Do you have a clear understanding of bimetal electrical contact thermometers?

Bimetal electric contact thermometers   

The bimetallic electrical contact thermometer is an industrial instrument that combines temperature measurement and automatic control functions.The biggest difference between it and an ordinary thermometer is that, in addition to indicating the temperature, it can also automatically control the circuit.                                

1. How to read the model number? The key parameters are all contained in the code.                                    
The model of a bimetallic electrical contact thermometer is usually composed of a prefix, main parameters, and additional functions. The national standard usually uses the "WSSX" series (W - temperature instrument, S - bimetal, S - electrical contact, X - additional function). Taking WSSX-411 as an example, the meanings of each part are clearly distinguishable:    

·Prefix (WSSX): Clearly indicates that the product type is a bimetallic electrical contact thermometer.

·The first digit (4): represents the installation method. 1 - Radial type (the dial is perpendicular to the insertion rod), 2 - Axial type (the dial is parallel to the insertion rod), 3 - Universal type (the dial can rotate 360°), 4 - Flange installation type, 5 - Threaded installation type.    

·The second digit (1): Indicates the diameter of the dial. Options are 1-60mm, 2-100mm, 3-150mm, 4-200mm. The larger the diameter, the clearer the reading, making it suitable for long-distance observation.

·The third digit (1): Indicates the accuracy level. 1 - 1.0 level, 2 - 1.5 level. The lower the accuracy level, the smaller the measurement error (for example, 1.0 level means the error is no more than ±1% of the range).     

·Additional code: For example, "P" indicates with protective pipe, "M" indicates with waterproof structure. The choice can be made according to the usage environment.   

2,The three core components determine the performance.                                    
The core of the bimetallic electrical contact thermometer is the coordinated design of "temperature measurement and temperature control", and it mainly consists of three parts:                                    

·Thermometric element (temperature sensing core): It is made by rolling together two metal sheets with different thermal expansion coefficients (such as brass and iridium alloy). When the temperature changes, the bimetallic sheet bends due to the difference in expansion, causing the pointer to rotate and achieving temperature indication.  

·Electrical contact device (key component for temperature control): It consists of fixed contacts and movable contacts. The movable contacts move along with the pointer. When the temperature reaches the preset value, the two contacts make contact/disconnect, triggering an external alarm or control circuit (such as starting the fan, shutting down the heater).  

·Head and mounting components: The head includes the dial, pointer and connection terminals, facilitating reading and wiring; the mounting components are divided into threaded (such as M27*2), flange (such as DN25) or socket type, suitable for the installation requirements of different devices.                                
                                    
3,Material selection:The materials of different components directly affect the temperature gauge's temperature resistance and corrosion resistance, and precise matching according to the working conditions is necessary.        

4,3 Steps to Select the Right Product                        

·Measurement range: Select based on the temperature range to be measured. It is recommended that the actual measurement falls within 1/3 to 2/3 of the range (for example, if measuring 0 - 100℃, choosing a range of 0 - 150℃ would provide more accurate results).                    

·Consider the environment: For humid/corrosive environments, choose stainless steel dial with 316L protective tube; for vibration scenarios, select the models with shock-proof structure.                    

·Installation: For pipe temperature measurement, use threaded or flange installation; for equipment temperature measurement, choose radial or universal type.                  

 Summary：                        
    Although the structure of the bimetallic electrical contact thermometer is not complex, the reasonable selection of models and materials directly affects the measurement accuracy and the safety of the equipment. We hope this article can help you quickly grasp the core knowledge and avoid selection mistakes. Have you encountered any problems in your use? Welcome to leave messages in the feedback section~