ASHRAE Journal - July 2021 - 76

Reliability in Today's Motorized
Life-Safety Dampers
By Kent Maune, Life-Safety Product Manager at Ruskin®
Motorized fire, smoke and combination fire/smoke
dampers have come a long way since the 1970s
Originally, life-safety dampers were just standard commercial
control dampers with blade locks to hold them closed. Now,
they've evolved into advanced, rigorously tested devices.
The start of testing and standards
In the past, testing consisted of fire, 250-cycle and heatdegradation
tests. Because UL had no test procedure for
actuators, damper manufacturers listed the actuator used
in the test. Actuators did not have to operate under fire
conditions. Instead, manufacturers used a fusible link
connected to the damper blades and a shaft connected to the
actuator. During a fire event, the actuator disconnected from
the shaft, a spring closed the damper and a locking device
secured the blades. Because of the fusible link, full access
to a damper was required for visual inspection and testing.
Today, they have their own UL 555S (Fourth Edition)
test requirements, and there is a new test standard
for actuators and dynamic assembly operation.
The evolution of life-safety dampers
Modern life-safety dampers are specially designed to operate
during exposure to high temperatures and velocities. Now
they use a jackshaft with a solid connection that locks
the blades into position when the dampers are closed.
UL555 and UL555S are updated to meet today's building
HVAC and smoke-evacuation systems. Current standards
require damper and actuator assemblies to be cycle-tested
for a minimum of 20,000 cycles and subjected to a heatedair
dynamic-closure-and-operation test with a minimum
temperature of 250°F (121°C), a minimum air velocity of 2,400
fpm (10.2 m/s) and a system pressure of 4.5 in. wg (1.1 Pa).
UL procedures include spontaneous inspections at
manufacturers' facilities to ensure life-safety dampers are built
as tested, without modifications. Additionally, UL requires
installation instructions accompany each shipment of dampers.
Rigorous, remote testing is now possible
Nonmotorized dampers operating with fusible links require
visual inspection to determine if an issue exists with the damper.
Motorized dampers, with rigorous standards before shipment
to a job site and documented installation instructions from the
manufacturer, allow for remote testing of the damper after a
visual inspection. There are multiple options for remote testing:
* Control panel. A control panel can be hard-wired
directly to a damper with a momentary push button.
* Computerized fire-alarm panel. Requirements for
damper testing vary from country to country. For
example, in Europe, some countries require testing as
often as every 48 hours, performed by a computerized
fire-alarm panel that notifies users if something is wrong.
* Remote control. Similar to at-home devices to
control electronics remotely, a hand-held device is
available for testing UL-listed motorized dampers.
With remote-testing capabilities, it's not necessary to enter
ceiling cavities to test dampers, and the cost of testing can
be reduced by up to $500 a damper. NFPA 80 and NFPA
105 2019 versions will bring this option to the process as
well. Consult with the local Authority Having Jurisdiction,
as with all these new developments, for applicability.
A new era in accuracy, reliability and efficiency
This new remote testing method for fire and smoke dampers
is an efficiency tool for building owners and managers who
must document their inventory and the features of fireresistance-rated
and smoke-resistant assemblies, all while
keeping records of maintenance, testing and repairs.
Life-safety dampers are no longer glorified
control dampers, thanks to improved accuracy and
reliability, reduced tolerances and the development
of specialized actuators and testing equipment.
Visit ruskin.com to learn more about life-safety dampers
and how the flexible, time-saving solutions from
Ruskin make buildings safer and more comfortable.
ruskin@ruskin.com | 816-761-7476 | ruskin.com
http://ruskin.com http://www.ruskin.com
ASHRAE Journal - July 2021

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