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[
GLOSSARY OF TERMS
]
–-–
Cavity Pillow (Insulation Bag): Same as accumulation
pillow, except used for thermal barrier.
Clamping Bars: See back-up bars.
Composite Belt: An expansion joint in which the
various plies are constructed of different materials that are
not integrally bonded together. Normally made up of an
inside liner, thermal insulating barrier and an outer cover.
Other special plies may be included.
Concurrent Movement: Combination of two or more
types (axial and lateral) of movements.
Corners: Molded, formed, or radial belt corners of
rectangular expansion joints.
Design Pressure: The maximum pressure, both positive
Accumulation Pillow: A pillow fabricated using
or negative that is expected during normal operation,
insulation material, wrapped in a woven fabric, then
not including periods of abnormal operation (see
placed in an expansion joint cavity. The purpose is to
excursion pressure).
either retard the intrusion of particulate, thermal
protection, or to resist pressure pulsation.
Design Temperature: The maximum or most severe
temperature expected during normal operation, not
Active Length (Live Length): The portion of the flexible
including periods of abnormal operation caused by
seal that is free to move. equipment failure. (See excursion temperature)
Back-Up Bars: Metal bars used for the purpose of Excursion Pressure: The maximum pressure, both
clamping the fabric expansion joint to mating ductwork positive and negative, the system could reach during
flanges. abnormal conditions or equipment failure.
Baffle (Liner): A metal shield that is designed to protect Excursion Temperature: The maximum temperature
the expansion joint from the abrasive particles in the gas the system could reach. Excursion temperature should be
stream and to reduce the flutter caused by air turbulence defined by maximum temperatures and time duration.
in the gas stream and in some cases may be part of the
overall thermal protection system. Face-To-Face: See breach opening.
Belt Type (Flat Belt): An expansion joint in which the Field Assembly: A joint that is assembled at the job
flexible fabric portion of the joint is flat and is bolted or site due to its size (too large to ship) or the location of
clamped to metal flanges or frame. |the breach opening makes it more practical to install
in sections. On-site assembly is required for certain
Bolt-In Flow Liner: A baffle that is designed to be bolted frame styles.
to the breach flange. This design can be either single or
telescoping and requires the use of a gasket seal. Field Splice: See splice
Typically used on integrally flanged expansion joints.
Flanges: That part of an expansion joint used for
Belt: The flexible element of a nonmetallic expansion fastening the joint into the system ductwork.
joint.
Flow Direction: Direction of gas movement through
Breach Opening: The distance between the mating duct the system.
flanges in which the joint is to be installed.
Flow Liner: See baffle
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