Humidity

Microwave moisture measurement

Microwaves penetrate the bulk material, causing a rotation of the free water molecules. As a result the velocity of the microwaves is reduced (phase shift) and their intensity is weakened (attenuation). Both effects are measured and used to calculate moisture content.

These measuring effects are achieved with very small microwave transmission power – typically 0.1 mW. Consequently the measured material is neither warmed nor modified. Factors such as colour, viscosity, composition homogeneity, and dust have no or only a negligible effect on the measurement performance.

Radiometric moisture measurement

Fast neutrons are slowed down impacts with hydrogen nuclei, but are barely affected by other elements.
This measurement system comprises a source, emitting a cloud of fast neutrons. After their interaction with the water molecules within the measured material, the attenuated neutrons are measured by a detector that is only sensitive to slow neutrons. As the number of slow neutrons corresponds to the hydrogen content, radiometric neutron technology provides an extremely reliable measurement of product moisture or hydrogen content. 
It is not affected by temperature, pressure, conductivity, or varying particle sizes, and even frozen water can be measured reliably.

Measure humidity in harsh environments with the best-in-class instrument you can truly depend on. The Vaisala HUMICAP Humidity and Temperature Transmitter Series HMT330 is designed for demanding industrial applications where stable measurements and extensive customization are essential. With multiple options to choose from, instrument can be tailored to meet the specific needs of each individual application and is pre-configured for each delivery. We offer a 10-year warranty* on new HMT330 transmitters.

For Demanding Low Humidity Conditions

Condensation-resistant DMT340 is designed for industrial low-humidity applications such as industrial drying, compressed air systems, semiconductor industry, dry rooms, baking ovens, and metal heat treatment to provide accurate and reliable measurement.