The muffle furnace is designed for uniform heating of substances to different temperatures. The muffle present in it, protects the heated object from direct exposure Gore products.

Navigation:

Distinguish muffle furnaces For several criteria.

• By source of heating.
• According to the processing mode.
• According to constructive data.

The source of heating the muffle furnace may be gas or electricity.

Processing mode happens:

• in the usual (air) atmosphere;
• in a special gas environment - hydrogen, argon, nitrogen and other gases;
• with vacuum pressure.

Structurally muffle furnaces are divided into furnaces:

• top loading;
• horizontal filling;
• cap - the furnace is separated from the submission;
• tubular furnaces.

In addition, there are several types of ovens for thermal indicators:

• furnaces with a small temperature: 100 - 500 degrees;
• furnaces S. middle temperatures: 400 - 900 degrees;
• furnaces with a large temperature: 400 - 1400 degrees;
• furnaces with very high temperatures: up to 1700 - 2000 degrees.

Note. From the temperature mode of the muffle furnace directly proportionally depends on its value, i.e., the higher the maximum temperature mark, the more expensive there will be a furnace.

The advantages of muffle furnaces refers to the protection of the heated substance from the products of combustion of fuel or evaporation of the heating elements and its uniform heating throughout the chamber.

In case of failure of the muffle, the design of the furnace allows you to promptly replace it, which greatly facilitates repair.

The disadvantage is a small heating rate (although it is not always necessary). In the muffle furnace it is impossible to produce high-speed heating modes. This is due to the fact that it is necessary to heat the muffle. What entails one more disadvantage - additional energy costs for heating.

The main component of the muffle furnace is a muffle that is most often made of ceramics. This material is universal for the manufacture of a furnace of different kind. There are still corundum muffins, but they are used only in a chemical environment.

Around the muffle is wound a heating element in the form of a wire and is embarrassed by ceramic coating.

Around the muffle is located heat insulation material And all this is trimmed with a metal casing of a metal sheet with a thickness of 1.5-2 mm.

Since the heating of the furnace begins around the muffle, then reach large temperatures (above 1150 degrees) is not possible. In this regard, the manufacturers have developed a special fibrous material for the manufacture of the muffle, which allows the heating elements from the inside. This makes it possible to increase the temperature limit of muffle furnaces. But the disadvantage of the fibrous material is its shortgue: under the action of gas evaporations, salts and oils from the heated material fiber collapses.

Today, Japanese very high-quality heating elements are used for high-temperature muffle furnaces that allow you to reach a temperature of temperatures up to 1750 degrees.

Furnaces working on gaseous fuel initially have higher temperature indicators.

For more uniform heating of the working chamber, some manufacturers embed ventilation. And for the output of combustion products, there is an exhaust mechanism that displays smoke and pairs from the furnace through the pipe.

To control and control the temperature in the furnace, an electronic thermostat is used, which is connected to the heater and the thermocouple. The thermostat allows you to control not only the temperature, but also the time of exposure of the product in the furnace. Moreover, these indicators have very high accuracy, especially in the laboratory muffle furnace, because the accuracy of the conducted research depends on their value and the result.

Application of muffle furnaces

The muffle furnace was widespread, first of all, as equipment for heat treatment of metals. But, thanks to its advantages, a muffle furnace (buy which can be in any region of Russia), much expanded its application area, and this is:

• heat treatment of metals (quenching, vacation, annealing, aging);
• ceramic materials firing - the final stage of processing ceramics;
• ozetzing - the transformation into the ascent of the studied substance without combustion to conduct a survey;
• cremation;
• the test analysis is a way of identifying and separating precious metals (gold, silver, platinum) from ore, alloys, finished products;
• drying - separation of moisture in the form of water or other liquid substance from materials;
• sterilization of tools in medicine (dentistry).

The heat treatment of metals can be produced in the home conditions, in laboratory or industrial scales. Based on this there is a whole the lineup muffle furnaces with different volumes of the working chamber, capacities and the maximum heating temperature. For personal use, you can buy a muffle oven for quenching knives, a laboratory muffle furnace is suitable for research.

For heat treatment of metals and alloys, a muffle furnace must have special characteristics.

