RH/T Transmitter Selection Guide: Accuracy, Output & Protection

Selecting an industrial RH/T transmitter involves more than meets the eye — accuracy class, output type, protection rating and mounting all matter. Four key dimensions:

1. Measurement Accuracy

±2%RH / ±0.3°C suffices for general HVAC; cleanroom and pharma applications need ±1.5%RH or even ±1%RH class. Note accuracy is typically specified at 23°C — check temperature drift for high-temperature, high-humidity sites.

2. Output Signal

4-20mA loop offers strong noise immunity and long transmission distance (hundreds of meters); 0-10V suits short runs; RS485 Modbus enables digital bus networking (up to 247 nodes) for centralized acquisition; wireless (LoRa/NB-IoT) fits hard-to-wire sites.

3. Ingress Protection

IP54 for general indoor; IP65 for server rooms and warehouses; IP66/IP67 or IP69K with anti-corrosion coating for food, pharma or wash-down environments.

4. Mounting

Wall-mount for rooms; duct-mount for supply/return air; probe for special structures; explosion-proof (Ex) for hazardous areas — verify the explosion group and gas classification.

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