TM 9-1375-213-12
tions. Following the standard procedures of
keeping cap shunted until connected to the fir-
ing wire, which itself is kept shorted at the blast-
a. Cold Weather (+32F to -65F)
ing machine site, will not always offer sufficient
protection from accidental initiation. The saf-
WARNING
est practice is to suspend electric blasting opera-
tions under cold, dry blowing snow (or dust) con-
S T A T I C ELECTRICITY IS AN
d i t i o n s . If it is absolutely necessary to
WHEN
I N C R E A S E D HAZARD
undertake electric blasting operations under
OPERATING IN AN EXTREMELY
such conditions, a small amount of additional
COLD CLIMATE. CARE MUST BE
protection is obtained by keeping all wires on
TAKEN TO REDUCE THE
the ground at all times.
POSSIBILITY OF PREMATURE
(9) The side priming required of the sec-
ELECTRIC
D E T O N A T I O N OF
ond generation, new 40-pound cratering charge
BLASTING CAPS.
must be modified if the charge is cold (or wet).
The tape recommended to secure the required
In arctic operations, contamination with mois-
two booster charges to the sides of the charge
ture is the source of many difficulties. Moisture
can be the result of snow or ice getting into the
(PPP-T-60) loses adhesion at temperatures
below 40F. At cold temperatures, the following
material or box, condensation due to breathing
procedure is recommended for the basic side
of a partially filled container, or moisture con-
priming of the second generation, new 40-
densed from warm air in a partially filled con-
pound cratering charge and as an alternate for
tainer when it is brought outdoors from room
Generally, extreme cold will
other versions at cold temperatures.
temperatures.
crack insulation and cause electrical short cir-
NOTE
cuits. Extreme cold will also cause waterproof-
Since C-4 becomes stiff and hard to
ing materials to become hard, brittle, and easily
mold at low temperatures and likewise
damaged or broken. The following procedures
will be observed:
detonating cord becomes stiff and diffi-
cult to knot, wrapping each charge with
(1). Protect demolition materials from
detonating cord (at least 10 turns) may
snow or ice.
be done instead of molding the explo-
(2) Do not open sealed boxes or packages
sive around a Uli knot in the detonat-
until ready for use.
ing cord.
(3) Observe time delay versus tempera-
ture effects (table 2-5) for delay-type demolition
(a) Prime two M112, C-4 charges (or
firing device Ml.
(4) Below -20F block demolition charge
other one-pound + explosive charges) with deto-
nating cord in accordance with standard proce-
M3 (com C3) becomes brittle and cannot be
dures leaving enough free end of detonating
molded to fit target,
cords to extend to the common point of initia-
(5) Adhesive-backed block demolition
charges M112, M118, or M186 (roll) will not
tion (e.g. above ground if the charge is being
adhere to cold surfaces.
placed in a bore hole).
(b) Cut off approximately 20 feet of
(6) In cold weather, all blasting machines
twine (e.g. NSN 4020-00-241-8892 from the
should be exercised more than the usual four
Demolition Equipment Set).
strokes before use, to free the mechanism. A
drop of light machine oil should be applied to
(c) Securely tie one end of the twine
the plunger of the M32 or M34 before exercis-
to one of the primed booster charges.
ing the machine and whenever handle is slug-
(d) Place the above charge in position
gish. Even though the M32 and M34 will oper-
of the side of the cratering charge and tightly
wrap four revolutions of the twine around the
ate in extremely low temperatures, it is
advisable that they be carried in a pocket inside
cratering charge and the booster charge.
the operator's outer clothing in extremely cold
(e) Hold twine so that booster charge
weather to make it easier to use (see table 2-7).
stays put while positioning the second booster
charge on the opposite side of the cratering
(7) In extremely cold weather, either type
of blasting circuit test instrument must be car-
charge and then wrap several turns of the
ried in a pocket inside the operator's outer cloth-
twine around all three charges.
ing unless it is a galvanometers equipped with a
(f) Run the last six inches of twine
special, low temperature battery. If the tempera-
back through the existing loop or tie a knot to
ture is anywhere near the lower limit assigned
secure the booster charges to the cratering
to the galvanometers with the low temperature
charge.
battery this practice is advised for it, too (see
b. Hot Weather. Protect all demolition materi-
als from sources of extreme high temperature,
(8) Under arctic conditions, blowing
especially the direct rays of the sun. The tem-
snow generates static electricity and is thus an
perature limit for storage of most demolition
additional hazard to electric blasting opera-
materials is + 160F. The nominal limit for oper-
ation is + 140F.
2-48