First of all, the muffle furnace for hardening the metal, vacation and other things should have very good insulating characteristics. They are usually provided with several layers: refractory brick, fiber out ceramic material and protective casing from sheet metal. The bottom of the furnace should be equipped with special carbidrement plates and an additional pallet to protect against heating elements when loading and unloading. And most importantly, the electric muffle furnace must have special heating spirals From high quality alloy to ensure a sufficiently large heating temperature - up to 1,400 degrees.

Laboratory muffle furnace (price depends on power and constructive features) It can be used to heat the materials of different composition.

The muffle furnace for firing ceramics is used in artistic and pottery workshops. In addition to firing in it, heating of the wholesale, the melting of the glass is carried out. The muffle furnace for ceramics has a temperature regime to 1300 degrees and is equipped with an automatic regulator that allows you to slowly heat up and cool products without temperature jumps. Such a smooth transition is necessary and when clay firing is performed in a muffle furnace.

Buy a muffle furnace for ceramics can be directly from the manufacturer, which significantly reduces its cost.

Note. The muffle furnace for firing is often supplied with removable heating elements that can be easily replaced at failure.

The muffle furnace for firing ceramics (the price depends on the size, power, the loading and configuration method) may be the volume of the inner chamber from 1l to 200 liters and even more. The design of the furnace can be round with loading from above, chamber with loading ahead, have a cap oven. So the muffle furnace for firing ceramics, which can be used even for home use, Available for an extensive field of activity of any wizard.

To work with precious metals, a small muffle furnace is perfectly suitable in dentistry or even mini muffle furnace, the volume of the working chamber is about two liters.

Thinking about how much a muffle furnace is worth considering the required characteristics that should be present in it and choose good manufacturer. Russian-made muffle furnaces received good feedback Among consumers and have a good pricing policy.

Wide model range allows you to choose the muffle furnaces of the Russian Federation different design: horizontal and vertical muffle furnaces with the necessary location of the download, laboratory muffle furnaces (in Samara is the production base).

Known by their quality muffle oven. Such a muffle furnace (buy it in Moscow can immediately with delivery), got a lot positive feedback from leading enterprises of various directions.

Muffle furnace (buy in St. Petersburg different models) The company's electrical appliance also has proven itself among buyers.

A good quality is the Belarusian muffle furnace (it will not be a problem in Minsk, since there are many online stores that have such furnaces in the range).

Some masters are taken for making a muffle furnace with their own hands, as the factory muffle furnace (the price of which is still not small) they are not affordable. Making a furnace independently need to pay great attention to the fulfillment of the muffle. For domestic use, the muffle can be made of refractory clay, forming a working chamber around a cardboard frame. When clay dries, the cardboard is cleaned. Just before further assembly, it is necessary to burn the clay muffin so that it hardened and acquires the necessary hardness. Further assembly is no different from the factory.

But there are not so many such professionals such specialists, most of the consumers still prefer to buy a muffle stove, the price is chosen in its capabilities.

Quite often in the process various production It is required to produce heating, hardening or other thermal processing details. At the same time, it is necessary not only to observe a certain temperature mode, but also carry out cooling control. For these purposes, muffle furnaces are best suited.

They obtained their name thanks to a special device, which is a chamber made of heat-resistant materials designed to protect the part from various influences. For example, it prevents the contact of the product with protects against exposure ambient and contributes to maintaining the temperature regime.

There is a muffle furnace, which provides for a device of this type, where the muffle is installed stationary. It is quite practical and convenient, but after a certain period of operation, it is subject to complete re-equipment, or the camera is replaced. Therefore, in large industries, where such people are without stopping, it is used in a fundamentally different type of devices that have a replaceable package.

Such a muffle furnace works without a break, and the details are immersed in it already together with the muffle. Therefore, they require a certain amount. Given the short service life, such enterprises usually establish the production of muffles.

Cameras such furnaces from various properties are manufactured. If concrete technological process It requires fast cooling, then use thin-walled ceramics, when it is necessary to maintain heat in the oven for a long time after it is turned off, then a special or other package from heat-resistant and refractory material is used.

There are many methods of heating that the muffle furnace uses. It can work on gas, on firewood, on diesel or other liquid fuelBut most often use electric fan. They allow the heating of the furnace evenly (the cooling is also occurring), to carry out clear control over the temperature in the process of functioning. At the same time, special pyrometric devices can be connected to them, thanks to which all heating and cooling mode can be performed automatically. To control the temperature, thermocouples from special alloys are usually used, which are inside the instrument.

