Electric spark. Types of discharges The temperature of the electrical spark

In the conditions of production, the sources of ignition can be very diverse as by the nature of their appearance and in their parameters.
Among possible sources of ignition, we highlight outdoor fire and hot burning products; thermal manifestation of mechanical energy; thermal, manifestation of electrical energy; Thermal manifestation of chemical reactions.

Outdoor fire and hot burning products. Fires and explosions often arise from permanent or suddenly appearing sources of open fire and products accompanying the combustion process, sparks, hot gases.
Open fire can ignite almost all combustible substances, since the temperature in flame burning is very high (from 700 to 1500 ° C); At the same time stands out a large number of Heat and combustion process is usually long. Fire sources can be diverse - technological heating furnaces, fire-action reactors, regenerators with organic substances from non-combustible catalysts, furnaces and installations for burning and disposal of waste, flare devices for burning side and passing gases, smoking, use of torches for pipe heating and T . D. The basic measurement of fire protection against stationary sources of open fire is their isolation from combustible vapors and gases during accidents and damage. Therefore, fire-action devices are better placed on open areas with a specific fire gap from adjacent devices or isolate them, placing apart in closed rooms.
Outdoor tubular fire furnaces are equipped with a device that allows you to create a steam veil with a steam veil around them, and in the presence of adjacent devices with liquefied gases (for example, gas phrase installations) The furnaces are separated from them a deaf wall with a height of 2-3 m and its perforated pipe is paved from above to create a steam curtain. Electrocalkers or special gas stins are used for safe ignition ovens. Very often, fires and explosions arise in the production of fire (for example, welding) repair work due to unpreparedness of the devices (as stated above) and sites where they are located. Fire repair work, Besides
the presence of an open flame is accompanied by scattering
sides and fall on the underlying platforms of the metal parties, where they can ignore combustible materials. Therefore, in addition to the relevant training of devices to be repaired, the surrounding area is prepared. Within a radius of 10 m, all combustible materials and dust are removed, combined designs protect the screens, take measures to prevent sparks to the underlying floors. The overwhelming majority of fireworks are carried out using specially equipped stationary sites or workshops.
For the production of fireworks in each case, a special permission is obtained by the administration and the sanction of fire protection.

In the necessary cases, additional security measures are developing. Places of production of fireworks inspect specialists of the fire protection before the start and after the end of work. If necessary, at the time of the work of work, a fire post with an appropriate fire technique is established.
For smoking on the territory of the enterprise and in the workshops, special premises equip or identify the corresponding sites; For heating frozen pipes use hot water, water vapor or induction heating.
Sparks - hot solid particles, not completely burned fuel. The temperature of such sparks is most often in the range of 700-900 ° C. When in the air, the spark is combined relatively slowly, since carbon dioxide and other combustion products are partially adsorbed on its surface.
A decrease in fire hazard from the action of the spark is achieved by eliminating the reasons for sparking, and if necessary, the collapse of the sparks.
Calming and harvesting of the sparks when the furnaces and internal combustion engines are achieved by using sparking and sparking. The design of sparkling agents are very diverse. Devices for capturing and quenching sparks are based on the use of gravity (precipitating chambers), inertia forces (chambers with partitions, nozzles, grids, lanes), centrifugal force (cyclone

slippers, turbine-vortex), electric attraction forces (electrostatic filters), cooling products of combustion water (water curtains, catching the surface of the water), cooling and dilution of gases with water vapors, etc. In some cases set

/ - firebox; 2 - sedimizing chamber; 3 - cyclone sparkling; 4 - Loading nozzle
sequentially several sparking systems, as shown in Fig. 3.7.
Thermal manifestation of mechanical energy. Dangerous fire transformation of mechanical energy in warmth takes place when solid blows with the formation of sparks, friction of bodies with mutual movement relative to each other, adiabatic compression of gases, etc.
Sparks of impact and friction are formed with a sufficiently strong impact or intensive abrasion of metals and other solids. The high temperature of the spark of friction is determined not only by the quality of the metal, but also by the oxidation of its air oxygen. The temperature of the sparks of the unfounded small carbon steels exceeds sometimes

