Temperature and humidity sensor selection and application skills - Solutions - Huaqiang

Kaixin micro test

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Test probe PH-5H

When selecting a temperature and humidity sensor, it's essential to focus on the measurement range and accuracy. Additionally, factors like time drift and temperature drift should be considered. Since humidity sensors are typically not sealed, they must be protected from acidic, alkaline, or organic solvent environments to maintain accuracy and stability.

1. Choose the Measurement Range

Similar to measuring weight or temperature, the first step in selecting a humidity sensor is determining the required measurement range. Most applications don’t need full-range (0–100% RH) measurements unless in specialized fields like meteorology or scientific research.

2. Select the Measurement Accuracy

Accuracy is one of the most critical parameters for a humidity sensor. Each 5% increase in precision can significantly impact performance and cost. Users should avoid blindly pursuing high-end models unless necessary. Temperature changes can affect humidity readings—just a 0.1°C shift may cause a 0.5% RH error. In environments without stable temperatures, ±5% RH is usually sufficient. For precise control, ±3% RH or higher is recommended. However, achieving ±2% RH is extremely difficult, even for standard calibration devices.

3. Consider Time Drift and Temperature Drift

Over time, humidity sensors can degrade due to exposure to dust, oil, or harmful gases. Annual drift often ranges between ±2% and higher. Manufacturers usually recommend recalibration every 1–2 years to maintain accuracy.

4. Additional Precautions

Non-sealed humidity sensors must be kept away from corrosive environments and dusty areas. They should also be placed in open spaces with good air circulation, not near walls or corners. For large rooms, multiple sensors are recommended. Some sensors have strict power requirements, and signal interference or long-distance transmission can affect performance. For distances over 200 meters, frequency output sensors are advised.

Other selection criteria include environmental conditions, output types, installation methods, gas compatibility, materials, control needs, and safety hazards. Cost-effectiveness, maintenance, and reliability are also important factors.

Cost-effective options should balance price, lifespan, maintenance, and calibration costs. Calibration ease is crucial—even for low-precision applications. Ruggedness is important, as sensors must withstand extreme conditions like condensation, dust, and chemicals.

Quality and reliability depend on the manufacturer’s reputation and product history. Brand-name products often offer better performance than generic ones. Adaptability and replaceability are key when using multiple instruments. Spare parts and after-sales support ensure long-term usability and peace of mind.

Choosing the right temperature and humidity sensor can boost efficiency, reduce workload, and improve overall performance in your operations.