The simplest muffle furnace is made with a metal housing in which heating elements and controlling devices are installed. After that, its camera is manufactured, which is installed inside. At home, it is used for this and clay. They are the most affordable materials And have good specifications.

Such a muffle furnace can last long enough, and the replacement of the camera itself will not be much labor and will not entail special material costs. It is worth noting that most of the industrial devices of this type have exactly the same assembly principle, although for different conditions The muffle material can be changed.

The muffle furnace is a chamber device with a horizontal unloading system, which is an integral owner safety criterion when used. At certain cases, a mine option may be required in which the muffle is made deaf and is located vertically - this will not only significantly reduce the production time, but also will ensure heating objects without direct contact with air. In any case, the heating, camera and thermocouple controlling support remain key elements of the oven heating. necessary temperature.

History of origin

In the late XVII - early XVIII centuries. The French Karet Master Zheto began to invent the steering trapezium, which received his name, but it was not possible to start practical tests, because the axes of prototypes were constantly broken. Zhanto, who was confident that the invention would bring huge profits to him, completely desperate, because the carriage set on his axis was constantly tipped up right during the trip. However, the case was significantly advanced when a Russian nobleman appeared in the workshop to Janto, who wanted to order by the order of Peter the first luxury carriage from the best European master for a gift from Khan from Bukhara.

Having tried the product for durability, the nobleman advised Zhanto first to perform cementing in the muffle with the horns of coarse livestock elapsed into the powder, and only then begin to quench. Due to this method, inside the steel was to remain viscous, and the outside - to be covered with a solid woven crust, which will serve for many years before erased.

Despite the fact that the muffle furnace for firing ceramics was significantly modified over the past time, it continues to maintain its main characteristics. The muffle is a container resistant to high temperatures and having an impenetrable structure. In it, the item is undergoing the necessary heat treatment due to the fact that it completely isolates it from external influences, providing at the same time uniform heating from all sides.

Over time, the requirements for the quality of heat treatment have increased significantly, which has already allowed the mass application of furnaces on an industrial scale at the beginning of the XIX century. To date, even a low-temperature muffle furnace appeared, in which elements pass the hot curing procedure.

Application to date

• Safe overpass of valuable metals to avoid impurities in their structure and prevent direct interaction with the flame.
• Artificial aging of metals.
• Ceramics firing.
• Getting a smooth surface.
• Drying materials with a high degree of thermal conductivity.
• Burning objects to the state of mineral components, for example, when cremation of the body.

The muffle furnace is also used to grow single crystals and high-temperature processing medical equipment. Due to this, it is possible to destroy all malicious bacteria without damaging the tools themselves.

What is better to do or buy?

If you want to create such a device as a muffle furnace, do it yourself, be prepared for the fact that the volume of the muffle will not exceed the indicator in 7 liters, and the work itself will be long and time consuming. Before proceeding with the work, decide on the choice of a suitable model on which you can navigate. They differ:

• Heating temperature - from 100 to 2000 ° C.
• Design.
• Processing mode.
• Type of heating.

The undisputed sales leader is the muffle furnace model PM-8 and PM-10 - the muffle camera does not exceed 6.5 liters. It is her prototype that chooses most people for of own manufactureAfter all, the main material used in the work is only heat-resistant ceramics.

Available in several versions, to and m, differing only in the fact that the last digital control is present. The cost begins from 1 thousand dollars, while with hands you can buy a much cheapest option, the design of which will function as well as if you bought it in the store.

Despite the fact that this muffle furnace has excellent data, one essential drawback still has a door. It is significantly late in the process of work, because of which the owner often gets burns.

How to start creating?

For the first time, starting the manufacture of such a design as a muffle furnace, with their own hands, best to give preference to the design, which will be used for minor work. It is possible to significantly reduce the product by creating a slight hole in the rear wall of the muffle. It will be enough if you are not going to use such a design as a muffle furnace, on an industrial scale.

First, decide on what fuel - gas or electricity - a muffle furnace will work. The price for the device on gas will begin from 1 thousand dollars, however electrical system It is much easier to control. In addition, you will need to purchase a qualitative temperature sensor (thermocouple), which tracks the degree of heating to 1300 degrees. The fastening of the sensor to the furnace can be made of soft steel wire, carefully twisting it with passatsia so that the ends do not come into contact with each other.

