the edition cited here, the AHJ-adopted edition shall govern.
| Standard | Title |
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## Smoke dampers shall be required where ducts and air-transfer openings penetrate smoke barriers and smoke partitions, per IBC Section 717.3.3.
−## The damper required at each penetration shall be coordinated with the rated assembly it serves; the assembly rating, not the duct, determines the damper requirement. {note}
+## The damper required at each penetration shall be coordinated with the rated assembly it serves; the assembly rating, not the duct, determines the damper requirement.
# Fire Rating {toc}
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## The 1.5-hour rating is the correct default for the large majority of commercial assemblies, which are rated 1 to 2 hours. The 3-hour damper is reserved for 3-hour fire walls and floors and is both less common and more limited in available listed sizes. {note}
+## The damper's fire-protection rating shall be specified based on the fire-resistance rating of the assembly in which the damper is installed.
+
```datasheet
label: Fire-protection rating
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## Specifying a static-rated damper in a dynamic (fan-on) system is a recurring and dangerous error. A static damper is not tested to overcome airflow and may stall partly open or fail to seal, defeating the rating at exactly the moment it is needed. Confirm the fan-shutdown sequence before selecting a static device. {note}
−## The dynamic rating, where required, shall be not less than the maximum system airflow velocity and static pressure at the damper at the time of actuation. {note}
+## The dynamic rating, where required, shall be not less than the maximum system airflow velocity and static pressure at the damper at the time of actuation.
```datasheet
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## Specifying triple-vee-groove blades for a high-velocity duct produces a non-listed installation; the blade style must match the velocity range of the UL listing. {note}
+## The damper blade style shall be specified consistent with the damper type and the duct velocity at the point of installation.
+
```datasheet
label: Blade style
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# Performance Ratings {toc}
−## Velocity and pressure ratings shall be verified against the duct system's design conditions; the listed rating of the damper shall equal or exceed the actual airflow velocity and static pressure at the damper. {note}
+## Velocity and pressure ratings shall be verified against the duct system's design conditions; the listed rating of the damper shall equal or exceed the actual airflow velocity and static pressure at the damper.
## Curtain-type static dampers shall be applied within their listed velocity, typically up to 2,000 fpm.
## Multi-blade dynamic dampers shall be applied within their listed velocity, typically up to 4,000 fpm with airfoil blades.
−## The damper's listed pressure class shall equal or exceed the duct system design pressure; most listed assemblies are rated to 4 in. w.g., and the 6 in. and 8 in. w.g. classes are reserved for special high-pressure applications. {note}
+## The damper's listed pressure class shall equal or exceed the duct system design pressure; most listed assemblies are rated to 4 in. w.g., and the 6 in. and 8 in. w.g. classes are reserved for special high-pressure applications.
```datasheet
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## Class I leakage shall be provided for smoke dampers in smoke barriers and for any smoke damper that is a component of an engineered smoke-control system.
−## Specifying Class II or Class III leakage where an NFPA 92 smoke-control design assumes Class I will cause the system to fail its performance verification; confirm the leakage class against the smoke-control design before selecting a lower class. {note}
−
```datasheet
label: Smoke damper leakage class
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```
+## Specifying Class II or Class III leakage where an NFPA 92 smoke-control design assumes Class I will cause the system to fail its performance verification; confirm the leakage class against the smoke-control design before selecting a lower class. {note}
+
# Release and Actuation {toc}
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## Fusible links shall be rated for the maximum expected ambient temperature at the damper while reliably releasing at the lowest practical temperature above that ambient.
−## A 165°F (74°C) fusible link shall be the default for standard HVAC service.
−
−## A 212°F (100°C) fusible link shall be used in elevated-ambient locations such as near kitchen exhaust or unconditioned spaces.
−
−## A 286°F (141°C) fusible link shall be used only for special high-temperature applications where the lower-rated links would nuisance-release.
−
−## Specifying a higher-temperature fusible link than the ambient requires delays actuation and is inappropriate in normal office HVAC; 165°F is the correct default unless the ambient genuinely justifies a higher rating. {note}
−
```datasheet
label: Fusible link rating
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```
+## A 165°F (74°C) fusible link shall be the default for standard HVAC service.
+
+## A 212°F (100°C) fusible link shall be used in elevated-ambient locations such as near kitchen exhaust or unconditioned spaces.
+
+## A 286°F (141°C) fusible link shall be used only for special high-temperature applications where the lower-rated links would nuisance-release.
+
+## Specifying a higher-temperature fusible link than the ambient requires delays actuation and is inappropriate in normal office HVAC; 165°F is the correct default unless the ambient genuinely justifies a higher rating. {note}
+
## Actuators for smoke and combination dampers shall be spring-return, fail-closed, so that loss of power or signal drives the damper to the safe (closed) position.
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## Breakaway connections shall not be rigidly welded, screwed, or otherwise fixed in a manner that would prevent the duct from releasing from the sleeve.
−## Where the system design pressure or velocity exceeds the limits of a breakaway connection, a rigid connection listed for that condition shall be used as permitted by the damper listing. {note}
+## Where the system design pressure or velocity exceeds the limits of a breakaway connection, a rigid connection listed for that condition shall be used as permitted by the damper listing.
# Access Doors {toc}
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# Round and Oval Duct Applications {toc}
−## A combination damper listed for rectangular duct is not interchangeable with one listed for round or oval duct. Where the duct system includes round or oval runs through rated assemblies, round-listed assemblies shall be separately specified rather than forcing a rectangular damper into a transition. {note}
+## A combination damper listed for rectangular duct is not interchangeable with one listed for round or oval duct. Where the duct system includes round or oval runs through rated assemblies, round-listed assemblies shall be separately specified rather than forcing a rectangular damper into a transition.
## Round or oval duct penetrations of rated assemblies shall be protected by dampers UL-listed for round or oval duct service in the installed orientation.
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## Multi-blade damper section sizes shall not exceed the maximum size of the individual UL-listed product.
−## Multi-section (mulled) assemblies shall be furnished and installed only in the frame configuration covered by the manufacturer's listing. {note}
+## Multi-section (mulled) assemblies shall be furnished and installed only in the frame configuration covered by the manufacturer's listing.
# Testing {toc}
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## Each smoke and combination damper shall be cycled from the control interface to confirm the actuator drives the damper fully closed on signal and reopens on restoration.
−## Smoke dampers serving engineered smoke-control systems shall be verified to achieve their specified leakage class as part of smoke-control system acceptance under [[sync/smoke-control-systems]]. {note}
+## Smoke dampers serving engineered smoke-control systems shall be verified to achieve their specified leakage class as part of smoke-control system acceptance under [[sync/smoke-control-systems]].
## Any damper that fails to close fully, seal, or reset shall be corrected and retested before acceptance.
## Acceptance-test results shall be recorded for each damper and included in the closeout submittals.
−## Following installation, the building's periodic inspection and testing program shall follow the schedule of NFPA 80 (§19.4) for fire dampers and NFPA 105 (§6.5) for smoke dampers: an initial test one year after installation, then at intervals of four years for standard occupancies and six years for hospitals. {note}
+## Following installation, the building's periodic inspection and testing program shall follow the schedule of NFPA 80 (§19.4) for fire dampers and NFPA 105 (§6.5) for smoke dampers: an initial test one year after installation, then at intervals of four years for standard occupancies and six years for hospitals.
```datasheet
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- Spare actuators (each type/voltage used)
```