RH_Sensors

Resistive Sensors: Proven Technology for Tough, Condensing Environments Resistive humidity sensors work by using a moisture-sensitive material on an interdigitated electrode substrate. The device's resistance varies exponentially with variations in relative humidity. The main advantage of resistive technology for humidity sensors is that it is suited for use in varying, difficult, condensing environments.

Capacitive Sensors: The Solution for Aggressive Environments Capacitive humidity sensors ultilize conductive plates formed on a dielectric film. This forms a capacitor that is sensitive to the amount of water vapor in the air. The active portion of the sensor changes its dielectric constant as it absorbs atmospheric humidity, which varies the sensor's capacitance in proportion to changes in relative humidity. One benefit of capacitive sensor technology is that it's suited for use in chemically aggressive environments like the chlorinated air around swimming pools and the ammonia present in the air of many livestock facilities.

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Relative Humidity Sensors

The Phys-Chem EMD Series Resistive Relative Humidity Sensors EMD-2000 Chemical Resistance Chemical Ammonia Methanol Oil Acetone Hexane Formalin Condition 100% 15,000 ppm Immersion 1,000 ppm 1,000 ppm 1,000 ppm % RH Drift 5% RH 1% RH <1% RH 0% RH <1% RH <1% RH (25oC) EMD-2000 Characteristics The EMD-2000 sensor has exceptional chemical resistance. The table is a partial list of chemicals the sensor has been tested in. EMD-3000 Characteristics The EMD-3000 has remarkable hysteresis qualities. Hysteresis with the sensor is better than 1%. The compact size makes it ideal for many applications. Phys-Chem EMD-2000/3000 Series Properties Operating Range: - Humidity: 0% to 100% RH - Temperature: -40 to +100°C. Accuracy: +/-1%, +/-2%, +/-3%, +/-5% RH (Option) Frequency Range: 100 Hz. to 10 kHz., 40% to 80% RH. Typical Resistance Range: @ 20 to 90% RH, resistance is 5MW to 2.9 Kw. Average Temperature Coefficient: -0.3% RH/oC. Hysteresis: +/- 1% RH @ 25°C (EMD-2000) <1% RH @ 25°C (EMD-3000) Time Response: 15 seconds for a step change from 11% RH to 93% to reach 90% or better of equilibrium value. Dimensions: - EMD-2000 - 0.30" x 0.50" x 0.025" SIP package, 0.10" mounting centers - EMD-3000 - 0.20" x 0.40" x 0.02" SIP package, 0.10" mounting centers Power: Suggested Drive Voltage - 1VAC., peak to peak, sine or square wave recommented at 5,000 to 10,000 Hz.
The G-CAP2 Capacitive Relative Humidity Sensor G-CAP2 Properties Operating Range: - Humidity: 0% to 100% RH (condensing) - Temperature: -40 to +85°C. Capacitance Range: 148 pf +/-1pf @25°C, 0% RH, 10 kHz, (1 VRMS (calibrated version only) Frequency Range: D.C. to 1 MHz. Temperature effect: Less than 0.05% RH/°F. Hysteresis: Less than 2% RH Long Term Stability: Less than 0.5% drift per year typical Sensor Interchangeability: Better than +/-3% RH (calibrated version only) Time Response: 30 seconds typical, 45 seconds Max., 63% change for 25 ~ 75% step change. 150 LFM air flow. Material: Case - PBT plastic, 15% glass fill. Pins - Copper with 0.00001" min. tin plate Power: Maximum Voltage - 5 Volt (across sensor leads), 1 VRMS recommended
The APS-200 Capacitative Relative Humidity Sensor Chemical Testing Data @50% RH and 25°C. Chemical Swimming TSQ Germicide Ammonia 100% Formaldehyde Mixed Solvents Pool % RH Change <1% <2% <5% <5% <1.5% Phys-Chem EMD-2000/3000 Series Properties Operating Range: - Humidity: 0% to 100% RH - Temperature: -29 to +60°C. Norminal Capacitance Range: 218pf +/-22pf @ 50% RH, (25°C) and 10 kHz. Frequency Range: D.C. to 1 MHz. Typical Resistance Range: @ 20 to 90% RH, resistance is 5MW to 2.9 Kw. Temperature Coefficient: 0.22% RH/°C. Hysteresis: Less than 3% RH @ 25°C (40% to 80% RH) Long Term Stability: Less than 0.5% drift per year typical Time Response: 90 seconds typical -63% change for 20% to 80% RH. Power: Maximum Voltage: 5 Volts (1Volt, 10 KHz. recommented).
The RH-8 Bulk Polymer Resistive Relative Humidity Sensor RH-8 Properties Operating Range: - Humidity: 0% to 100% RH (condensing) - Temperature: 0 to +60°C. Accuracy: +/-5% RH. Frequency Range: 100 Hz. to 10 KHz. 40% to 80% RH. Typical Resistance Range: @ 20 to 90% RH, resistance is 5MW to 2.9 Kw. Temperature Coefficient: 0.3% RH/oC. Hysteresis: Less than 3% RH @ 25°C (40% to 80% RH) Long Term Stability: Less than 2% drift per year typical Time Response: 120 seconds for a change from @ an air flow velocity of 8 ft/s. Power: 1.4 VAC, 100 kHz. 0.2 mW AC power.