Detonating cord

Detonating cord
Reinforced detonation cord filled with Pentaerythritol Tetranitrate (PETN)
United States Navy explosive ordnance disposal technicians double stranding detonation cord

Detonating cord (also called detonation cord, detacord, det. cord, detcord, primer cord or sun cord) is a thin, flexible plastic tube filled with PETN (Pentaerythritol tetranitrate). With the PETN exploding at a rate of approximately 4 miles per second, any common length of det cord appears to explode instantaneously. It is a high-speed fuse which explodes, rather than burns, and is suitable for detonating high explosives, usually pentaerythritol tetranitrate (PETN, Pentrite). The velocity of detonation is sufficient to use it for synchronising multiple charges to detonate almost simultaneously even if the charges are placed at different distances from the point of initiation. It is used to reliably and inexpensively chain together multiple explosive charges. Typical uses include mining, drilling, and demolitions.

"Cordtex" and "Primacord" are two of many trademarks which have slipped into use as a generic term for this material.

Contents

Effects

As a transmission medium, it can act as a downline between the initiator (usually a trigger) and the blast area, and as a trunkline connecting several different explosive charges. As a timing mechanism, detonation cord detonates at a very reliable rate (about 7,000–8,000 m/s), enabling engineers to control the pattern in which charges are detonated. This is particularly useful for demolitions, when structural elements need to be destroyed in a specific order to control the collapse of a building.

While it looks like nylon cord, the core is a compressed powdered explosive, usually PETN (Pentrite), and it is initiated by the use of a blasting cap. Detonation cord will initiate most commercial high explosives (dynamite, gelignite, sensitised gels, etc.) but will not initiate less sensitive blasting agents like ANFO on its own. 25 to 50 grain/foot (5.3 to 10.6 g/m) det cord has approximately the same initiation power as a blasting cap, but along its entire length. A small charge of PETN, TNT, or other explosive booster is required to bridge between the cord and a charge of insensitive blasting agent like ANFO or most water gels.

Rating

Detonating cord is rated in explosive mass per unit length. This is expressed in grains per foot in the United States, or in grams per metre elsewhere. A "grams per metre" rating will be roughly one fifth the "grains per foot" rating. For example, "50 grain det. cord" refers to detonating cord which has 50 grains of explosive per foot of length—or approximately 10 g/m. This is a typical "default" rating for connecting charges for blasting; lighter detonating cords may be used for "low noise blasting" and movie special effects, while heavier cords, used where the cord is employed to have some direct explosive effect—such as for precision rock carving work—may use 50 to 250 grain/foot (10 to 50 g/m) detonating cord.[1]

Direct employment

Low-yield detonating cord can be used as a precision cutting charge to remove cables, pipes, wiring, fiber optics, and other utility bundles by placing one or more complete wraps around the target. Detcord/Primacord is used in commercial boilers to break up clinkers (solidified coal ash slag) adhering to tube structures. Higher-yield detonating cord can be used to cut down small trees, although the process is very uneconomical compared to using bulk explosive, or even a chainsaw. High-yield detonating cord placed by divers has been used to remove old dock pilings and other underwater obstructions. Creating a slipknot from detonating cord yields a field improvised device that can be quickly employed to cut a locked doorknob off a door. Det cord can be taped in several rings, to the outline of a military man-sized target and detonated, breaching a man-sized hole into wooden doors or light interior walls. Detonating cord is also employed directly in building demolition where thin concrete slabs need be broken via channels drilled parallel to the surface, an advantage over dynamite since a lower minimum of explosive force may be used and smaller diameter holes are sufficient to contain the explosive.[2] Anything much more substantial than these uses requires the use of additional explosives.

Colloquialisms

The Finnish army colloquialism for detonation cord is anopin pyykkinaru (mother-in-law's clothesline), as it resembles ordinary clothesline.

In Filipino, the corresponding word mitsa has come to be used in a phrase “mitsa ng buhay” which translates to "detonating cord of [one’s] life", a metaphor for something that is very likely to cause one’s death via direct jeopardization (e.g. extreme sports, versus smoking).

References

  • Sapper School Demolitions Hand Book

External links


Wikimedia Foundation. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • detonating cord — sprogdinimo virvutė statusas T sritis Gynyba apibrėžtis Sprogstamųjų medžiagų pripildytas neperšlampamas, lankstus medžiaginis vamzdelis, kuriuo perduodama kibirkštis sprogdikliui. atitikmenys: angl. detonating cord pranc. cordeau détonant …   NATO terminų aiškinamasis žodynas

  • detonating cord amplifier — sprogdinimo virvutės stiprintuvas statusas T sritis Gynyba apibrėžtis Prie sprogdinimo virvutės prijungtas įtaisas, leidžiantis užsidegti užtaisui ir tuo pat metu perduodantis detonaciją kitam sprogmeniui. atitikmenys: angl. detonating cord… …   NATO terminų aiškinamasis žodynas

  • detonating cord — A waterproof, flexible fabric tube containing a high explosive designed to transmit the detonation wave …   Military dictionary

  • Plastic Igniter Cord — A plastic igniter cord (PIC) is a device for activating a number of safety fuse ends in a round of charges. In appearance it s like a thin rope and when ignited, an intense flame is transmitted along its length at a uniform rate. This flame will… …   Wikipedia

  • main detonating line — In demolition, a line of detonating cord used to transmit the detonation wave to two or more branches …   Military dictionary

  • explosive — explosively, adv. explosiveness, n. /ik sploh siv/, adj. 1. tending or serving to explode: an explosive temper; Nitroglycerin is an explosive substance. 2. pertaining to or of the nature of an explosion: explosive violence. 3. likely to lead to… …   Universalium

  • Ensign-Bickford Company — The Ensign Bickford Industries, Incorporated (formerly The Ensign Bickford Company) was started in 1836 in Simsbury, Connecticut as a manufacturer of William Bickford s safety fuse for use in mining. Safety fuse was a great advance in mining… …   Wikipedia

  • MRUD — The MRUD is a claymore (convex rectangle) shaped, plastic bodied, directional type Anti personnel mine designed to wound or kill by fragmentation. The casing is a light green colour with two detonator wells and three crude sight lines on the top… …   Wikipedia

  • Fuse (explosives) — In an explosive, pyrotechnic device or military munition, a fuse (or fuze) is the part of the device that initiates function. In common usage, the word fuse is used indiscriminately. However, when being specific (and in particular in a military… …   Wikipedia

  • Cordtex — is a type of detonating cord generally used in mining. It uses an explosive core of pentaerythritol tetranitrate which is inside its plastic coating. It is commonly the thickness of electrical extension cord and burns at 2 km per second. It is… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”