Description
Product introduction:
WRNK-101, WRNK-102, WRNK-108, WRNK-109, WRNK-201, WRNK-202, WRNK-208, WRNK-209, WRNK-301, WRNK-302, WRNK-308, WRNK-309, WRNK-401, WRNK-402, WRNK-408, WRNK-409, WRNK-501, WRNK-502, WRNK-508, WRNK-509, WRNK-121, WRNK-122, WRNK-128, WRNK-129, WRNK-221, WRNK-222, WRNK-228, WRNK-229, WRNK-321, WRNK-322, WRNK-328, WRNK-329, WRNK-421, WRNK-422, WRNK-428, WRNK-429, WRNK-521, WRNK-522, WRNK-528, WRNK-529, WRNK-131, WRNK-132, WRNK-138, WRNK-139, WRNK-231, WRNK-232, WRNK-238, WRNK-239, WRNK-331, WRNK-332, WRNK-338, WRNK-339, WRNK-431, WRNK-432, WRNK-438, WRNK-439, WRNK-531, WRNK-532, WRNK-538, WRNK-539, WRNK-181, WRNK-182, WRNK-188, WRNK-189, WRNK-281, WRNK-282, WRNK-288, WRNK-289, WRNK-381, WRNK-382, WRNK-388, WRNK-389, WRNK-481, WRNK-482, WRNK-488, WRNK-489, WRNK-581, WRNK-582, WRNK-588, WRNK-589, WRNK-191, WRNK-192, WRNK-198, WRNK-199, WRNK-291, WRNK-292, WRNK-298, WRNK-299, WRNK-391, WRNK-392, WRNK-398, WRNK-399, WRNK-491, WRNK-492, WRNK-498, WRNK-499, WRNK-591, WRNK-592, WRNK-598, WRNK-599, WRNK-130, WRNK-135, WRNK-136, WRNK-230, WRNK-235, WRNK-236 armored thermocouples are used as temperature measuring sensors. They are usually used together with temperature transmitters, regulators and display instruments to form a process control system for directly measuring or controlling fluids in the range of 0-1800 °C in various production processes. Temperatures such as steam and gaseous media as well as solid surfaces. The braided thermocouple has many advantages such as bending, high pressure resistance, fast thermal response time and durability. It is the same as the industrial assembled thermocouple. It is used as a temperature measuring sensor, usually matched with display instruments, recording instruments and electronic regulators. use.
Internationally applied thermocouples have a standard specification. Internationally, thermocouples are divided into eight different scales, namely B, R, S, K, N, E, J and T, which measure the lowest temperature. Below 270 degrees Celsius, up to 1800 degrees Celsius, where B, R, S belong to the platinum series of thermocouples, because platinum is a precious metal, they are also known as precious metal thermocouples and the remaining few are called cheap metal thermocouples . There are two types of thermocouples, normal and armored. Ordinary thermocouples are generally composed of hot electrodes, insulating tubes, protective sleeves and junction boxes, while armored thermocouples are assembled by combining thermocouple wires, insulating materials and metal protective sleeves. Stretched into a solid combination. However, the electrical signal of the thermocouple requires a special wire for transmission. This wire is called a compensation wire. Different thermocouples require different compensation wires, the main function of which is to connect with the thermocouple, so that the reference end of the thermocouple is far away from the power supply, so that the temperature of the reference junction is stable. The compensation wire is divided into two types: compensation type and extension type. The chemical composition of the extension wire is the same as that of the compensated thermocouple. However, in practice, the extension type wire is not made of the same material as the thermocouple, and is generally used and thermoelectric. Instead of wires with the same electron density. The connection of the compensation wire to the thermocouple is generally clear. The positive terminal of the thermocouple is connected to the red line of the compensation wire, and the negative electrode is connected to the remaining color. Most of the materials for the compensation wires are made of copper-nickel alloy.
Armored thermocouples, like industrial assembled thermocouples, are used as sensors for measuring temperature, usually in conjunction with display instruments, recording instruments, and electronic regulators. They can also be used as temperature sensing elements for fabricated thermocouples. It can directly measure the temperature of liquids, vapors and their gaseous media and solid surfaces from 0 °C to 800 °C in various production processes. Compared to fabricated thermocouples, armored thermocouples offer the advantages of flexibility, high pressure resistance, short thermal response time and ruggedness. [1]
Since the materials of armored thermocouples are generally more expensive (especially when precious metals are used), the distance between the temperature measurement points and the meter is very long. In order to save the armored thermocouple materials and reduce the cost, the compensation wires are usually used to heat the armor. The even cold end (free end) extends into a relatively stable temperature control room and is connected to the meter terminals. It must be pointed out that the function of the thermocouple compensation wire only extends the hot electrode, so that the cold end of the armored thermocouple moves to the instrument terminal of the control room, which does not eliminate the influence of the temperature change of the cold end on the temperature measurement, and cannot compensate. effect. Therefore, other correction methods are needed to compensate for the influence of the cold junction temperature t0 ≠ 0 ° C on the temperature measurement. When using the armored thermocouple compensation wire, the model must be matched, the polarity cannot be connected incorrectly, and the temperature of the connection between the compensation wire and the armored thermocouple must not exceed 100 °C.