1500 ° C. Changes in the temperature of the sparks of the blow and friction depending on the material of the compounds of the bodies and the accompanying effort is shown on the graph of Fig. 3.8. Despite the high temperature, sparks of impact and friction have a small heat supply due to the insignificance of their mass. Numerous experiments found that

Fig. 3.8. The dependence of the temperature of the sparks of impact and friction on the pressure of the constructable bodies

acetylene, ethylene, dry carbon, carbon monoxide, hydrogen are most sensitive to sparks and friction. Substances having large period Inductions and requiring to ignite a significant amount of heat (methane, natural gas, ammonia, aerosols, etc.), the sparks of impact and friction are not ignited.
Sparks that have fallen on straightening dust and fibrous materials create foci of the tension that can cause a fire or explosion. The sparks obtained by blowing aluminum items in the oxidized surface of steel parts have a large constant ability. The prevention of explosions and fires from the sparks of impact and friction is achieved by using insincetent tools for everyday use and in emergency work in explosive workshops; mag-
thread separators and stone-tellers on the lines "feeding raw materials in machines of shock action, mills, etc. apparatus; the performance of machines that can comply with each other, from intrinsically safe metals or by strict adjustment of the size of the gap between them.
Incrementals are considered tools made of phosphorous bronze, copper, aluminum alloys AKM-5-2 and D-16, alloyed steel, containing 6-8% silicon and 2-5% of titanium, etc. HE is recommended to apply a stepped tool. In all cases, where possible, shock operation operations should be replaced with unstressed *. When using steel impact tools in explosive environments, the location of the work is stiguously ventilated, the constructive surfaces of the tool are lubricated with consistent lubricants.
Heated bodies from friction during mutual displacement depends on the state of the surfaces of the rubbing bodies, the quality of their lubricant, the pressure of the bodies on each other and the heat removal conditions in environment.
During the normal state and the proper operation of rubbing steam, the excess of the released heat is allocated in a timely manner into the environment, providing maintenance of temperature at a given level, i.e., if Qtp \u003d QNOT, then / slave \u003d const. The violation of this equality will lead to an increase in the temperature of the rubbing tel. For this reason, hazardous overheating takes place in the bearings of machines and apparatuses, when the conveyor belts and driving belts are bounce, when winding fibrous materials on rotating shafts, mechanical processing solid combustible substances, etc.
To reduce the possibility of overheating, instead of sliding bearings for high-speed and highly loaded shafts, rolling bearings are used.
Great importance It has a systematic lubrication of bearings (especially gliding bearings). For normal bearing lubrication, the grade of oil, which is accepted, taking into account the load and the number of revolutions of the shaft. If natural cooling is not enough to remove excess heat, organize the forced cooling of the bearing with running water or circulating oil, ensure control over the temperature

fattime bearings and fluid used for cooling them. Behind the state of bearings are systematically observed, purified from dust and dirt, no overload, vibrations, distortions and heating over the set temperatures are not allowed.
HE should be allowed "overloading conveyors, pinching tapes, loosening belt tension, tapes. Apply devices automatically signaling overload operation. Instead of flat gears, use clinorem, which practically exclude bounces.
From the fibers to the gaps between the rotating and fixed parts of the machine, gradually sealing the fibrous mass and its friction on the wall of the machine (in textiles, flax and pento-jewery factories, in the drying shops of chemical fiber plants, etc.) reduce the gaps between Treaspies and bearings, use bushings, housings, shields and other anti-winding devices to protect the shafts from contact with fibrous materials. In some cases, placing anti-winding knives, etc.
Heat the combustible gases and air when they are compressed in compressors. Increased gas temperature at adiabatic compression is determined by the equation

