In the field of industrial temperature measurement, platinum resistance sensors are widely used due to their high accuracy and stability. Fixed flange-type probe platinum resistance sensors and movable threaded-mount probe platinum resistance sensors are two common installation types, and they differ significantly in structure, installation method, applicable scenarios, and maintenance requirements. The following analyzes the differences between the two in detail from multiple dimensions.
Differences in Structure and Installation Method
The fixed flange-type probe platinum resistance sensor uses a flange connection structure, rigidly fixing the sensor flange to a standard flange (such as DN25 PN1.6) on the pipe or equipment with bolts. Its mounting surface is flat and requires a sealing gasket to achieve media isolation, ensuring sealing and stability in high-pressure, high-temperature, or high-vibration environments. This structure usually features an integral metal casing, with the hot end extending into the medium and the cold end having a reserved junction box. It has high overall rigidity and strong resistance to deformation, making it suitable for long-term fixed installation.
The movable threaded-mount probe platinum resistance sensor is directly screwed into the pre-drilled threaded hole of the equipment using a standard threaded interface (such as M12×1.5, G1/2), relying on thread engagement and a sealing ring for sealing. Its structure is compact, the probe length can be customized, and installation does not require additional flange components, making operation convenient. The movable threaded design supports disassembly and adjustment of the insertion depth, facilitating maintenance and calibration, and is suitable for applications requiring frequent replacement or adjustment.
Core Differences Comparison
|
Feature |
Fixed Flange Type |
Movable Threaded Installation Type |
|
Fixing Method |
Rigid bolt fixing, flange surface contact |
Threaded connection, line contact |
|
Sealing Method |
Flange surface + gasket |
Thread + O-ring |
|
Main Advantages |
Good sealing performance, strong vibration resistance, suitable for harsh environments |
Convenient installation and removal, adjustable insertion depth |
|
Typical Application Scenarios |
High pressure, high temperature, strong vibration environments (e.g., reactors, boilers) |
Medium and low pressure pipelines, applications requiring maintenance or adjustment |
|
Maintenance Convenience |
Lower, requires removal of flange bolts |
Higher, allows for quick disassembly and replacement |
Applicable Working Conditions and Industry Applications
The fixed flange type is suitable for high-pressure systems (≥1.6MPa), high-temperature environments (-200℃~850℃), and strong vibration scenarios, such as the petrochemical, nuclear power, metallurgy, and thermal power boiler industries. Its sealing and vibration resistance make it the preferred choice for safety redundancy design in high-pressure systems, but it has a lower maintenance frequency and is mostly used for long-term fixed installation.
The movable threaded installation type is suitable for medium and low-pressure pipelines (≤1.6MPa), conventional industrial pipelines, and applications requiring regular calibration or replacement, such as mechanical manufacturing, food and pharmaceutical, and HVAC industries. Its convenient installation and removal make it a mainstream economical and general-purpose solution, suitable for space-constrained or applications requiring quick maintenance.
Performance Parameters and Selection Points
Accuracy Class: Both comply with IEC 60751 standard, commonly A-class (±0.15℃) and B-class (±0.30℃), with no essential difference.
Thermal Response Time: The fixed flange type is slightly slower due to the thermal inertia of the flange (10s~40s), while the movable threaded type responds faster due to its lightweight structure (3s~10s).
Protection Class: The fixed flange type is mostly custom-engineered, and the protection class depends on the flange sealing design; the movable threaded type is widely available on the market, commonly IP65~IP68, supporting corrosion resistance (316L stainless steel) and explosion-proof (Ex d IIC T6).
Wiring Methods: Both three-wire (industry standard) and four-wire (high-precision laboratory) configurations are supported. Two-wire configuration is only suitable for high-resistance models such as PT1000.
Selection Suggestions and Precautions
For fixed flange type: Suitable for harsh environments with high pressure, high temperature, strong vibration, or requiring long-term stable operation. During installation, ensure the flange surfaces are parallel and the bolts are tightened evenly diagonally to avoid uneven loading.
For movable threaded mounting type: Suitable for medium and low pressure applications, where periodic calibration, replacement, or limited space is required. During installation, clean the threaded hole, apply thermal conductive grease, and control the tightening torque to prevent stripping the threads.
Summary: The core difference between fixed flange type and movable threaded mounting type probe-type platinum resistance thermometers lies in the connection mechanism and applicable scenarios. The fixed flange type is rigidly fixed by a flange plate and bolts, suitable for high-pressure, high-temperature, and strong vibration environments; the movable threaded mounting type connects through a threaded interface, allowing for disassembly and adjustment, suitable for medium and low-pressure pipelines and applications requiring frequent maintenance. When selecting a model, a comprehensive assessment should be made based on actual working conditions, maintenance requirements, and installation space to ensure the most suitable model is chosen.
