CHAPTER 5

EXPLOSIVES AND INInA TING DEVICES

5.0. TYPES OF EXPLOSIVES AND INITIAT-ING DEVICES THAT ARE USED BY THE NCF. .Reduced smoke and toxic fumes.

5.1. EXPLOSIVE TYPES. .Elimination of nitroglycerin effects.

5.1.1. M-1 Dynamite. The M-I military dynamiteis a Cyclotrimethylene Trinitramine (RDX) basedcomposite explosive containing no nitroglycerin. TheM-I military dynamite is packaged in 1/2 pound,paraffin-coated, cylindrical paper cartridges which havea nominal diameter of 1.25 inches and nominal lengthof 8 inches. It will not freeze in cold storage nor exudein hot storage. The composition does not absorb orretain moisture. Shipping containers do not requireturning during storage. It is safer to Store, handle, andtransport than 60 percent commercial dynamite. It isreliable underwater only up to 24 hours. Because of itslow sensitivity, sticks of military dynamite must be wellcompacted to ensure complete detonation of the entirecharge. There must not be any voids in loading ofboreholes in quarrying. Military dynamite willeventually detonate if set afire in a confined space.Thus, a secondary explosion can result from a boreholewith a void in its loading. After the first blast, it maytake up to 15 minutes for such an explosion to occur.

-Water resistance.

WG explosives are packaged in a heavy ruggedfihn in diameters from 1 1/2 to 4 inches, and lengths upto 16 inches. They are available in both cap sensitiveand non cap sensitive.

5.1.3. Ammonium Nitrate (ANFO). Free runningammonium nitrate field mixes are ideal for use in higWyjointed and dense material. The mixture ratio is criticalto the sensitivity of the explosive. A field mix of 94percent by weight of ammonium nitrate and 6 percentby weight of fuel oil (# 2 Diesel) or 50 pounds ofammonium nitrate unoiled prills and 3 quarts of fuel oilwill produce an insensitive explosive capable of fillingall the voids in the hole. It must be used in 3-inch orgreater diameter holes, confined and adequately primedto develop fun. strength. The use of blasting agents in3-inch or greater diameter holes is desirable in densematerial due to its low velocity. It is insensitive due tothe lack of nitroglycerin in its composition, andtherefore requires a high explosive primer.

5.1.4. Detonating Cord. Detonating cord is a coreof Pentaerythritol Tetranitrate (PETN) or RDX in atextile tube coated with a thin layer of asphalt. On topof this is an outer textile cover finished with a wax gumcomposition or plastic coating. It will transmit adetonating wave from one point to another at a ratebetween 20,000 and 24,000 feet per second. Apartially submerged water-soaked detonating cord willdetonate if initiated from a dry end. Although it doesnot lose its explosive properties by exposure to lowtemperatures, the covering becomes stiff and crackswhen bent. Great care is required in using detonatingcord primers in Arctic conditions. Detonating cord can

5.1.2. Water Gel. The tenn 'WG explosives I will

be used to describe water gel explosives. WGexplosives prove to be much safer than dynamite, theycontain no nitroglycerin, are sensitive to conventionalpriming methods, yet much more resistance thandynamite to accidental initiation from abusive impact,shock or fire. Some other advantages are:

.Greater control of borehole density. Theborehole density of WG explosives can be greatlyincreased by slitting or tamping the cartridge.

.Excellent fragmentation.

.Minimized danger of hole to hole propa-gation.

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will bum about 2 seconds per foot slower at an altitudeof 5000 feet than at sea level. Although a burning rateof approximately 120 seconds-per-yard as measuredunconfined at sea level is considered standard forcommercial safety fuse in the United States, fuses withdifferent burning rates are manufactured. Do notdepend on all fuse burning at 120 seconds-per-yard.Testing each roll prior to using in the area where thecharge is to be placed is required. Make sure to cutand discard a 6 inch length from the free end of the fuseto prevent a misfire caused by the exposed powderabsorbing moisture from the air. Then cut off aminimum 6 foot length of fuse to check the mostaccurate burning rate. Take particular precautions ifused underwater, as the rate of burning is increasedsignificantly. Test each roll underwater beforepreparing the charge. It is important to know that thefuse burns at the core and not with its cover. Howeverthe cover may bum without the ignition of the core.When properly ignited, the core ignites with a jet offlame called the "ignition spit." This is a jet of flamethat shoots out the end of the fuse the moment thepowder core is lighted. This spit shows the core islighted. PRACTICE UNTIL YOU KNOW THEIGNITION SPIT. Persons who do not recognize theignition spit or who are misled by the burning of thecover have been killed or injured by trying to relight thefuse which has been ignited.