where TLL1 TK is the gas temperature before and after compression, ° K; PM PK is the initial and final pressure, kg / cm2 \\ k - an indicator of adiabat, for air? \u003d 1.41.
The gas temperature in the compressor cylinders at a normal compression ratio does not exceed 140-160 ° C. Since the final gas temperature in compression depends on the degree of compression, as well as from the value of the initial gas temperature, then in order to avoid excessive overheating during compression to high pressures, gas is compressed gradually In multistage compressors and cooled after each compression stage in the intexperse refrigerators. To avoid damage to the compressor, control the temperature and pressure of the gas.
Increased temperature in compression of air often leads to blades of compressors. Explosive concentrations are formed as a result of evaporation and decomposition of lubricating oil in conditions of elevated temperatures. Sources of ignition are foci of self-burning oil decomposition products, deprived in the discharge air duct and receiver. It has been established that for each IO0C temperature increase in the compressor cylinders, the oxidation processes are accelerated by 2-3 times. Naturally, the explosions, as a rule, occur not in the compressor cylinders, but in injection ducts and are accompanied by the combustion of oil condensate and oil decomposition products accumulated on internal surface Air ducts. To avoid explosions air compressorsIn addition to controlling the temperature and air pressure, the optimal lubricating oil feeds are established and strictly maintained, the injection ducts and receivers from combustible deposits are systematically cleaned.
Thermal manifestation of electrical energy. The thermal effect of the electric current can manifest itself in the form of electric sparks and arcs with a short circuit; excessive overheating of engines, machinery, contacts and individual sections of electrical networks during overloads and transition resistances; overheating as a result of the manifestation of vortex induction and self-induction currents; With spark discharges of static electricity and atmospheric electricity discharges.
When evaluating the possibility of fires from electrical equipment, it is necessary to take into account the presence, condition and compliance of the existing protection against environmental impact, short circuits, overloads, transition resistances, static and atmospheric discharges.
Thermal manifestation of chemical reactions. Chemical reactions occurring with the release of a significant amount of heat makes the potential possibility of fire, explosion, as it is possible to warm up the reacting or a number of combustible substances to the temperature of their self-ignition.
Chemicals for the danger of thermal manifestations of exothermic reactions are divided into the following groups (more on this is said in ch. I).
but. Substances flammable in contact with air, i.e. having a self-ignition temperature below ambient temperature (for example, aluminumorganic compounds) or heated above the temperature of their self-ignition.
b. Substances, self-turning in air, vegetable oils and animal fats, stone and charcoal, sulfur compounds of iron, soot, powdered aluminum, zinc, titanium, magnesium, peat, nitroglyphthalic lacquer waste, etc.
Self-burning substances are preventing a decrease in the oxidation surface, improving the heat removal conditions into the environment, a decrease in the initial temperature of the medium, the use of inhibitors of self-burning processes, insulation of substances from contact with air (storage and processing under the protection of non-combustible gases, .).
in. Substances flammable when interacting with water - alkali metals (Na, K, Li), calcium carbide, forged lime, powder and magnesium chips, titanium, aluminumorganic compounds (triethyl aluminum, triisobutyl aluminum, diethyl aluminum chloride, etc.). Many of this group of substances, when interacting with water, form combustible gases (hydrogen, acetylene), which in the reaction process can ignite, and some of them (for example, aluminumorganic compounds) during contact with water give an explosion. Naturally, such substances are stored and used, protecting against contact with them industrial, atmospheric and soil water.
g. Substances flammable in contact with each other are basically oxidizing agents capable of igniting combustible substances under certain conditions. The reactions of the interaction of oxidizing agents with combustible substances contribute to the chopping of substances, elevated temperature and the presence of process initiators. In some cases, the reaction is the nature of the explosion. Oxidants cannot be stored in conjunction with combustible substances, it is impossible to allow any interconnection between them if this is not due to the nature of the technological process.

d. Substances that are able to decompose with ignition or explosion when heating, impact, compression, etc.. These include explosives, nitrates, peroxide, hydropercycins, acetylene, porofor chkhs-57 (azodinitrileis-oil acid), etc. Such substances in the process of storage and use are protected from hazardous temperatures and hazardous mechanical effects.
Chemicals listed above groups can not be stored together, as well as with other combustible substances and materials.

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Blows of solid bodies with the formation of sparks.

With a certain strength of some solid bodies, sparks that call the sparks of the blow or friction can be formed about each other.

