TM 9-1375-213-12
If M1 detonating cord clips are in short supply or not
available, a square knot (fig. 2-14) or one M1
detonating cord clip in lieu of the square knot may be
used provided at least 6-inch lengths extend from the
point of connection. When fabric-covered detonating
cord is used, fabric must not be removed. Knot may be
placed in water or in ground but cord must be detonated
from a dry end.
a. Branch Line Connections. A branch line is
fastened to a main line by means of a detonating cord
clip (fig. 213) or a girth hitch with one extra turn (fig.
of main line should be approximately 90 degrees. At
a smaller angle, branch line may be blown off main
line without being detonated. At least 6 inches of
the running end of branch line is left free beyond the
tie.
NOTE
The detonating cord does not always
generate a detonation wave in a backward
direction (i.e., through an angle over 90
degrees).
2-12. Detonating Cord Misfires
a Failure of Nonelectric Blasting Cap.
(1) If nonelectric blasting cap attached to
detonating cord fails to function, delay investigation for
at least 30 minutes.
(2) Fasten new blasting cap on detonating cord.
b. Failure of Electric Blasting Cap.
(1) If exposed electric blasting cap fastened to
detonating cord fails to fire, check connections to
machine.
(2) Try functioning machine again with maximum
b. Ring Main. A ring main is made by bringing the
possible effort.
main line back in the form of a loop and attaching it to
(3) If three or four tries do not produce results,
itself with a girth hitch with one extra turn (fig. 2-16) or
disconnect leads and test blasting circuit for any breaks
M1 detonating cord clip. This will detonate an almost
or short circuit.
unlimited number of charges. The ring main makes
(4) Short firing wire leads before leaving firing
detonation of all charges more positive because the
position to correct problem. If necessary, replace
detonating wave approaches branch lines from both
original blasting cap.
directions and charges will be detonated even when
c. Failure of Detonating Cord.
there is one break in the ring main. Branch line connec-
(1) If detonating cord fails to function at ex-
tions should be made perpendicular to the ring main.
plosion of an exposed electric or nonelectric blasting
Kinks in lines should be avoided, and changes in direc-
cap, investigate immediately.
tions should not be sharp. Any number of branch lines
(2) Attach new blasting cap to detonating cord,
may be connected to ring main, but a branch line is
taking care to fasten it properly.
never connected at a point where ring main is spliced. In
d. Failure of Branch Line. If detonating cord main
making detonating cord branch line connections, avoid
line detonates but a branch line fails, fasten blasting cap
crossing lines. However, if this is necessary, be sure to
to branch line and fire it separately.
have at least 1 foot of clearance at all points between
e. Failure of Charge to Explode.
detonating cords; otherwise cords will cut each other
(1) If charge is above ground, and detonating
and destroy firing system.
Change 8
