How to Select a Temperature Transmitter

Determine the measurement range:

The temperature transmitter selection is based on the highest/lowest temperature of the measured medium (e.g., -200°C to 1600°C). It is recommended that the actual measurement value falls within the 1/3 to 2/3 range of the measurement range (e.g., for measuring a medium at 80°C, a 0 to 150°C measurement range can be selected).

Select the sensor type:

Match based on the temperature measurement range and accuracy requirements. Common types are compared as follows:

Thermocouple (Type K) | -270°C to 1370°C | High temperature resistance, fast response, low cost | High-temperature environments (e.g., boilers, furnaces) |

Thermocouple (Type S) | 0°C to 1700°C | High accuracy, good stability | High-precision high-temperature measurement (e.g., laboratories) |

Thermoresistor (PT100) | -200°C to 650°C | High accuracy, good linearity, excellent low-temperature performance | Ambient/medium-temperature precision measurement (e.g., pipes, equipment)

Thermoresistor (Cu50) | -50°C to 150°C | Low cost, good linearity | Ambient-temperature residential applications (e.g., air conditioners, water tanks) |

Determine the output signal:

Match with the backend control system. The mainstream options for the temperature transmitter are 4–20 mA analog signals (strong anti-interference, long transmission distance) or RS485 digital signals (supports multi-device networking, such as Modbus protocol).

Consider the installation method:

Confirm in advance whether it is threaded installation (e.g., M27×2), flange installation (e.g., DN25), or insertion type to avoid mismatch with the on-site interface.

Adapt to environmental conditions:

Ambient temperature: High-temperature environments require models with heat sinks; low-temperature environments require models with low-temperature-resistant circuit designs;

Protection rating: Humid/dusty environments require IP65 or higher; explosive environments must comply with explosion-proof ratings (e.g., Ex d IIB T4 Ga).

For details, please contact Qi Huang: qihuang@utopsensor.com