Figure 1-17. M2 weatherproof fuse igniter.
Time Fuse. The time fuse is the second component of a nonelectric firing system. M700 time fuse burns at
about 40 seconds per foot, but each roll must be test-burned to determine its actual rate. Test-burning of time fuse
must be performed at least 25 feet downwind from blasting caps or other explosives. The procedures for test-
burning are as follows:
Since the powder in the time fuse is hygroscopic (meaning it will absorb water from the air), cut off and
discard the first six inches of the roll.
Cut off a three-foot section for test-burning, and attach a fuse igniter.
Ignite the fuse.
Record the starting and ending times of the burn. Compute the burning rate by dividing the time in seconds
by the length in feet. For example, if three feet of time fuse burned for 1 minute and 48 seconds, or 108
seconds, divide 108 seconds by 3 feet. The result is 36 seconds per foot.
Figure 1-18. Lighting time blasting fuse with a match.
MM0170
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