For safety reasons, the muffle is better not to try to do it yourself, because with the wrong design, the product after processing simply will lose its cost. It is best to purchase ceramic chemical dishes in the laboratory equipment store under the required type of unloading.

Secondary purpose

The muffle furnace allows you to quickly remove moisture from the material. At the same time it does not matter, it will be ordinary water or liquid element chemical composition In the material. In addition, small designs are very convenient to use when checking (laboratory experiments), with ease of melting lead with gold or silver by oxidation by oxygen contained in the air of the structure for the isolation of precious metals in its pure form.

Getting started to choose a muffle furnace, it is better to give preference famous manufacturerswhich guarantee the quality of the goods providing high rates firing.

For the preferably about most people, muffle furnaces are completely useless. At the same time, the furnaces are necessary for those who whose profession or passion are related to the manufacture of jewelry, firing of ceramic products or metal smelting. Moreover, muffle furnaces are used in the creation of single crystals, checking, as well as in medicine - for high-temperature sterilization.

The cheapest factory models are about 30,000 rubles, which is noticeably hits the pocket of homemade craftsmen. But if you remember the school courses of physics, in particular, thermodynamics, it is quite possible to build such a design with your own hands.

According to the design features of the furnace can be:

• tubular;
• cylindrical shape;
• vertical location;
• horizontal location (simplest option).

Heat treatment can be carried out in air, vacuum or inert gas, but at home is only the first option.

Depending on the type of Tan, muffle devices are:

• gas;
• electric.

Operation of instruments on gas costs cheaper, but their independent manufacture prohibited by law. Electric is expensive, but have a significant advantage - the possibility of accurate temperature regime adjustment.

Important! A homemade muffle furnace can be given any shape and dimensions, perform it in the style that would come to general interior at home.

What will be required in work

The most convenient in operation is the vertical design. For its manufacture, it will be necessary:

• bulgarian, circles for metal;
• nippers;
• welding machine;
• nichrome wire, Ø1 mm;
• sheet steel 2,5 mm thick;
• basalt wool;
• corners;
• chammatory brick;
• silicone sealant;
• fire-resistant mix;
• respirator, plastic glasses.

Basic design elements

Important! The muffle furnace consumes a lot of electricity. For example, a device capable of hot to 1000 ° C is needed about 4 kW. Wiring, with which the furnace will connect to the network, must withstand heavy loads. Also need a machine with a stabilizer at 25 A.

Important! To do this, use asbestos, because when heated, it can be separated by carcinogens.

Manufacture of housing

Of steel sheet The rectangle is cut on the corresponding dimensions, bends into the radius, and the seam is brewed by means welding machine. The resulting cylinder is covered with fire-resistant paint and as soon as it dries, the bottom is welded to it (the circle cut from the same sheet). The bottom and walls are additionally strengthened by reinforcement. The volume of the cylinder should be calculated so that thermal insulation can be placed in it.

Important! When used, for example, oven, the bottom also need to strengthen the corners.

Furnace muffle with your own hands: Manufacturing instructions

The first stage. From the inside the cylinder is laid out basalt wool.

Stage second. Thermal insulation is constructed for which, as mentioned earlier, you need to take only chamotte brick. The procedure is as follows: in the housing it is necessary to docile seven bricks so that they formed the pipe. In the future she will serve working chamber.

Bricks are laid out in a row, while on each of them marks, for which they will clip. Next occurs directly trimming, after which the bricks should be such a form so that they can be connected to one hollow tube. In order to simplify the procedure, bricks can be numbered. At the end of the cutting, the pipe is going, it is tightened with a wire, the symmetry of the form is checked. If necessary, adjustment is carried out.

Important! Cutting need to be carried out on fresh air, preferably in a ventilated place, not forgetting about the means of individual protection (respirator, overalls, glasses).

Stage Third. The nichrome wire is twisted into the Ø6 mm spiral by winding the base (used electrode, pencil, etc.). Then the brick is removed from the housing and back stacked in a row.

Stage fourth. A spiral is applied to bricks and there are future grooves. The correctness of the lines is measured construction level. As a result, the stacked spiral should lead from the bottom to the top of the pipe. There is no contact of turns, since it can cause short circuit.

Stage fifth. To bring the ends of the spirals and their connection to the machine with the stabilizer between the pair of bricks, three strips are inserted, cut from ceramic tile, with done polypropylene and wire channels. These channels will be much simplified repair work in future.