Sparks are heated to high temperatures (hot) particles of metal or stone (depending on which solid bodies are involved in collision) with a size of 0.1 to 0.5 mm and more.

The spark temperature of the strike from ordinary structural steels reaches the melting point of metal - 1550 ° C.

Despite the high temperature of the sparks, its flammable ability is relatively low, since due to small sizes (mass), the supply of thermal energy sparks is very small. Sparks are capable of ignite the vapor-high mixtures having a small induction period, a small minimum ignition energy. Acetylene, hydrogen, ethylene, carbon monoxide and serougerium are of the greatest danger in this regard.

The flammable ability of the spark, located at rest, above the flying, as the fixed spark is slower than cooled, it gives heat to the same volume of the combustible medium and, therefore, can heat it up to a higher temperature. Therefore, sparks that are alone are able to ignore even solids in crushed form (fiber, dust).

Sparks in the conditions of production are formed when working with an impact tool (wrench, hammers, chisels, etc.), when masting metal impurities and stones in machines with rotating mechanisms (devices with stirrers, fans, fans, etc.) , as well as with the blows of mobile mechanisms of the machine on fixed (hammer mills, fans, devices with folding lids, hatches, etc.).

Activities to prevent the dangerous manifestation of sparks from impact and friction:

Application in explosive areas (premises) to use an intrinsically safe tool.
Blowing clean air Places of production of repair and other works.
Exclusion from the machines of metal impurities and stones (magnetic cattles and stone chiefs).
To prevent the sparks from the blows of movable mechanisms of machines about fixed:
1. careful adjustment and shaft balancing;
2. verification of gaps between these mechanisms;
3. preventing machine overload.
Apply intrinsically safe fans for transporting steam and gas-air mixtures, dust and solid combustible materials.
In the premises of obtaining and storing acetylene, ethylene, etc. Floors to perform from an insincerible material or stipulated by their rubber mats.

Surface friction tel.

Moving relative to each other in contact with bodies requires energy costs for overcoming friction forces. This energy is almost entirely turning into warmth, which, in turn, depends on the type of friction, the properties of the rubbing surfaces (their nature, the degree of contamination, roughness), from pressure, surface size and initial temperature. Under normal conditions, the heat released in a timely manner is allocated, and the normal temperature mode is ensured. However, under certain conditions, the temperature of rubbing surfaces can increase to dangerous values \u200b\u200bunder which they can become a source of ignition.

Causes of growing temperature of rubbing bodies in general It is an increase in the amount of heat or a decrease in the heat sink. For these reasons in technological processes There are hazardous overheating of bearings, transport tapes and drive belts, fibrous combustible materials when winding them into rotating shafts, as well as solid combustible materials during their machining.

Activities for the prevention of dangerous manifestation of surface friction Tel:

Replacing the bearings of sliding on rolling bearings.
Control over lubrication, bearing temperature.
Control over the degree of tension of the conveyor belts, belts, not allowing the operation of machines with overload.
Replacing flat transfers to clinorem.
To prevent the winding of fibrous materials on rotating shafts, use:
1. the use of free-suiced sleeves, housings, etc. To protect the open sections of the shafts from contact with fibrous material;
2. overload prevention;
3. the device of special knives for cutting the winding fibrous materials;
4. installation of minimum gaps between the shaft and the bearing.
With mechanical processing of combustible materials, it is necessary:
1. comply with cutting mode
2. tool tool in a timely manner
3. use local cutting of cutting location (emulsion, oil, water, etc.).

Spark discharge

Spark discharge (electrical spark) - non-stationary form electric discharge , taking place in gas . This discharge usually occurs at the pressure of the order of atmospheric and is accompanied by a characteristic sound effect - "cod" sparks. The temperature in the main channel of the spark discharge can reach 10,000. In nature, spark discharges often occur as lightness . The distance, "punitive" spark in the air, depends on the voltage and is considered to be equal to 10 kv. 1 centimeter.