CAUTION: Electric blasting caps of differentmanufactures should not be used in the same series.Their ignition systems may not be electricallycompatible and misfires may occur resulting in seriousmJury .

5.2.3. Nonelectric Blasting Caps. Nonelectricblasting caps, sometimes called fuse caps or ordinaryblasting caps, provide a nonelectric method of initiatingexplosive charges when properly used in conjunctionwith safety fuse. The safety fuse conveys a flame at arelatively uniform rate to the blasting cap where itignites the ignition charge. The Nonelectric blastingcap consists of an aluminum or copper shellapproximately 1 3/8 to 1 3/4 inches long, loaded withthree charges (fig 7):

.A base charge of High-velocity explosivein the bottom of the shell.

.A primer charge in the middle.

.A charge of ignition powder on the top,

The ignition powder insures flame pick-up from thesafety fuse, the primer charge converts the burning intodetonation and ignites the high explosive base charge.The NCF uses #6 and #8 Nonelectric blasting caps.

5.2.5. M60 Weatherproof Fuse Igniter. The M60device is designed to ignite a safety fuse in all sorts ofweather conditions, even underwater if properlywaterproofed. The fuse is inserted through a sealingrubber grommet and into a split collet which securesthe fuse when the end cap on the igniter is tightened. Apull on the pull ring releases the striker assembly,allowing the firing pin to drive against the primer,which ignites the fuse {fig 8).

CAUTION: Since the ignition powder is exposed inthe open end of the shell, Nonelectric blasting capsshould not be tampered with or abused in anyway.Such treatment can lead to premature detonationresulting in serious injury.

5.2.4. Safety Fuse. The safety fuse is used ingeneral demolitions. The safety fuse consists ofalmnonium nitrate black powder tightly wrapped withseveral layers of fiber and waterproofing material. Itmay be any color, but orange is the most common. Theburning rate may vary for the same or different rollsfrom 30 to 45 seconds per foot under differentatmospheric and climatic conditions. The burning rateshould not be less than 30 seconds per foot. A fusebums appreciably faster when it is confined by tampingor some other means of confinement; the greater theconfinement. the faster the burning rate. Conversely, afuse burns more slowly when it is subject to reducedexternal pressure. Other factors being equal, a fuse

5.2.6. MS-Connectors. MS connectors areNonelectric short interval, millisecond delay devices foruse on delaying blasts which are surface initiated by detcord. MS connectors are made of a molded plasticsleeve, that contains a copper tube delay element in thecenter portion. Each end of the sleeve is made so thedet cord can be looped and locked in the connector witha tapered pin. They are color coded for different time

intervals:

eMS-9 (9 milliseconds) blue.

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the rack bar down too hard, because only in thismanner will the machine develop its full energy. Priorto hooking up lead wires this machine should bewarmed up. This can be done by pushing the handledown as in nonnal use.

.to locate broken wires and connections in acircuit.

To measure resistance with this compactinstrument, place each of the two wires from the openend of the circuit on the two contact posts that extendout of the top of the galvanometer. The meter's topscale approximates the circuit's resistance (number ofohms), and the larger numbers on the bottom scale areonly reference points and do not relate to the actualnumber of ohms in the circuit.

5.3.3. No. 10 Twist Blasting Machine. Thismachine is designed to fire a maximum of 10, 30-footcopper wire, instantaneous electric blasting caps in aseries. Housed in a metal case, a special gasketprovides a watertight seal between the cover and thecase. This machine is used by blasters who never firemore than 10 caps in straight series. This machineshould also be warmed up by a few twists of the handleprior to hooking up lead wires.

