TM 31-210
Improvised Munitions Handbook
| Section VI |
No. 7 |
|
FUSE CORDS |
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| These fuse cords are used for igniting propellants and incendiaries or, with a non-electric blasting cap, to detonate explosives. | |
| FAST BURNING FUSE | |
| The burning rate of this fuse is approximately 40 in. (100 cm) per minute. | |
| MATERIALS REQUIRED: | |
| Soft Cotton String | |
|
Potassium nitrate (Saltpeter) 25 parts Fine Black Powder ---- or Charcoal 3 parts Sulphur 2 parts |
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| Piece of round stick | |
| Two pans or dishes | |
| PROCEDURE: | |
| 1. Moisten fine Black Powder to form a paste or
prepare a substitute as follows:
a. Dissolve Potassium Nitrate in an equal amount of water. b. Pulverize charcoal by spreading thinly on a hard surface and rolling the round stick over it ti crush to a fine powder. c. Pulverize sulphur in the same manner. d. Dry mix sulphur and charcoal. e. Add Potassium Nitrate solution to the dry mix to obtain a thoroughly wet paste. |
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2. Twist or braid three strands of cotton string together. |
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| 3. Rub paste mixture into twisted string with fingers and allow to dry. |
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| 4. Check actual burning rate of fuse by measuring the time it takes for a know length to burn. this is used to determine the length needed for a desired delay time. If 5 in. (12 1/2 cm) burns for 6 seconds, 50 in. (125 cm) of fuse cord will be needed to obtain a one minute (60 second) delay time. | |
| SLOW BURNING FUSE | |
| The burning rate of this fuse is approximately 2 in. (5 cm) per minute. | |
| MATERIAL REQUIRED | |
| Cotton String or 3 shoelaces | |
| Potassium Nitrate or Potassium Chlorate | |
| Granulated Sugar | |
| PROCEDURE | |
| 1. Wash cotton string or shoelaces in hot soapy water; rinse in fresh water. | |
| 2. Dissolve 1 part Potassium Nitrate or Potassium Chlorate and 1 part granulates sugar in 2 parts hot water. | |
| 3. Soak string or shoelaces in solution. | |
| 4. Twist or braid three strands of string together and allow to dry. | |
| 5. Check actual burning rate of fuse by measuring the time it takes for a know length to burn. this is used to determine the length needed for a desired delay time. If 5 in. (12 1/2 cm) burns for 1 minute, 50 in. (125 cm) of fuse cord will be needed to obtain a 5 minute delay. | |
| NOTE: The last few inches of this cord (the end inserted in the material to be ignited) should be coated with the fast burning Black Powder paste if possible. This must be done when the fuse is used to ignite a blasting cap. | |
| REMEMBER: The burning rate of either of these fuses can vary greatly. Do Not Use for ignition until you have checked their burning rate. |
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