Conditions

Spark discharge usually happens if power Energy source is insufficient to maintain stationary arc discharge or glow discharge . In this case, simultaneously with a sharp increase in the discharge current, the voltage on the discharge gap for a very short time (from several microseconds up to several hundred microseconds) drops below the voltage of the spark discharge extension, which leads to discharge. Then the potential difference between the electrodes is growing again, reaches the ignition voltage and the process is repeated. In other cases, when the power of the energy source is large enough, the entire set of phenomena characteristic of this discharge is also observed, but they are only a transition process leading to the establishment of another type of discharge - most often arc . If the current source is not able to support an independent electrical discharge for a long time, then there is a form of an independent discharge, called a spark discharge.

Nature

Spark discharge is a bunch of bright, quickly disappearing or replacing each other's filamentous, often strongly branched stripes - spark channels. These channels are filled plasma which in the powerful spark discharge includes not only the ions of the source gas, but also the ions of the substance electrodes , intensively evaporated under the action of the discharge. The mechanism for the formation of spark channels (and, consequently, the occurrence of the spark discharge) is explained by the streamer theory of electrical breakdown of gases. According to this theory, from electronic avalanches arising in the electric field of the discharge gap, under certain conditions, streamers are formed - dimly glowing fine branched channels, which contain ionized gas atoms and free electrons cleaved from them. Among them can be allocated. The leader is a weakly glowing discharge, "Putting" path for the main discharge. It, moving from one electrode to another, overlaps the discharge gap and connects the electrodes with a continuous conductive channel. Then, in the opposite direction, the main discharge is held in the laughed path, accompanied by a sharp increase in current force and the amount of energy released in them. Each channel is expanding rapidly, as a result of which a shock wave occurs at its borders. A combination of shock waves from expanding spark channels generates the sound perceived as a "crackle" sparks (in case of lightning - thunder).

The ignition voltage of the spark discharge is usually large enough. Tension The electric field in sparking drops from several tens of kilovolts per centimeter (kV / cm) at the time of breakdown to ~ 100 volts per centimeter (V / cm) after several microseconds. The maximum current in a powerful spark discharge can reach the values \u200b\u200bof the order of several hundred thousand amps.

Special view of spark discharge - sliding spark discharge, arising along the surface of the gas and solid dielectric partition, placed between the electrodes, provided that the field strength of the punching strength of the air is exceeded. The area of \u200b\u200bthe sliding spark discharge, in which the charges of any single sign prevail, are induced on the surface of the dielectric charges of another sign, as a result of which spark channels are stealing on the surface of the dielectric, forming the so-called so-called figures of Lichtenberg . Processes close to what is happening during the spark discharge is also characterized by a wretched discharge, which is the transitional stage between crown And Iskraov.

The behavior of the spark discharge can be very good to see on slow motion shooting of discharges (FIMP. \u003d 500 Hz, U \u003d 400 kV) obtained from the Tesla transformer. The average current and pulse duration is insufficient for the ignition of the arc, but for the formation of a bright spark channel is quite suitable.

Notes

Sources

A. A. Vorobiev, high voltage technique. - Moscow-Leningrad, Gosnergoisdat, 1945.
Physical encyclopedia, T.2 - M.: Large Russian Encyclopedia p.218.
Raizer Yu. P. Gas discharge physics. - 2nd ed. - M.: Science, 1992. - 536 p. - ISBN 5-02014615-3.

Spark, one of the forms of electrical discharge in gases; It usually occurs at the pressure of the order of atmospheric and is accompanied by the characteristic sound effect of the "cod" sparks. In natural conditions I. r. Most often observed in the form of lightning ... ... Great Soviet Encyclopedia

The spark is electrical, non-stationary electric discharge in the gas occurring in the electric. Field with gas pressure to several. hundred kpa. It has a winding branching form and rapid development (approx. 10 7 (s), accompanied by a characteristic sound ... ... Big Encyclopedic Polytechnic Dictionary

- (electrical spark), non-stationary electric. The discharge in the gas occurring in the electric. Field with gas pressure to several. atm. Different with a winding branched form and rapid development (approx. 10 7c). Paced PA in ch. Channel I. r. reaches 10,000 to ... Natural science. encyclopedic Dictionary

