Problems with temperature measuring instruments
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I have a few questions for everyone: (1) According to clause 4.3.1 of the \"Specifications for the Selection and Design of Automated Instruments\" (HG20507-2014), when measuring the temperature of detection equipment, the outer walls of pipes, and the surfaces of rotating components, surface (terminal) type, spring-mounted type, cable-type, or armored thermoresistors and thermocouples are recommended. 1.1 Are surface thermal resistors and terminal thermal resistors the same thing? Are end-type thermistors included with the complete set of units? 1.2 Does the surface thermal resistance also include those with compression springs for fixation? How to choose between spring-mounted and directly welded installation methods? 1.3 How does a wire-type sensor measure surface temperature? I couldn’t understand the sample from Cologne. (2) Besides the following two situations, in what other cases is it necessary to use a conical, integral drilling protection sleeve? a) Steam media with high flow rates, such as medium-pressure steam and superheated steam. b) The case of two-phase flow. (3) According to Article 4.2.4 of the \"Specifications for the Selection and Design of Automated Instruments\" (HG20507-2014), \"for applications in low temperatures below -80°C where close observation is not possible, where there is vibration, and where high accuracy is not required for local or panel-mounted displays, pressure-type thermometers can be used.\" The capillary of a pressure-type thermometer should be protected, and its length should be less than 10 m. Some samples state that the pressure thermometer can measure temperatures down to -200°C; the WIKA website also indicates that it is capable of measuring up to -200°C, but the actual range specified for these instruments is only -80°C. The JJG310-2002 standard for the calibration of pressure thermometers also specifies -80°C as the maximum measurable temperature. Has anyone used such instruments in environments with temperatures below -80°C?
Pay attention, it’s the right time to learn*learn*......
LNG temperature: -162, liquid nitrogen temperature: -196
I have seen on-site measurements of shell temperature, and thermistors are used for that.
I have seen face-mounted thermocouples, which are thermocouples in the form of armored thin sheets that are fixed directly on the surface or end face of the equipment.
Cable-type resistance thermometers and thermocouples are used to measure surface temperature. After checking, it seems that these were added in the 2014 version; I’m not entirely sure about this either... WIKA states that cable resistance thermometers are particularly suitable for applications where the metallic sensor tip is installed directly into drilled holes (for example, in machine components), or directly into the process fluid, in any application where there are no chemically aggressive substances or abrasive conditions. Alternatively, you could send an email to the person who drafted the specifications ;)
Both surface thermal resistors and terminal thermal resistors are thermal resistors