Stage Sixth. Finished design It is placed in the steel case. At the same time, one brick is placed on the bottom of the housing, pre-coated with refractory glue. For the output of ceramic channels, holes in the appropriate places are made in the case.

Important! The spiral can be included only after drying the design, otherwise the wire is damaged.

Stage seventh. For the manufacture of the cover, the same sheet steel is used. Circle is cut on the size of the structure, for more reliable fixation on top of it mounted chammatory brick (1 pc.). Then the handles, a canopy and metal junk are welded. The edges of the covers in contact with the walls of the furnace are covered with a layer of fire-resistant silicone. Silicone is applied only for a preventive surface.

Stage seventh. Trial launch. For complete drying, it is installed in a warm, well-ventilated place. It is forbidden to use any heating devices, as this can lead to cracking of the masonry. After drying, the spirals are connected to the machine with the stabilizer, the heating power and the operating temperature is adjusted.

Important! To check the degree of drying of the masonry, you need to turn on the device at full power and see if it is evaporated with working surface Couple.

When operating the oven, the lid should be tightly closed.

Muffl furnace for ceramics

The image shows a primitive muffle furnace, which can be used to fir the small ceramic products.

For its manufacture, only a clay flower pot and electric tiles are required. Half put on the tile chamotte brick (so that the spiral does not come into contact with the ceramics), the product is put on it and closes the pot. A thyristor regulator is used to adjust the power.

Even in daylight it will be possible to notice that in a short time, after turning on the sides, the pot will get dark red light. From this point on, the countdown of the roasting is beginning, from five to twelve hours, depending on what is burned. If the transfer is observed, the power is slightly reduced.

Faiga Barrel oven

You can make a larger furnace from the faience barrel.

The first stage. First, at the bottom of the barrel of the diamond drill, a small hole is made for the release of expanding air.

Stage second. Next must be done under. To do this, the "foundation" of chamotte brick is collected on a small sheet and is connected by metal corners. Then in the upper part of the barrel, the grooves for the helix (no more than three or four) are done - the heating element of the required power will be laid in them.

Stage Third. It remains only to make an outer shell of galvanized steel. It is made removable, because it will be put on only after covering the product with a muffle (barrel). The space between the muffle and the outer shell is covered with asbestos.

The roasting procedure is no different from the previous version, but the temperature adjustment is carried out using thermocouples. The walls of the Barrel thick, as long as they appear (even without an outer shell), the ceramic product will be already thinned.

Safety technique

1. Working with a muffle furnace only persons familiar with the safety appliances during the operation of electrical appliances.
2. You can not start working without personal protective equipment - gloves, glasses, special clothes.
3. The design can be turned on only with grounding.
4. It is impossible to start work in the presence of chips, cracks and other design defects.
5. The furnace should always be under the supervision.
6. After switching on, you cannot touch the heating element (spiral).

Despite the numerous advantages, muffle furnaces, especially small sizes, are still very common among homemade craftsmen.

For a more detailed acquaintance with the design, see the above video.

Video - muffle furnace

The muffle furnace is a special thermal processing device. different materials. Her the main feature It is the presence of a special compartment called a muffle that protects the processed item from direct contact with fuel and combustion products. Such furnaces have wide spectrum Applications.

Purpose of muffle furnaces

Ceramics muffle furnaces are used at the final stage of production. They serve to quench the finished products, as well as to subject special paints into the surface of ceramic products. Technology processing is quite simple. The product prepared for processing is placed in a muffle made from special refractory materials. Next, the air inside the muffle is heated to the required temperature and is supported at such a level until the firing is completed. Thermal energy Served on the muffle with the heating elements. Muffle furnaces for ceramics often work from the electrical network, since they do not need to heat up to high temperaturesnecessary for metal processing. After the roasting procedure, any ceramic product acquires additional hardness and durability, and the tempered color drawing will hold on to several years, not erasering and not tight.

Laboratory muffle furnaces are used in jewelry, as well as in food, chemical and medical laboratories. Main a distinctive feature this type The furnaces is a high technical equipment, the possibility of operational replacement of the muffle and practically the ideal accuracy of installing operating parameters. Laboratory equipment is mainly intended for experiments to identify ways to improve the quality of a particular product. Therefore, the maximum accuracy of all indicators is a prerequisite. Laboratory furnaces quickly warm up to the desired temperature, equipped with a timer and ensure uniform heating airspace inside the muffle. Muffle cameras are subject to frequent replacement, as it is necessary to work with a variety of raw materials that requires the use of muffles from different materials.