Electric sparks are quite often caused by fires. They are able to ignite not only gases, liquids, dust, but also some solids. In the technique of electrical - sparks are often used as a source of ignition. The mechanism of ignition of combustible substances by electrical spark is more complicated than the ignition by the rolled body. When forming a spark in the gas volume between the electrodes, molecules and their ionization occur, which affects the nature of the flow of chemical reactions. Simultaneously with this, intensive temperature increases in the scissra. In this regard, two theories of the mechanism of ignition mechanism were put forward: ionic and thermal. Currently, this question is sufficiently not yet studied. Studies show that in the mechanism of ignition by electrical sparks, both electric and thermal factors are involved. At the same time, electric, in others - thermal are dominated in some conditions. Considering that the results of studies and conclusions from the point of view of ion theory do not contradict the thermal, with an explanation of the mechanism of ignition from electric sparks, usually leading to thermal theory.
Spark discharge. Electric spark arises if electric field The gas reaches a certain value of the EC (critical field strength or breakdown strength), which depends on the genus of the gas and its condition.
Reflection of the sound impulse of an electric spark from a flat wall. Photo obtained by a dark field. | Passing a sound pulse through a cylindrical wall with holes. Photo obtained by a dark field. Electric spark gives an extremely short flash; The speed of the Light is immeasurably more sound speed, the magnitude of which we will speak below.
Electric sparks that can appear with a short circuit of electrical wiring during electrical welding work, with the spark of electrical equipment, during static electricity discharges. The dimensions of the metal droplets reaches 5 mm during electrical welding and 3 mm with a short circuit of the wiring. The temperature of the metal droplets at electrical welding is close to the melting point, and the metal droplets produced with a short circuit of the wiring, above the melting point, for example, for aluminum, it reaches 2500 C. The temperature of the drop at the end of its flight from the source of the formation to the surface of the combustible substance is taken in the calculations of 800 FROM.
Electric spark is the most common thermal impact impulse. The spark occurs at the time of closure or opening the electrical circuit and has a temperature significantly exceeding the temperature of the ignition of many combustible substances.
The electric spark between the electrodes is obtained as a result of the pulsed discharges of the capacitor C generated by the electrical oscillating circuit. If there will be fluid (kerosene or oil) between the tool 1 and the detail 2, then the processing efficiency increases due to the fact that the metal particles are not sedired from the anode-part on the instrument.
The electric spark can be born without any conductors and networks.
Flame distribution characteristics in transitional mode with spark ignition (Olsen et al. / - hydrogen (successful ignition. 2 - propane (successful ignition. 3 - propane (ignition failure. Electric spark is two types, namely, high and low voltages. High voltage spark created by any generator high voltage, breaks through the spark gap of a pre-fixed size. The low-voltage spark is scattered at the point of rupture of the electrical circuit when self-induction occurs when interrupted current.
Electrical sparks are sources of small energy, but, as experience shows, it is often possible to become sources of ignition. Under normal working conditions, most electrical devices do not emissulate sparks, but the operation of certain devices is usually accompanied by sprouting.
The electric spark has the form of a brightly luminous thin channel connecting the electrodes: the channel is in a complex way bent and branched. Avalanche of electrons moves in the spark channel, causing a sharp increase in temperature and pressure, as well as a characteristic crackle. In the spark voltmeter brought ball electrodes and measure the distance at which there is a spark between the balls. Lightning is a gigantic electric spark.
Schematic scheme alternator activated arc AC. | Schematic diagram of the generator condensed spark.
Electric spark is a discharge created by a large potential difference between the electrodes. The substance of the electrode enters the spark analytical interval as a result of explosion-like emissions of the electrodes. Spark discharge with high current density and high temperature electrodes can go to high-voltage arc.
Spark discharge. Electric spark occurs if the electric field in the gas reaches a certain number of the EC's critical field strength or breakdown strength), which depends on the genus of the gas and its condition.
Electric spark decomposes NHS to composite elements. In contact with catalytically active substances, its partial decomposition occurs already with a relatively small heating. In the air ammonia under normal conditions, it does not burn; However, there are mixtures of ammonia with air, which in the ignition lights up. It burns as well, if you enter the gas flame burning in the air.
Electric spark decomposes the GSHD into composite elements. In contact with catalytically active substances, its partial decomposition occurs already with a relatively small heating. In the air ammonia under normal conditions, it does not burn; However, there are mixtures of ammonia with air, which in the ignition lights up. It burns as well, if you enter the gas flame burning in the air.
The electric spark allows you to successfully produce all sorts of operations - cutting the metals, make the holes of any shape and sizes in them, to grind, apply the coating, change the surface structure ... Especially profitable to process it from a very complex configuration from metal-ceramic solid alloys, carbide compositions, magnetic materials, High-strength heat-resistant steels and alloys and other hard-writable materials.
Electric spark arising between contacts when the chain break is quenched not only by accelerating the break; It also contributes to the gases allocated by Fiber, from which gaskets 6 are made specifically laid in one plane with movable contact.
Ignition system scheme. | | Battery system of ignition system. The electric spark is obtained as a result of the supply of high voltage current pulse to the electrodes of the candle. The interrupter ensures the opening of the contacts in accordance with the clock sequence, and the distributor 4 - the flow of high voltage pulses in accordance with the order of the cylinders.
Installation for ultrasonic cleaning Glass details with vacuuming of the working chamber. Electric spark removes a thin layer of glass from the surface being processed. When blowing through this arc, the inert gas (argon) is partially ionized and the molecules of pollution are destroyed under the action of ion bombardment.
Electric sparks in some cases can lead to explosions and fires. Therefore, it is recommended that parts of the installations or machines on which the accumulation of electrostatic electricity charges are accumulated, specifically connect the metal wire with the ground, thereby giving an electric charge free passage from the machine to the ground.
The electric spark consists of quickly disintegrating air atoms or another insulator and therefore presents a very short time an existing good conductor. The briefness of the spark discharge has long made it difficult to study, and only relatively recently managed to establish the most important laws that he obeys.
Spark discharge. Electric spark occurs if the electric field in the gas reaches some specific EC value (critical field strength, or breakdown strength), which depends on the genus of the gas and its state.

