As a widely used temperature sensor, the accuracy class of the PT100 plays a crucial role in ensuring its precision and reliability across diverse industrial applications. When examining the accuracy classes of PT100 sensors, it is first necessary to understand the definition of accuracy class and its significance within the sensor industry.

I. Definition of Accuracy Class

The accuracy class is an indicator that quantifies the degree of deviation between a sensor’s measured value and the true value. It reflects the accuracy and reliability of the sensor’s measurements under specified operating conditions. Accuracy classes are typically expressed as an error range or an error percentage, helping users understand the potential margin of error when using the sensor.

II. Classification of PT100 Accuracy Classes

The accuracy classes of PT100 sensors can be classified according to various standards. Internationally, common accuracy class standards include Class A, Class B, and Class C. These accuracy classes specify different tolerance ranges to meet the requirements of diverse application scenarios.

1. Class A accuracy

PT100 sensors with Class A accuracy offer the highest measurement precision. Under standard operating conditions, the error of a Class A PT100 typically remains within ±(0.15 + 0.002|t|) °C, where t is the actual temperature in °C. Class A accuracy is suitable for applications that demand exceptionally high temperature‑measurement accuracy, such as precision laboratories, medical equipment, and high‑end manufacturing.

2. Class B accuracy

B‑grade PT100 sensors are slightly less accurate than A‑grade models, but they offer better cost performance and are suitable for most industrial applications. Under standard operating conditions, the error of a B‑grade PT100 typically falls within ±(0.30 + 0.005|t|) °C. B‑grade PT100s are widely used in temperature control systems, environmental monitoring, and process control, among other fields.

3. Class C accuracy

C‑class PT100 sensors offer relatively lower accuracy but are more affordable, making them suitable for applications where high temperature‑measurement precision is not required. Under standard operating conditions, the error of a C‑class PT100 typically falls within ±(0.60 + 0.01|t|) °C. C‑class PT100s are widely used in general industrial measurement, household appliances, and temperature monitoring, among other fields.

III. Selection and Application of Accuracy Classes

When selecting a PT100 sensor, users should determine the appropriate accuracy class based on the requirements of the specific application. Generally speaking, for applications demanding extremely high temperature measurement accuracy—such as precision laboratories and medical equipment—it is advisable to choose a PT100 sensor with Class A accuracy. For most industrial applications—including temperature control systems, environmental monitoring, and process control—a PT100 sensor with Class B accuracy is usually sufficient. Meanwhile, in scenarios where high temperature measurement accuracy is not critical—such as general industrial measurements, household appliances, and basic temperature monitoring—a PT100 sensor with Class C accuracy offers better cost‑effectiveness.

In addition to accuracy class, users should also consider other factors when selecting a PT100 sensor, such as measurement range, response time, stability, temperature‑range capability, and ingress protection rating. These factors collectively influence the sensor’s performance and reliability in practical applications.

IV. Factors Affecting the Accuracy Class of PT100 Sensors

The accuracy class of a PT100 is influenced by a variety of factors, primarily including the following aspects:

1. Material Purity: The purity of the materials used in PT100 sensors directly affects their resistivity and temperature coefficient, thereby influencing measurement accuracy. Consequently, strict control over material purity and composition is essential during the manufacturing process.
2. Manufacturing Process: The precision and stability of the manufacturing process significantly influence the accuracy class of PT100 sensors. Advanced process technologies and equipment must be employed during production to ensure the sensor’s stability and reliability.
3. Environmental Factors: In practical applications, PT100 sensors are subject to environmental influences such as temperature, humidity, and vibration. These factors can degrade sensor performance or cause damage, thereby compromising measurement accuracy. Therefore, when using PT100 sensors, it is essential to account for environmental effects and implement appropriate measures for protection and compensation.

What types of probes can be connected to a PT100 sensor?
PT100 sensors can be connected to the following main types of probes. Based on the relevant information in the reference article, the specific categories are summarized and described as follows:

Immersion-type probe:
Main applications: Measuring the temperature of liquids and solids.
Design features: The probe tip is designed in a needle-like shape to facilitate penetration into the test object.
Precautions:
When the probe’s temperature is lower than that of the object being measured, heat flows from the object to the probe; conversely, heat flows from the probe to the object under test.
Ways to reduce measurement error include ensuring that the insertion or immersion depth is 10 to 15 times the probe diameter, and, when the medium being measured is a liquid, keeping it as still as possible.

Air temperature probe:
Main applications: Measuring air temperature; commonly used in cold storage facilities, refrigerated display cases, air-conditioned rooms, and ventilation areas.
Design feature: The probe is exposed to the ambient air, making it susceptible to disturbances caused by airflow.
Solution: At an air velocity of 2–3 m/s, gently move the probe downstream to allow the temperature to reach equilibrium and stabilize.

Surface probe:
Main application: Measuring the surface temperature of objects.
Instructions for use: Position the probe tip perpendicular to the surface of the object being measured and ensure tight contact.
Precautions: The contact surfaces of the probe and the test object must be flat; otherwise, measurement errors may easily occur.

Waterproof temperature probe (e.g., Pt100 temperature sensor, platinum resistance thermometer WZP-187 waterproof temperature probe, K/E‑type thermocouple temperature sensing rod):
Key features: Waterproof design, suitable for temperature‑measurement environments requiring water‑proof protection.
Medium-Temperature Platinum Resistance PT100/PT1000 Temperature Sensor Temperature Probe:
Applicable environment: Suitable for ambient temperature measurement in environments with long-term operating temperatures around 200°C.
Accuracy and Grade: Depending on the grade (e.g., Grade A, Grade B), different accuracy requirements apply.
Application scenarios include temperature measurement and control in heating/cooling pipelines of central air-conditioning units, as well as in refrigerators, freezers, bearing shells, cylinder blocks, oil lines, water pipes, steam lines, textile machinery, flat‑bed equipment, air conditioners, water heaters, thermometers, and other industrial devices operating in confined spaces. They also encompass atmospheric environmental monitoring, industrial process control, and instrumentation.
All of the aforementioned probe types can be used with PT100 sensors; the specific choice depends on the particular application and measurement requirements.