www.ahlborn.com 0 o HUMIDITY The Right Humidity Sensor for Any Measuring Task For humidity measurements various methods are used that differ from each other mainly with regard to their accuracy and their suitability for long term measurements and the substance used for the measurement: ► Capacitive Air Humidity Measurement, ► Psychrometric Air Humidity Measurement, ► Hygrometric Air Humidity Measurement, ► Dielectric Measurement of Moisture in Materials, ► Measurement of the Moisture in Materials According to the Principle of Conductivity, ► Dew Point Determination with CCC Dew Point Probes, ► Dew Point Determination with Dew Point Mirrors. Capacitive Air Humidity Measurement Capacitive sensors contain a glass substrate with a moisture sensitive polymer layer between two metal layers. By absorption of water, corresponding to the relative humidity, the dielectric constant and, as a result, the capacity of the thin-film capacitor are changing. The measuring signal is directly proportional to the relative humidity and does not depend on the atmospheric pressure. Advantage: ► maintenance-free measurement over longer periods, can withstand temperatures below 0°C ► atm. pressure-independent, works when pressure is applied ► flexible use of the sensor Disadvantage: ► limited long term stability ► sensitive to dewing and certain aggressive substances Psychrometric Air Humidity Measurement Psychrometers are precision devices containing a dry and a moistened temperature sensor. As a result of the evaporation the humidity sensor cools down, with a wind velocity of a minimum of 2m/s being required for the cool down process. The humidity values are calculated from the temperature difference (psychrometric difference). The calculation formulae for ALMEMO® devices correspond to those used by the German Weather Authority related to 1013mbar. Differences regarding to the atmospheric pressure can be corrected to achieve precise measurements. Advantage: ► no ageing of the sensor -exception: contamination of the wick ► high accuracy ► high quality regarding the measuring technology ► usable without problems up to 100% r.H. in all substances Disadvantage: long term measurement limited by the required water reserve and wick maintenance difficult to use with temperatures below 0°C and with low humidities ► depending on the atmospheric pressure 09.02 s. e g n a ch al ic ni ch te e k a m to igh e e vr er s re e W 0 0 /2 Hygrometric Air Humidity Measurement Hygrometric sensors are equipped with a measuring strip, which lengthens or tightens depending on the humidity. The measuring strip consists of many single fibers (measuring harp), which are made from organic or synthetic material. Advantage: ► simple and low cost measuring technology, also usable for contaminated environments ► easy to clean Dielectric Measurement of Moisture in Materials Disadvantage: ► limited accuracy ► limited measuring range ► slow measurement The measurement of the moisture in materials is performed indirectly via the determination of the dielectric constant. This is performed by using a capacity measurement via a high-frequency electrical field, which penetrates the material without disturbances. Advantage: ► simple and fast measuring technology ► non-destructive contact measurement ► long term use is possible Disadvantage: ► limited accuracy 10

HUMIDITY Measurement of the Moisture in Materials according to the Principle of Conductivity The measurement of the moisture in materials is performed indirectly via the determination of the electrical rsistance, which dpends on the moisture content of the material. g 2 o o -j CD e r v CD e gh o m QJ CD Advantage: ► simple and fast measuring technology Disadvantage: ► limited accuracy ► probe insertions ► only for short term control measurements ► measured values depend on various material parameters Dew Point Determination with CCC Dew Point Probes The dew point sensor is equipped with an integrated...

www.ahlborn.com 0 0 HUMIDITY Capacitive humidity sensor Typ FHA646-E1 / -E1C / -E2C / -E3C Technical data : Operative range: FHA646-E1 FHA646-E1C / -E2C / -E3C -20 to +60 °C/ 5...98 % r.H. -20 to +80 °C/ 5...98 % r.H. Humidity measuring circuit Measuring range : 0 to 100 % r.H. Sensor : capacitive Accuracy : ± 2 % r.H. at nominal temperature Reproducibility : <1 % r.H. at nominal temperature Nominal temperature : +25 ± 3 °C Sensor operating pressure : atmospheric pressure Response time T90 : approx. 10 seconds (without filter) at 5 m/s Temperature measuring circuit Sensor : NTC type N Accuracy...

HUMIDITY Capacitive humidity sensor Type FHA646KxC 1 Technical data : Operative range : -20 to +80 °C/ 5 to 98 % r.H. Humidity measuring circuit : Measuring range : 0 to 100 % r.H. Sensor : capacitive Accuracy : ± 2 % r.H. at nominal temperature Reproducibility : <1 % r.H. at nominal temperature Nominal temperature : +25 ± 3 °C Sensor operating pressure : atmospheric pressure Response time T90 : approx. 10 seconds (without filter) at 5 m/s Temperature measuring circuit Sensor: NTC type N Accuracy : -20 to 0°C: ±0,4°C 0 to 70°C: ±0,1°C 70 to 80°C: ±0,6°C Reproducibility : 0,1°C Mechanical design...

www.ahlborn.com 0 o HUMIDITY Protective caps for capacitive humidity sensors Type FHA646-Elx/-KxC/-E7C/-5x Dimensions : length approx. 33 mm, diameter 12 mm Types : Designation Pore-size Maximum temperature Typical Application Type SK7 Metal-mesh filter in PC-housing 100 pm 120°C Universal, for medium, contamination, also high humidity Order No. ZB9600SK7 SK6 PTFE-Sinterfilter 50 pm 180°C High chemical resistance Order No. ZB9600SK6 SK8 Stainless steel sinter filter 10 pm 180°C For severe mechanical stress, heavy contamination, Order No. ZB9600SK8 strong air flow Brackets for wall mounting Brackets...

HUMIDITY Capacitive Humidity Sensor Type FHA6466 Technical Data: Operative range : -20 to +60 °C / 5 to 98 % r.H. Humidity Measuring Circuit Measuring range: 0 to 100 % r.H. Sensor: capacitive Accuracy: ±2% r.H. at nominal temperature Reproducibility: < 1% r.H. at nominal temperature Nominal temperature: 25°C ±3°C Sensor operating pressure: atmospheric pressure Response time T90: approx. 10s (without filter) at 5m/s Temperature Measuring Circuit Sensor: NTC type N Accuracy: -20 ... 0°C: ±0.4°C 0 ... 60°C: ±0.1°C Reproducibility: 0.1°C Slotted case plastic, 30 x 11 x 7.6 (without filter) 01 2...