What is delay in blasting?
The practice of initiating individual explosive decks, boreholes, or rows of boreholes at predetermined time intervals using delay detonators, as compared to instantaneous blasting where all holes are fired essentially simultaneously.
What is detonation cord made of?
Detonating cord (also called detonation cord, detacord, det. cord, detcord, primer cord or sun cord) is a thin, flexible plastic tube usually filled with pentaerythritol tetranitrate (PETN, pentrite).
What is delay detonators?
A delay electric detonator is a type of electric detonator that has a time lag in seconds before detonation.
What is trunk line delay?
Exel™ Trunkline Delay Detonators (TLDs) are non-electric millisecond delay detonators for surface initiation of signal tube or detonating cord downlines. Exel™ TLDs consist of a non-electric detonator, a length of Exel™ signal tube and a J-hook connector.
What is sequential blasting?
An alternative in electric blasting is the sequential blasting machine. Unlike the more conventional type capacitor discharge machines, the sequential machine delivers electronically timed bursts of energy to a number of conductors, or lead wires.
How does a detonation cord work?
Detonating cord, also called Cordeau and Primacord, is a hollow cord filled with an explosive material. It is fired by a detonator and is capable of initiating the detonation of certain other explosives at any number of points and in any desired pattern.
What is non incendive delay detonator?
Super Coal Delay Detonators are non-incendive in nature and have delay numbers zero to six (0 – 6) with a nominal time interval of 25 milliseconds between each successive delay number. The delay numbers are displayed on tags on the leg wire. Electrical Fuse Heads are fitted to the Copper filled shells.
How many grains are in det cord?
NONELECTRIC INITIATION WITH DETONATING CORD Detonating cord is sold in multiple sizes and loads. It is typically rated by the number of grains of explosive per linear foot (there are 7000 grains in a pound). Velocity of detonation is generally given as 21,000 feet per second.
What is the velocity of det cord?
The velocity is approximately 6,400 metres (21,000 feet) per second.
How long must personnel wait before approaching the detonation area?
With electric blasting caps or nonelectric detonation systems, wait at least 30 minutes.
When a misfire occurs during detonation operations How long must personnel wait?
If a misfire occurs while using cap and fuse, all personnel must remain at a safe distance from the charge for at least 1 hour. If other electric or nonelectric initiating methods are used, the blasting supervisor may reduce the waiting period to 30 minutes.
What is re factor of TNT?
The relative effectiveness factor (RE factor) relates an explosive’s demolition power to that of TNT, in units of the TNT equivalent/kg (TNTe/kg). The RE factor is the relative mass of TNT to which an explosive is equivalent: The greater the RE, the more powerful the explosive.
What is rock factor?
Rock factor. characterizes the rock properties and the uniformity index characterizes the drill and blast design. parameters. Prediction of blasted rock mass fragmentation is possible as the final result.
What is solid blasting?
Solid blasting in mining is a method used for blasting in coal faces. It consists of 12 to 15 shot holes, drilled in a pattern in the coal face equal to the gallery width. Certain explosives and millisecond delay detonators are used for solid blasting.
What are the advantage of solid blasting?
The advantages of solid blasting are: (1) It eliminates the use of coal cutting machines. This is particularly important in steep seams where flitting and control of coal cutting machine is difficult and risky.
What is powder factor in blasting?
The POWDER FACTOR is a relationship between how much rock is broken and how much explosive is used to break it. It can serve a variety of purposes, such as an indicator of how hard the rock is, or the cost of the explosives needed, or even as a guide to planning a shot.
What is detonation cord used for?
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. Detonation cord is used in commercial boilers to break up clinkers (solidified coal ash slag) adhering to tube structures.
What is a 50 grain detonating cord?
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,…
What is the velocity of detonation used for?
The velocity of detonation is sufficient to use it for synchronizing 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.
What is Cordtex used for in everyday life?
It is used to reliably and inexpensively chain together multiple explosive charges. Typical uses include mining, drilling, demolitions, and warfare. ” Cordtex ” and ” Primacord ” are two of many trademarks which have slipped into use as a generic term for this material.