The usual electric spark, slipping in the generator's instrument, gave birth, as the scientist assumed, a spark in another instrument, isolated and remote from the first to several meters. So for the first time was detected predicted. Maxwell free electromagnetic field capable of transmitting signals without wires.
Soon the electric spark flames the alcohol, phosphorus and, finally, powder. The experience goes into the hands of the magicians, becomes a nail of circus programs, universally exciting burning interest in the mysterious agent - electricity.
Temperature flames of various gas mixtures. The high-voltage electric spark is an electric discharge in the air at normal pressure under the action of high voltage.
Electric sparks are also called the form of electric current through gas at a high-frequency discharge of the capacitor through a short discharge gap and a contour containing self-induction. In this case, during a significant proportion of the half-frequency current, the discharge is a arc discharge of an alternating mode.
Passing electric sparks through atmospheric air, Cavendish found that nitrogen is oxidized by air oxygen in nitrogen oxide, which can be translated into nitric acid. Following flax, solves thymryases, burning air nitrogen, you can get nitric acid salts that will easily replace the Chilean Selitra in the fields and increase the harvest: erynic crops.
Passing electric sparks through the atmospheric air, Cavendish found that nitrogen is oxidized by air oxygen in nitrogen oxide, which can be translated into nitric acid. Consequently, it solves thymryases, burning air nitrogen, you can get nitric acid salts that will easily replace the Chilean Selitra in the fields and increase the harvest: erynic crops.
High-frequency currents are excited from electric sparks. They spread along the wires and emit to the surrounding space. electromagnetic wavesinterfering with radio. These interference fall into the receiver in various ways: 1) through the receiver antenna, 2) through the wires of the lighting network, if the receiver network, 3) by induction from illuminating or any other wires on which interfering waves apply.
The effect of electrical spark on combustible mixtures is very difficult.
Obtaining an electrical spark in the required intensity during battery ignition is not limited to the minimum number of revolutions, and when igniting from magneto without an accelerative coupling, it is provided at about 100 rpm.
The ignition of electrical sparks compared to other methods requires minimal energy, since the small volume of gas on the path of the spark is heated to a high temperature for the maximum short time. The minimum energy of the sparks needed to ignite the explosive mixture at its optimal concentration is determined experimentally. It is given to normal atmospheric conditions - the pressure of 100 kPa and the temperature of 20 C. Usually the minimum energy required to ignite dusty explosive mixtures, one or two orders of magnitude higher than the energy required to ignite gas and steam-hazardous mixtures.
Ignition switch. When the test, the electric spark is evaporated with a thin layer of metal applied on paper, and near the place of breakdown paper is cleaned from the metal, and the breakdown hole is filled with oil, which restores the performance of the capacitor.
Electric sparks are most dangerous: almost always their actions and energy are sufficient to ignite combustible mixtures.

