New Test Method for Measuring Humidity with Resistive Hygrometers
1. Scope
This test method will cover the measurement of ambient humidity using electrical impedance and resistance sensors, including bulk hygroscopic polymer and salt-based (e.g., lithium chloride) elements. It will specify procedures for their operation, signal conditioning, and calibration. The method will also detail operational limitations, specific temperature dependencies, and protocols for avoiding damage from liquid water exposure (washout).
Resistive sensors are highly sensitive and cost-effective, with a long history of use in upper-air meteorology (radiosondes) and specific ground-based applications. They exhibit distinct hysteresis and degradation profiles compared to capacitive sensors. A standard is required to outline these specific limitations, calibration drift profiles, and proper handling to ensure data comparability across different measurement campaigns. Users include upper-air meteorologists, agricultural scientists, and climate researchers.