SR Products ETL121375 Nominal Temperature Rating User Manual

SR Products Hardware

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The Electro Thermal Link [ ETL® ] is a multi-purpose, dual responsive fusible link I release device. The

fusible link portion functions identically to an ordinary fusible link - ambient temperature nearing the rated
temperature causes the fusible alloy to melt, allowing the link halves to separate. The ETL® can also be
actuated by an electrical impulse. A 0.2 ampere minimum trip current applied for 50 millisecond minimum
duration starts an irreversible chemical reaction that melts the fusible alloy and causes link separation in 12 to
20 seconds at standard temperature. The ETL® was designed to substantially improve life safety and minimize
property damage by providing both ordinary fusible link response in the event of fire along with the capability to
instantaneously respond to any type of fire, smoke, infrared, light detector (etc.) capable of supplying a short
duration current impulse. The design allows for ETL® substitution or retrofitting of ordinary fusible links and
other actuators or release devices installed in: dampers; doors; roof hatches; towers; extinguishing systems,
and inert chemical or gas release systems. An inherent major advantage of the ETL® over other products is
the dually redundant dormancy – it draws no current and stays inertly in place until actuated, then functions
and separates in seconds. The ETL® is designed and intended FOR INDOOR (or sheltered) DRY USE ONLY.


The 375º F ETL® is a fusible link / release device with a 375º F (190º C) nominal temperature rating

and a 40 pound maximum continuous - 7 pound minimum continuous tensile weight rating at standard
temperature. Additionally, it contains a bridgewire initiated pyrotechnic heating element requiring a fifty (50)
millisecond minimum duration all fire current of 200 milliamperes (0.2 ampere) within a voltage range of 6-30
VAC/DC (NEC Class 2, low voltage). The fusible link portion is a nominal 1” (25.4 mm) X 3 ⅛ (79.4 mm) X ½”
(12.7mm) envelope with ½” (12.7 mm) square reinforced openings at the ends to allow attachment of “S”
hooks, straps, or other attachments. An 11/16” (17.3mm) diameter x 1 ¼” (31.7mm) protruding cylinder houses
the pyrotechnic heating element and attachment wires (UL® 1018 Wire Class 1) and provides a means to
attach a standard EMT conduit connector adapter to any combination ½” (12.7 mm) EMT; or ⅜” (9.5 mm) or ½”
(12.7mm) flexible conduit. The ETL® has a forty (40) pound maximum continuous tensile strength at standard
temperature which can only be achieved in installations where the link is subject to equal linear tension from
both ends. If side or “peel” forces are encountered (which is typical in most smoke damper installations) the
weight may have to be reduced, or the force vectors re-established. For this reason it is not permissible to bolt
or fix one end of the ETL® in most installations. Even if the Installation is gravity release (i.e. forty pounds
hanging straight down from the bottom link half) it is recommended to allow the link to “float” using “S” hooks,
straps or other attachments.


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