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WRP-230 fixed thread platinum rhodium thermocoupleHigh temperature oxidation resistance | Stable performance with precise measurement | Resistant to harsh environments | Good interchangeability |
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Product Overview/Product overview-----------------------------------------------------------◆◆ |
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| Industrial platinum rhodium thermocouples, also known as precious metal thermocouples, are commonly used as temperature measurement sensors in conjunction with temperature transmitters, regulators, and display instruments to form process control systems. They are used to directly measure or control the temperature of fluids, vapors, gas media, and solid surfaces within the range of 0-1700 ℃ in various production processes. Platinum rhodium thermocouple is composed of two conductors with different compositions connected at both ends to form a circuit. When the temperature of the two junction points is different, a thermal current will be generated in the circuit. If there is a temperature difference between the working end and the reference end of the thermocouple, the display instrument will indicate the temperature value corresponding to the thermoelectric potential generated by the thermocouple. The thermoelectric heating of a platinum rhodium thermocouple will increase with the temperature at the measuring end, and its size is only related to the thermocouple material and the temperature at both ends, and is independent of the length and diameter of the thermoelectric electrode. The appearance of various platinum rhodium thermocouples is often very different due to needs, but their basic structures are roughly the same, usually composed of main components such as hot electrodes, insulation sleeves, protective tubes, and junction boxes. | |||||||||||||||||||||||||||||||||||||||||||||||||
Working principle/operational principle--------------------------------------------------------◆◆ |
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| Two conductors with different compositions are welded at both ends to form a circuit. The temperature measuring end is called the measuring end, and the wiring terminal is called the reference end. When there is a temperature difference between the measuring end and the reference end, a thermal current will be generated in the circuit. When connected to a display instrument, the instrument will indicate the corresponding temperature value of the thermoelectric potential generated by the thermocouple. | |||||||||||||||||||||||||||||||||||||||||||||||||
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Working principle diagram of thermocouple |
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Technical parameters/Technical parameters-------------------------------------------------------◆◆ |
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| ★ Temperature measurement range and allowable error | |||||||||||||||||||||||||||||||||||||||||||||||||
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| ★ Stability | |||||||||||||||||||||||||||||||||||||||||||||||||
| Stability refers to the degree of change in the thermoelectric characteristics of a thermocouple over time of use, and is an important indicator reflecting the service life of the thermocouple. It is a destructive testing requirement that is only conducted during product type testing. The specific regulation is that after maintaining the upper limit temperature of the thermocouple for 250 hours of long-term use, the change in thermoelectric potential shall not exceed 50% of the total deviation in measurement accuracy. The stability requirement index for N-type Level II precision is: after maintaining at 1200 ℃ for 250 hours, the change in thermoelectric potential before and after the thermocouple test should be less than 9 ℃ (1200 × 0.75%). | |||||||||||||||||||||||||||||||||||||||||||||||||
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| ★ Thermal response time | |||||||||||||||||||||||||||||||||||||||||||||||||
| When there is a step change in temperature, the output of the thermocouple changes to 5% of the change, and the time required is called the thermal response time, represented by T0.5. | |||||||||||||||||||||||||||||||||||||||||||||||||
| ★ Nominal pressure of thermocouple | |||||||||||||||||||||||||||||||||||||||||||||||||
| Generally refers to the static external pressure that the protective tube can withstand at working temperature without breaking. In fact, the allowable working pressure is not only related to the material, diameter, and wall thickness of the protective tube. It is also related to its structural form, installation method, insertion depth, as well as the flow rate and type of the measured medium. | |||||||||||||||||||||||||||||||||||||||||||||||||
| ★ Minimum insertion depth of thermocouple | |||||||||||||||||||||||||||||||||||||||||||||||||
| It should not be less than 8-10 times the outer diameter of its protective tube (except for special products). | |||||||||||||||||||||||||||||||||||||||||||||||||
| ★ Insulation resistance of thermocouple (at room temperature) | |||||||||||||||||||||||||||||||||||||||||||||||||
| The test voltage for room temperature insulation resistance is DC 500V ± 50V. The atmospheric conditions for measuring room temperature insulation resistance are temperature 15-35 ℃, humidity 45%, and atmospheric pressure 86-106kPa. a、 For thermocouples with a length exceeding 1 meter, the product of their insulation resistance at room temperature and their length should not be less than 100M Ω. m. That is, Rr. L ≥ 100 Ω. m L ≥ 1m In the formula: Rr - insulation resistance value of thermocouple at room temperature, M Ω L - Length of thermocouple, m. b、 For thermocouples with a length of 1 meter or less, their insulation resistance at room temperature should not be less than 100M Ω. |
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★ Upper limit temperature insulation resistance The upper limit temperature insulation resistance of the thermocouple should not be less than the specified value in the table below: |
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| Selection Instructions for Precious Metal Thermocouple Temperature Measuring Components | |||||||||||||||||||||||||||||||||||||||||||||||||
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Structure of thermocouple/structure of thermocouple----------------------------------------------◆◆ |
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| From the temperature measurement principle of thermocouples, it can be known that in addition to the two thermoelectric electrode materials, the most basic thermocouple must also be made into measuring and reference ends at both ends of the thermoelectric electrode according to requirements, commonly known as the "hot end" and "cold end", which are the so-called "two ends". According to the different uses of thermocouples, there are four forms of the hot end: insulated, multi branch insulated, shell connected, and exposed. The cold end has two forms: sealed and unsealed. Thermocouples are generally composed of five parts, with two thermoelectric electrodes (or wires) being the core part of the thermocouple (the first part being the temperature measuring element), and the other parts surrounding it; In order to ensure that the thermoelectric potential in the circuit is not lost and the measured temperature signal is accurately transmitted, it is necessary to use insulation materials to provide reliable insulation between the two thermoelectric electrodes except for the two end points, as well as between them and the outside world (the second part of insulation materials); In order to protect the insulation material and thermocouple wires and extend the service life of thermocouples, protective sleeves (Part III protective sleeves) are generally designed; In order to facilitate installation and wiring, and to adapt to various usage scenarios, a fourth part wiring device and a fifth part installation fixing device are generally designed. These are the so-called 'Five Parts'. According to different purposes, the most basic thermocouple (i.e. thermocouple core) that can measure temperature does not have protective tubes or fixed installation devices. Prefabricated thermocouples are mainly composed of a junction box, protective tube, insulating sleeve, terminal block, and thermoelectric electrode, and are equipped with various installation and fixing devices. |
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Product selection/product selection------------------------------------------------------------◆◆ |
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Model specifications/specifications---------------------------------------------------------------◆◆ |
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Product Selection/Product Selection ------------------------------------------------------------------ |
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