Fire method of blasting: technology, advantages, disadvantages, safety requirements

2024 Author: Henry Conors | [email protected]. Last modified: 2024-02-12 02:39

The ability of explosives (explosives) to engage in uncontrolled chemical reactions can lead to disastrous consequences. For example, a house explosion is predominantly the result of a gas leak. It can also be caused by careless handling of flammable and flammable substances. The TV can also become a source of explosion at home. On the street after a collision and a fire caused by a fuel leak, vehicles explode. However, this ability of explosives is used in mine-blasting business. There are specialists in pyrotechnics in the engineering troops, who, depending on the conditions and characteristics of the charges, undermine them in one way or another. Can use fire or electric.

According to experts, the fire method of blasting is considered the simplest. In addition, it can be produced without the use of complex and expensive devices. More about this method andblasting safety rules you will learn from this article.

Introducing the method

For the fire method of blasting, you need a bunch of sparks that are transmitted through a special cord. One of its ends is inserted into the sleeve, which is used as a detonator cap. Thus, with the help of a igniter cord, an impulse enters the sleeve, as a result of which its detonation follows, and then an explosive explosion. They use the fire method when they want to produce a serial detonation of several charges at different times. According to experts, it is more often used when detonating single charges.

About the advantages of the method

Unlike an electric method or a radio explosion, which requires special demolition machines, an electrical network and electric detonators, a fire one needs only a smoldering wick, matches, an incendiary tube with a detonator cap and a igniter cord. Tubes of industrial production are already equipped with a cord with a plastic sheath ZTP. Also, this element can be performed by a specialist from the engineering troops.

About shortcomings

Despite its undeniable advantages, the fire method of blasting is not without some drawbacks. First of all, a pyrotechnician performing demining is very risky. The fact is that when the cord ignites, it has to be near charges with explosives. The second disadvantage is that it is not technically possible for a military engineer or a civilian pyrotechnician (if mine clearance is carried out in the industrial sector) to check all the elements. But that's not all.

It may be that the incendiary tube or cord is of poor quality. In addition, it is impossible to neutralize a series of charges using fire blasting. They must be at a great distance from each other so that the explosion from one charge does not initiate others.

Types of capsules

The incendiary tube consists of a detonator cap, a igniter cord and an ignition (glow) wick. The primer initiates (excites detonation) an explosive charge.

KD 8-A and KD 8-M capsule models are used. These detonators have a similar design and dimensions: 4.7 cm long and 7 mm in diameter. They differ only in the type of explosive used for initiation and in the case material: they are made of aluminum and copper. The igniter cord is inserted into the detonator cap from the open side of the CD.

Description

The detonator cap is presented in the form of a sleeve with an inner diameter of 6.5 mm. One end of it is closed. On the other hand, a 1.02 gram high explosive is pressed in. The explosive must have increased power. Therefore, every military engineer uses RDX or Tetryl.

In the middle of the sleeve was equipped with a pressed inverted cup made of aluminum. Inside it contains BB. The lower layer on the side of the high-power high explosive is represented by lead azide (0.2 g), and teneres (0.1 g) is located on top. This element alonecannot initiate detonation, but only in tandem with lead azide. From the open end part of the sleeve is made hollow. The cup on this side is equipped with a small hole. To prevent explosives from waking up through it, a thin silk or nylon mesh is installed on the inside of the hole. From the closed end, the sleeve is equipped with a cumulative recess, in the direction of which the impulse force is much stronger.

How to properly handle the primer?

According to experts, the detonator cap is very sensitive to even minor external influences. It can be initiated not only by a spark, but also by impact, heat and friction. In addition, an explosion can occur if the cartridge case is flattened. Therefore, this element must be handled with the utmost care.

Keep the blasting cap away from drops and bumps. If mercury fulminate is used to load the cartridge case, the detonator must not be wetted. Capsules are stored and transported in special cardboard boxes of 50 pieces each. Also for this purpose, metal boxes are used that do not get moisture. In this case, the sleeves are kept in a vertical position by 100 pieces. Arrange them so that the muzzle is turned up.

Detonator caps are delivered to the place where blasting is carried out in special packages of 10 pieces or canisters made of wood. Carry them in bags, separate from explosives. If safety rules are followed, it is forbidden to carry shell casings in pockets during blasting.

About defective detonators

If there are through cracks on the sleeve or anydents, it is considered unusable. This also includes capsules with powdered composition for initiation walls. In addition, the detonators may have a solid coating or large spots. This indicates oxidation of the liner body. Such a primer is also considered defective.

About cord

Fireproof cord 10 meters long is rolled into a bay. This element consists of an outer shell and a powder core. The cord is labeled as OSHP, OSHDA or OSHA. It all depends on what type of winding is used. According to experts, 600 mm. OSHP brand cord burns out in 70 seconds. It can burn both in air and under water. It burns much faster (by 50%) at great depths. However, at a depth of 5 meters, the speed is difficult to predict. So that the powder core does not dampen when the cord is rolled into a bay, both ends are impregnated or sealed with wax. Today, engineering troops no longer supply such cords. The main scope of their application is the civilian industry. Unlike OSHP, OSHA and OSHDA have an asph alted shell, for the manufacture of which cotton or linen threads are used. The cords of these brands are grey-black.

