Description
Water Activity Meter – Humimeter RH2 Description
Water activity indicates the amount of unbound water (free water) in a material. It is an important factor in food preservation and quality control – for example, for the shelf life of meat or other foods. This quality factor, also known as the aw value, depends on the water vapour pressure in the material, the current temperature and the water vapour pressure of the environment.
The humimeter RH2 water activity meter enables the quick and easy determination of water activity. We offer two different sensors for this purpose:
- Due to the large sample volume, larger quantities can be measured in the measuring chamber within a short time. This allows for a higher number of samples drawn.
- The measuring cell, in turn, is used for very small sample quantities. In addition, the sensor is replaceable here.
- Many materials such as butter, fruit mixtures, spices, granules, PVC, mushrooms, xylitol or even seasoning can be measured.
With our aw value meter for food, the shelf life can be secured and controlled.
The measuring device is a laboratory device and allows measurements to be made in accordance with EN ISO 21807.
In the download area you will find the instructions for calibration and adjustment of the water activity meter humimeter RH2.
FAQ:
What is water activity?
Water activity is a measure of the free water available in a substance or product and its ability to promote the growth of microorganisms such as bacteria, yeast, and mold. It is defined as the ratio between the vapor pressure of water in a substance and the vapor pressure of pure water at the same temperature, and is expressed as a dimensionless value between 0 and 1.
Why is the aw-value measuring device important for food?
Water activity is an important factor in food preservation and quality control. Foods with high water activity, such as fresh fruits and vegetables, are more susceptible to spoilage and decomposition because the water in the food provides an ideal environment for microorganisms to grow. In contrast, foods with low water activity, such as dried fruits, have a much longer shelf life because the low water activity makes it difficult for microorganisms to grow.
Is the aw-value measuring device also applicable to meat?
Yes, the humimeter RH2 aw-value meter is used for meat. Fresh meat has the highest water activity. Preservation reduces the availability of moisture for the microorganisms.
What is equilibrium moisture?
Equilibrium moisture is the moisture content that a material or substance absorbs and maintains at a given temperature and relative humidity when it is in a stable state. As the relative humidity rises, the material absorbs moisture until it reaches its equilibrium. When the relative humidity drops, the material releases moisture until it regains its equilibrium.
What is the optimal aw value?
The optimal value depends on the product. Each food has its own limit values that determine when mold formation is possible.
Advantages
- aw value, relative humidity, absolute humidity, dew point, equilibrium humidity
- Fast adjustment behaviour
- Long-term stable humidity and temperature sensors
- Easy data storage on the portable moisture meter
- Optimal documentation of quality
- portable handheld device
- High measurement accuracy
Specifications
| Relative humidity | Measuring range according to sensor, resolution 0.1 % R.H. |
|---|---|
| Temperature | Measuring range according to sensor, resolution 0.1 °C |
| Dew point | -55 to +60 °C, -67 to 140 °F |
| Absolute humidity | 0 to 130 g/m³, resolution 0.1 g/m³ |
| Ugl. Equilibrium wood moisture | 2 to 30%, resolution 0.1% |
| Ugl. Plastic granules equilibrium moisture | Resolution 0.01% |
| aw value | 0.0 to 1.0, resolution 0.001 |
| Memory function | Online function, hold function, manual measured value memory |
| Car Data Logger | 10,000 values with measurement location description |
| Dimensions basic unit | 145 x 75 x 30 mm |
| Weight | 210 g (incl. batteries) |
| Power supply | 4 Alkaline AA Batteries 1.5 V |
| Menu languages | German, English, Italian, French, Spanish, Portuguese, Czech, Polish, Russian, International |
Learn more
The ease of use guarantees cost-saving and error-free measurement of the activity of the water value of food. Simply fill the material into the aw value chamber and close it.
After an appropriate conditioning time (period until a constant climate in the chamber = moisture equilibrium is reached), the water activity can be read directly on the display of the humimeter RH2 water activity meter
The time until the moisture balance is reached depends heavily on the material to be measured, as well as on the temperature. Hygroscopic materials such as cornflakes assimilate in a much shorter time than whole corn kernels. In this context, it is important that the samples have the same temperature as the measuring instrument or measuring chamber – high temperature differences lead to a longer conditioning time. This material-dependent conditioning time is a physical phenomenon and cannot be artificially shortened. Generally, the conditioning time lasts from 5 minutes to about an hour.
The moisture balance is achieved when the displayed reading does not change over a period of several minutes (e.g. 10 minutes, changes less than 0.002 aw).
In this video we explain how to calibrate and adjust the aw-value measuring chamber itself. For this you need the right calibration solution (certified calibration ampoules).
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