TM 1-1500-204-23-11
(b) Hot or cold spots caused by uneven
loosely rolled when not in use. Rough
heating within the heat blanket can be
handling will lead to broken heating ele-
mitigated by placing a thin copper or
ments resulting in cold spots in the blan-
aluminum sheet under the heat blan-
ket.
ket. The sheet metal may conduct the
heat more evenly. Ensure the sheet
h. Heat Lamp. Infrared heat lamps can also be
metal matches the contour of the part
used for elevated temperature curing of composites if
being repaired to eliminate air pockets
a vacuum bag is not utilized. However, they are gen-
and ensure even distribution of pres-
erally not effective for producing curing temperatures
sure. Annealed metal is preferred.
above 150 F or for areas larger than 2 square feet.
It is also dificult to control the heat applied with a
(c) When using heat blankets in a haz-
lamp, and lamps tend to generate high-surface tem-
ardous environment such as class
peratures quickly. If controlled by thermostats, heat
1, division 1 or division 2, personnel
lamps can be useful in applying curing heat to large
shall, when available, use heat blankets
or irregular surfaces. Heat lamps are used to heat
designed for such areas. Heat blankets
components to assist in low of injection adhesives
designed for these areas often have a
as well as to reduce the gel time of paste adhesives
secondary safety device which ensures
and wet layup patches. See table 6-5 for average
the heat blanket does not reach the
temperatures when using one of two heat lamps at
auto-ignition temperature of aviation
varying distances from the surface. Heat lamps from
fuel.
different manufacturers produce different temperature
proiles. Each heat lamp coniguration must be evalu-
ated to determine their heating characteristics; this is
(d) Do not use heat blankets on compo-
usually done by conducting a thermal survey. Insulate
nents that have a radius smaller than
thermocouples with aluminum tape.
0.5 inch; too tight a radius will damage
the heat blanket.
(e) Handle heat blankets delicately; do not
fold, crush or pinch them. Store lat or
6-80