This is due to the fact that the threads are impregnated with a special mastic - tar. OSHA is not used under water and in rooms with a high level of humidity. For such cases, OSHDA is provided with a double asph alt shell, and therefore high water-proofing properties. There is also a brand OShP-MG. The marking indicates that the igniter cord of the slowburning. Covered with a gray-blue plastic shell. The core is not represented by gunpowder, a multicomponent composition. Within 3 seconds, only 10 mm of length burns. To check how fast the cord will burn, you need to cut a piece 30 mm long from one end. and destroy. The next cut 60 mm piece is set on fire. Time is recorded using a stopwatch. If the cord suddenly died out or the burning rate is below 60 seconds, then you can not use it.

About the ignition wick

This item is needed to ignite the cord. For its manufacture, cotton or linen threads are used. They are woven into a cord, and then soaked in potassium nitrate. The wick is light yellow in color and 6 to 8 mm in diameter. Smoldering at a speed of 1 mm. in a minute. Before using the igniter wick, it is necessary to check its connection with the cord. The detonator cap and the igniter cord are connected by combined crimping. At the same time, they work with wire cutters for bare wires and cords, as well as screwdrivers.

About incendiary pipes

In the military and in the industrial sector, incendiary pipes (ST) of the following brands are used:

• ZTP-50. A product with a mechanical or grating igniter. Burns under water in 40 seconds and 50 in air. Complete with white cord.
• ZTP-150. Burn time increased to 100 seconds underwater (150 in air). A mechanical or grating igniter is also used.
• ZTP-300. The blue cord lights up for one minute (300 seconds under water).

Incendiary pipe in whichuses a mechanical igniter, consists of the following elements:

• Detonator cap.
• Sleeves.
• Aluminum sleeve. It has a number on it that indicates the deceleration time in seconds.
• Fireproof cord.
• Incendiary Node.
• Cases.
• Drummer.
• Springs with pin.
• Rings.

The case is such a TK with two slots: deep and shallow. In the first insert a check on the fuse. In this case, pulling it out by the ring is technically impossible. To do this, the igniter is screwed onto the tube assembly, the primer is screwed into the charge socket, and the pin is slightly lifted and transferred into a small slot. The product is held by the body in the left hand, the checks are pulled out with the right hand.

As a result, the spring begins to act on the drummer, which pierces the CD. This is followed by the ignition of the cord, the sparks of which initiate the explosion of the charge.

About the execution of the explosion by fire. Home

Upon arrival at the site, the engineer first of all prepares a segment of the OSH. The length of the cord will depend on the number of charges and the time it takes the pyrotechnician to hide in cover. If it is necessary to carry out a series of explosions, then the time to initiate all the TK is additionally measured. If the explosive charge is in the ground, then it will be more convenient to ignite the OSH with a length of at least 250 mm. Next, using a dry and sharp knife, cut the desired length of the cord at an angle of at least 45 degrees. This recommendation is duethe fact that the ignition of the powder core in the OSH occurs much faster if the cut is made at the most acute angle. The second end is cut at a right angle. Experts use a wooden lining. So that the cut does not turn out to be soaked and the gunpowder does not spill out of the core, the cut must be made with one strong pressure.

Second step

Next, you need to remove the detonator cap from the pencil case. It is carefully inspected before use. If any defects are found, she is sent to marriage. It may be that specks got into the capsule. To remove them, the barrel of the CD is lightly tapped on the nail. Items cannot be used for this purpose. Otherwise, the initiation of the explosive will occur. The end of the igniter cord, which is cut at a right angle, is carefully inserted into the sleeve until it stops. The OR should enter the CD easily. They must not be pressed or rotated, otherwise it will initiate an explosion of the capsule. If the pyrotechnician considers that the cord in the sleeve is too loose, then its end is wrapped with insulating tape or paper. Further, by crimping, the CD and the igniter cord are fixed. At the same time, the OSH is held in the left hand, holding the primer with the index finger.

Crimp is applied with the right hand. It is desirable that its lower part is flush with the cut of the CD or the cut of the primer protrudes by 0.2 cm. The ignition tube is crimped in two ways. After each compression, you can loosen the compression and rotate the TZ, or you can keep it motionless, working by crimping around its axis. This procedure is consideredperformed correctly if an even annular neck has formed on the CD. This indicates a strong connection between the igniter cord and the blasting cap.

In conclusion

It is forbidden to manufacture incendiary pipes near places where explosive materials are stored and issued. Cords, blasting caps and ignition tubes should not be placed on the ground even in dry weather. If it is raining or snowing, the ST is allowed to be made only with a raincoat or under a canopy. Often several explosives specialists have to work simultaneously. There must be a 5-meter distance between them.