Only special silver chloride batteries must beused to power the Blasting Galvanometer. Thegalvanometer has an adjustment screw on the back ofthe instrument that can be used to zero the needle whena conductor is placed across the two contact points.The silver chloride cell has become weak, and shouldbe replaced, when the instrument cannot be adjusted toa zero-ohm reading of the top scale and a 25-ohmreading on the bottom scale. The instrument will bechecked for proper operation prior to each use. Whenthe cell is exhausted, it must be replaced with the sametype of silver chloride cell. Never change batteries inthe vicinity of electric blasting caps. Never allow thesilver chloride cell, or any battery, to come in directcontact with electric blasting caps. DO NOTSUBSTITUTE ANY OrnER BAT1ERY FOR THESn.. VER cm..ORIDE.

5.3.4. DuPont 88-240. This machine ismanufactured by the ETI Corporation. The outsidecase construction is of heavy duty nonconductivepolyurethane with fully encap-sulated solid statecircuitry. It is a 330 volt, 17.4 joule unit with thecapability of firing 240 two ohm electric blasting capsin six series of 40 caps each connected in parallel to a3.0 ohm lead line. The power source is four 1.5 volt"C" alkaline batteries.

8Battery BA-245/6 0.9 volt FSN-6135-128-1632 for temperatures above 0 degrees F.

5.3.5. Rheostat. This instrument will test theefficiency of a generator-type blasting machine. It canalso be used to test capacitor discharge (CD) machines.The rheostat consists of a series of coils of varyingresistance, each labeled in ohms and in terms of anequivalent number of 30-foot copper wire electricblasting caps. To test the output of a generatormachine, a few electric blasting caps (and theequivalent resistance of several caps in the rheoStat) arewired in series and energized by blasting machinesbeing tested. Be certain the caps are positioned so thatinjury cannot occur from shrapnel or flying debris. Ifall the electric blasting caps fire, the machine's outputis sufficient to fire a series of electric blasting caps withthe same resistance.

8Battery BA-2245/6 0.9 volt FSN 6135-833-9909 for temperatures below 0 degrees F.

5.3.7. Blaster's Multimeter. The DuPont Blaster'sMultimeter, Model 101, is a compact volt-ohm-millivolt meter specifically designed to measureresistance, voltage, and current in electric blastingoperations. Blasters must use only the recommendedbatteries in these machines. Other batteries willproduce a hazardous current level. Never test anelectric blasting cap or blasting circuit directly with abattery, recommended or otherwise, and never allowany battery to come in direct contact with electricblasting caps. This versatile meter can be used to:

5.3.6. Blasting Galvanometer. The BlastingGalvanometer can measure the resistance in ohms ofthe blasting circuit:

-to determine if the bridge wires of individualelectric blasting caps are intact.

.Measure the resistances of a single blastingcircuit for continuity and the total resistance in a series-

-to detennine the continuity of an electricblasting cap series circuit.

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in-parallel circuit with a wgh degree of precision andaccuracy.

the crimped end of the blasting cap for use underwater.The rear portion of each jaw is shaped and sharpenedfor cutting fuses and detonating cords. One leg of thehandle is pointed to be used in punching cap wells inexplosive materials for easy insertion of blasting caps.The other leg has a screwdriver end. Cap crimpers aremade of a soft nonsparking metal, which will notconduct electricity. and must not be used as pliersbecause such use damages the crimping surface.Although there are numerous manufacturers ofcrimpers, the description described above is that of theDupont #4 crimper and most commonly found orreproduced. Blasters should visually check the type ofcrimper for proper operation.

.Survey blast sites to detennine if extraneouscurrent hazards exist.

.Measure a wide range of resistances necessaryto investigate static electricity hazards such as thosepossible in pnewnatic loading operations.

.Measure power line voltages up to 600 voltsAC and DC.

5.3.8. Cap Crimper. The cap crimper is used tosqueeze the shell of a Nonelectric blasting cap around asafety fuse securely enough to keep it from being pulledoff but not tightly enough to interfere with the burningof the powder train in the fuse. A stop on the handlelimits the closing of the jaws to prevent this. Thecrimper forms a water-resistant groove completelyaround the blasting cap. Apply a sealing compound to

5.3.9. Tamping Stick. A 1 inch diameter woodentamping stick slightly longer than the deepest hole aidsin loading. No metal parts are permitted in the stick,with the exception of a nonferrous metal coupling tojoin sections together. The stick must be inspectedcarefully before using to insure that no small rock chipsare clinging to the end that touches the explosive.

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