Finally, the electric spark is used to measure large potential differences using the ball splitting-K a, the electrodes of which serve two metal balls with a polished surface. The balls are spread, and they are fed to the measured to dissolve potentials. Then the balls are brought as long as the spark does not slip between them. Knowing the diameter of the balls, the distance between them, pressure, temperature and humidity of the air, find the difference in potentials between balls on special tables.
From the action of the electric spark decomposes with increasing volume. Methyl chloride - a strong reactive organic compound; Most of the reactions with methyl chloride consists in replacing halogen atoms on various radicals.
When electric sparks pass through liquid air, nitrogenous anhydride is formed as a blue powder.
To avoid electrical spark, you need separated parts of the gas pipeline to connect with a jumper and set the ground.
Changing the concentration limits of ignition from the power of the spark. An increase in the power of electric sparks leads to the expansion of the gas mixture area (explosion). However, there is a border here when a further change in ignition limits does not occur. Sparks of such power is called saturated. The use of them in devices to determine the concentration and temperature limits of ignition, the temperature of the outbreak and other values \u200b\u200bgives results that are not differing from ignition by rolled bodies and flames.
When the electrical spark is passed through a mixture of fluoride sulfur and hydrogen, H2S and HF are formed. S2F2 mixtures with sulfur gas form in the same conditions thionyl fluoride (SOF2), and mixtures with oxygen-mixture of thionyl fluoride and sulfur gas.
When the electric sparks pass through the air in a closed vessel above the water, there is a greater decrease in the volume of gas than when combing phosphorus in it.
The energy of the electrical spark is necessary to initiate an explosive decomposition of acetylene, strongly depends on the pressure, which is obvious when it decreases. According to S. M. Kogarko and Ivanov35, the explosive decomposition of acetylene is possible even at absolute pressure of 0 65 from if the spark energy is 1200 J. Under atmospheric pressure The energy of the initiating spark is 250 J.
In the absence of electrical spark or such light-sparing impurities, such as fat, reactions usually proceed noticeably only when high temperatures. Ethforane C2FE slowly reacts with a diluted fluorine at 300, while K-heptaran reacts rapidly when the mixture of the mixture is sparkling.
When electric sparks pass through oxygen or air, a characteristic smell appears, the cause of which is the formation of a new substance - ozone. Ozone can be obtained from perfectly pure oxygen; It follows that it consists only of oxygen and is its allotropic modification.
The energy of such an electrical spark can be sufficient to ignite a combustible or explosive mixture. A spark discharge at a voltage of 3000 V can cause the ignition of almost all pair and gas-air mixtures, and at 5,000 V is the ignition of most of the combustible dust and fibers. Thus, the electrostatic charges arising under production conditions can serve as an ignition source capable in the presence of combustible mixtures to cause a fire or explosion.
The energy of such an electrical spark can be quite large for the ignition of a combustible or explosive mixture.
When transmitting electric sparks through oxygen, ozone is formed - gas, which includes one element - oxygen; Ozone has a density of 1 5 times greater than oxygen.
When slipping the electrical spark in the air space between the two electrodes there is a shock wave. When exposed to this wave on the surface of the calibration unit or directly to PE, the elastic pulse is excited in the last of the order of several microseconds.

Electric spark. Types of discharges The temperature of the electrical spark

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see also

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