Equipment device and operation

The muffle furnaces for metal processing are often working on fossil combustible raw materials. Their operating temperature is much higher than in electric muffle furnaces. Metal treatment implies their hardening, burning, normalization or melting. The processing process is quite expensive, so it is exposed only to products intended for work in aggressive environments, parts for high-precision engineering, jewelry, spare parts for medical prostheses. Processed metal much better resist negative impact Environment, has improved technical characteristics. And the most important thing is that in the process of processing it is not under the influence of gases allocated during fuel combustion.

The scheme of the muffle furnace looks quite simple. If desired, the simplified version of the device can be collected at home. The most important part of the design is the working chamber - the muffle. For its manufacture, it is necessary to take advantage of refractory clay or other heat-resistant material. First you need to collect the camera necessary form From cardboard or plywood. Then Outer layer The resulting design is covered with clay, and the wall thickness should be at least one centimeter. After clay hardens, it must be burned at a temperature of 900 degrees Celsius. For this procedure, a standard home furnace dried by coal is suitable.

After completion of the procedure and cooler of the workpiece, it is necessary to wind the resulting chamber of the faheral or nichrome wire, which will continue to serve heating element. From above, wire must be applied another layer of clay, without forgetting to leave the ends to connect to the electrical circuit. The roasting procedure is repeated again. The body of the future furnace is made of sheet steel with a thickness of 1.5-2 centimeters. In the finished package, a hole is done to output. Then the resulting muffles are placed inside the housing and connect contacts with the heating element. It is very gently and carefully carrying out work on the connection of the electrical circuit, since incorrect connection It may cause short circuit. If there is no experience in such affairs, it is better to seek help from specialists.

Empty space between the walls of the case and internal chamber You must fill asbestos asbestos. The calculation of the muffle furnace should be done in advance so that in the process of manufacture do not encounter the problem of lack of materials. Also, the device can be equipped with additional devices, such as a timer or electronic thermometer For convenience during operation. That's all, the resulting device can be subject to test tests and incorporate. For metal operations, it is, of course, is not suitable, but the firing ceramics will pull without problems.

How to choose a suitable oven?

Manufacturers of muffle furnaces permanently improve their products, as high competition in the market stimulates to the permanent satisfaction of client requests. In order not to lose its buyers and conquer new sales markets, it is necessary to keep up with the times. At the same time, the pricing policy should be adequate, otherwise the level of sales will be low regardless of product quality. ECPS muffle furnaces are completed with multi-stage adjustment systems and setup operating modes.

With their manufacture, only modern ecologically clean materials. The furnaces have a two-stage cycle of work, when at the first stage heating occurs, and on the second - stabilization of the resulting temperature. The control unit allows you to memorize the settings when you turn off the electricity. Competitive model - MIMP muffle furnace also has all the most listed advantages. Between these two manufacturers is the main struggle for the domestic market. And no opponent cannot achieve a decisive advantage. According to user reviews, products of both companies are located on summit, so they are leading suppliers in the industry.

Very often, users acquire a thermocouple for a muffle furnace. This device serves to measure the exact temperature. It is mainly necessary when the furnace itself is deprived of the built-in thermometer and does not show the current temperature value. For safe work Personnel is useful for a hood for a muffle furnace. This is a special element of technical furniture, inside which is placed working device. It is necessary for a person to accidentally do not dial about a device that heats up while driving.

The inner temperature of the muffle furnace can range from 400 to 2500 degrees Celsius, so even touch external surface May be very unpleasant. From the rest of the additional equipment, the muffles from different materials use in great demand. They are applied depending on working conditions with one or another material.

The price of a muffle furnace depends on its size, operating parameters and functional equipment. Self simple models Can be purchased for 20-25 thousand rubles. A device with high-tech control units, a large working chamber and a variety of work modes, over 1 million rubles will cost. As for the purchase of the device in the secondary market, here you can choose good model With a good functional for 100-120 thousand rubles. But it is worth understanding that buying goods from the hands, no one will give him a guarantee and, in the event of a breakdown, the repair will have to be carried out at its own expense.