Industrial thermistorIt is a commonly used temperature detection sensor in low-temperature areas of the industrial field, which achieves temperature measurement based on the characteristic of the resistance value of metal or semiconductor materials changing with temperature. The core principle is that as the temperature increases, the internal lattice vibration of the material intensifies, leading to enhanced electron scattering and an increase in resistance value (such as positive temperature coefficient materials like platinum and copper); Some semiconductor materials exhibit negative temperature coefficient characteristics. This physical characteristic makes it a core component for high-precision temperature measurement in the range of -200 ℃ to 850 ℃.
Industrial thermistorThe main maintenance methods are:
1、 Daily inspection and monitoring
Observe the operating status
Regularly check the temperature readings of the thermal resistance on the control system (such as DCS, PLC, or transmitter) to ensure they are normal and stable.
Pay attention to any abnormal phenomena such as jumping, drifting, or fixed values (such as displaying maximum or minimum values), which may be caused by sensor faults, loose wiring, or interference signals.
Check the installation environment
Confirm whether the working environment of the thermistor (temperature, pressure, corrosive media) is still within its design allowable range.
Check the protective tube for deformation, cracks, severe corrosion, or wear.
For thermal resistors inserted into pipelines or equipment, pay attention to whether the process medium may cause blockage (such as viscous media, crystallization).
Check the junction box
Regularly open the junction box (during safe shutdown) and check:
Are the wiring terminals securely fastened, free from looseness, oxidation, or corrosion.
Whether the insulation layer of the wire is intact, whether there is aging or damage.
Is the box dry, clean, and free of accumulated water, oil stains, or dust. If any, it is necessary to clean and identify the cause of the water ingress.
2、 Regular maintenance (recommended every 6-12 months or as per equipment requirements)
Cleaning and anti-corrosion
Clean the exposed parts of the thermistor (such as junction boxes, protective tube flanges) of dust and oil stains.
Check the anti-corrosion condition of the coating or material on the surface of the protective tube, and promptly handle or replace severely corroded areas.
Check the sealing performance
Check the sealing ring of the junction box cover for aging, deformation, or damage to ensure its waterproof and dustproof (IP rating) performance.
Check if the sealing gasket or O-ring at the connection between the protective tube and the process is intact to prevent medium leakage.
Calibration and Verification
Regular calibration: Remove the thermistor from the process and send it to the metrology department or use a standard constant temperature bath for periodic calibration (usually once a year). This is a crucial step in ensuring measurement accuracy.
On site comparison: When disassembly is not possible, a calibrated portable thermometer (such as an infrared thermometer, suitable for surface temperature measurement) or a temporarily inserted standard thermistor can be used for on-site comparison to verify its reading accuracy.
Check the leads and cables
Check for mechanical damage, indentation, and aging of the compensating wires or cables from the junction box to the control system.
Ensure that the shielding layer of the shielded cable is well grounded to reduce electromagnetic interference.
3、 Special case handling
Dealing with harsh working conditions
High temperature/high pressure: Ensure that the selected protective tube material and wall thickness meet the requirements, and regularly check its strength.
Corrosive medium: Choose corrosion-resistant materials (such as 316L stainless steel, Hastelloy, ceramics) for the protective tube. If corrosion is found to have worsened, the inspection cycle should be shortened or replaced in advance.
Wear resistant media (such as fluids containing particles): Consider using thickened protective tubes or replaceable protective sleeves.
Vibration environment: Check whether the installation bracket is firm to avoid fatigue fracture of the protective tube or loose wiring caused by long-term vibration.
Risk of icing or blockage
In low-temperature or easily crystallized environments, check the insertion depth and position of the protective tube, and take insulation or heat tracing measures if necessary to prevent the medium from solidifying and blocking inside the casing.
4、 Maintenance during shutdown and long-term disuse
Cut off the power completely
Cut off the power supply of the measurement circuit during equipment overhaul or long-term shutdown.
Protective storage
If removed for storage, it should be cleaned thoroughly, and the protective pipe interface should be sealed with a plug to prevent dust or foreign objects from entering.
Store in a dry, non corrosive gas environment.