Classification:
Open-end type: Short thermal response time; suitable for measuring engine exhaust, etc. Temperature measurement requiring fast response; low mechanical strength.
Shell type: short thermal response time; large nominal pressure (up to 34MPa); not suitable for applications with electromagnetic interference.
Insulation type: The thermal response time is longer than the first two, and the service life is long; anti-electromagnetic interference; this form is often used in cases where there is no special requirement for thermal response time.
Separate type: Double branch, avoid signal interference, its characteristics are the same as the insulation type.
Working principle:
A galvanic couple is welded together with two conductors of different compositions. When the temperature at both ends is different, a thermoelectric potential is generated in the loop. Therefore, the potential galvanic couple is a temperature sensing element that measures the temperature to measure the temperature. A converter that converts a temperature signal into an electrical signal and displays it by a display meter.
The basic principle of thermocouple measurement of temperature is the thermoelectric effect. The metal conductors of two different components are connected end to end in a closed loop. If the temperature of the two junctions is not equal, a thermoelectromotive force is generated in the loop to form a thermal current. Thermoelectric effect. Thermocouples are made by welding two different metal materials at one end. The welded end is called the measuring end, the unwelded end is called the reference end, and the reference end is usually constant at a certain temperature (such as 00C) when used. At the junction, a thermoelectric potential is generated. If the temperature of the reference terminal is constant, the magnitude and direction of the thermoelectric potential are only related to the characteristics of the two metal materials and the temperature of the measuring end, regardless of the fineness and length of the potential couple. When the temperature at the measuring end changes, the potential potential also changes, and there is a fixed function relationship between the temperature and the thermoelectric potential. With this relationship, the temperature can be measured.
The armored thermocouple electrode is a two-component conductor that is welded at both ends to form a loop. The direct temperature measuring end is called the working end, and the terminal end is called the cold end, also called the reference end. When there is a temperature difference between the working end and the reference end, a thermal current is generated in the circuit, and the display meter is connected, and the corresponding temperature value of the thermoelectromotive force generated by the thermocouple is indicated on the meter. The thermoelectromotive force of the armored thermocouple will increase with the temperature of the measuring end. The magnitude of the thermoelectromotive force is only related to the thermocouple conductor material and the temperature difference between the two ends, and has nothing to do with the length and diameter of the hot electrode. The structural principle of the armored thermocouple is that it is made of conductor, high-insulation magnesia, and jacket stainless steel protection tube. Armored thermocouple products are mainly composed of junction boxes, terminal blocks and armored thermocouples, and are equipped with various mounting fixtures.
Basic structure:
Armored thermocouples are mainly composed of junction boxes, terminal blocks and armored thermocouple elements, and are equipped with various mounting fixtures. The mounting type fixing device is used for user installation. Armored thermocouples are: five types of structure: no fixed device, fixed ferrule type, movable ferrule type, fixed flange type, movable flange type. The fixed ferrule type is only used for one-time fixed use, and the movable ferrule type can be used for multiple times.
Main feature:
Armored thermocouple is the most widely used temperature device in temperature measurement. Its main features are wide temperature range, stable performance, simple structure, good dynamic response, and better transmission of 4-20mA electrical signals for automatic control. And centralized control. In addition, the thermal response time is less, the dynamic error is reduced; the installation is flexible; the measurement range is large; the mechanical strength is high, and the withstand voltage performance is the advantage of the armored thermocouple.
Instructions:
The verification method of the metal melt quick armored thermocouple verification device is as follows:
The device is mainly composed of a flat heating coil capable of accommodating two quartz tubes to be tested, two armored thermocouples having the same shape as the measured coupler, and corresponding temperature-controlled display output devices. The verification method is to first use two calibration thermocouples to find the point in the flat heating coil that makes the two calibrated couples have the same thermoelectric potential, and replace one of the calibrated couples with the detected one, and wait for other conditions to remain unchanged. After the reading of the detected couple is stabilized, it is compared with the reading of the calibrated couple to know whether the magnitude of the detected couple is accurate. This method provides a laboratory test for rapid temperature measurement of thermocouples, allowing rapid temperature thermocouples to be tested at multiple temperature points and comprehensively evaluated.
The utility model is characterized in that: a. The device is composed of a flat heating coil, a pair of calibration armored thermocouples and a temperature control display output device. b. The verification method is to first insert two calibration thermocouples from opposite ends of the heating coil to make the hot end of the armored thermocouple contact, and change the thermocouple of the two calibration thermocouples by changing the position of the calibration thermocouple in the heating coil. Replace one of the calibrated thermocouples with the fast thermocouple to be tested, and compare the thermoelectric potential value in the steady state with the calibrated thermocouple thermoelectric potential to know the accuracy of the tested fast armored thermocouple.
Skills:
There are a lot of tricks to use armored thermocouples.
1. With bendability, the armored thermal resistor can be bent in any direction except the head, so it is suitable for the construction of complex, small device temperature.
2. Armored thermocouples have good vibration and impact resistance. Therefore, its life is longer than ordinary thermal resistance.
3. The armored thermocouple has a long service life. The resistor body of the Kay thermal resistor is not easily eroded by the harmful medium due to the twisted cover of the iron insulation material and the maintenance of the metal sleeve.
4. Explosion-proof type thermal resistance is limited to the explosion caused by sparks or arcs in the explosion-mixed gas inside the casing through a special-structure junction box in the junction box.
5. The production site will not cause an explosion. Explosion-proof thermal resistance can be used for temperature measurement in explosive areas where the Bla--B3c level is explosive. Anti-corrosion thermal resistance 5) Anti-corrosion thermal resistance is made of PTFE anti-corrosion material.
6. As a whole protective sleeve or two-section casing, it can also be used as anti-corrosion treatment of the material directly on the protection tube, which is divided into three types: spraying, sintering and casing sealing.
7. It is suitable for measurement in corrosive medium with strong alkali. It can withstand temperature of 250 °C. It can also be fixed thread with the same PTFE material for fixed installation.
8. Select the appropriate type, specification and maintenance tube data for the thermal resistance based on the measured temperature range and side volume.
Faults and solutions:
The ceramic pores of the armored thermocouple are disabled by the plugged components, and are often treated by the method of electrification and dust removal, but the effect is not ideal and can not be used in the flammable and explosive environment, which can reflect the measured more correctly and quickly. The actual temperature of the end face is suitable for measuring the end face temperature of the bearing bush and other parts. It is not only widely used in industrial temperature measurement, but also made into a standard reference instrument. It has a display instrument that is compatible with it.
Non-standardized thermocouples are inferior to standardized thermocouples in terms of application range or magnitude, and generally do not have a uniform indexing table, which is mainly used for measurement in some special occasions. The thermoelectromotive force is a single-valued function of the working temperature. The indexing table for the relationship between the thermocouple temperature and the thermoelectromotive force is made when the cold junction temperature is zero. For this reason, a special compensation wire is used to extend the cold end.
The main failure modes are: wire breakage caused by vibration and thermocouple breakage, and second, short circuit or disconnection of thermocouple due to bending.
Application:
Usually used with display instruments, recording instruments, electronic computers, etc. Direct measurement of liquid, vapor and gaseous media and solid surface temperatures in the range of 0-1300 degrees in various production processes.
Installation Precautions:
1. The height of the clamps must be the same, usually 150~200mm above the level;
2, briquetting welding requires three-sided spot welding, thermocouple insertion port not spot welding, side spot welding should pay attention to not to stop the welding screw;
3. The wall temperature of the pipeline should be installed symmetrically up and down;
4. The armored thermocouple must be inserted into place and the stop screw is in place;
5. It is recommended to use a small slot box for armored thermocouples.
6. Armored thermocouples must be replaced by stainless steel wire;
7. The interface between the armored thermocouple and the furnace wall must be wrapped, and then put into the self-made protective tube to lead out;
8, in order to prevent boiler settling, it is recommended to use a transition junction box, and then use the compensation wire to connect to the front-end;
9. The bridge or protection tube of the furnace wall and the front-end device should not be closed. It is necessary to prevent the high heat flow from directly entering the front-end device and damaging the components inside (the Tianjin Electric Power Construction has caused the front-end device because of no attention. damage);
10. The installation position of the front end device should not be too far, otherwise the length of the thermocouple is not enough;
11. the wiring should be correct and reliable.
