The humimeter RH2 in its water activity version (art. no. 12005 aw) is a laboratory water activity meter with a data logger for quality control, shelf life and product safety in food and other materials. It measures water activity from 0 to 1 with a resolution of 0.001 aw, and alongside it the relative and absolute humidity of the air above the sample, temperature, dew point and equilibrium moisture content. The water activity measurement is in line with ISO 18787:2017, the standard for determining water activity in food. It replaced the withdrawn EN ISO 21807 and explicitly covers measurement with a capacitive sensor, as used in the RH2.
Typical products are butter, fruit mixes, spices, granulates, mushrooms, xylitol, flour, biscuits, sausages and cured meats, and PVC granulate. The measurement makes sense wherever shelf life depends on the water available to micro-organisms rather than on the water content itself.
The meter itself is the basic device: water activity is measured with the aw measuring chamber 13700 or the aw measuring cell 14500, ordered together with the meter. Without one of them the RH2 cannot measure aw.
Both sensors have the same range and the same accuracy. They differ in sample volume: the chamber works with 186 and 245 ml jars, so it suits larger samples and pieces of product, while the cell works with 25 ml inserts and is meant for very small quantities of material.
| Feature | Chamber 13700 | Cell 14500 |
|---|---|---|
| Sample container | screw-top jars 186 ml and 245 ml | plastic (PP) inserts 25 ml |
| Reaching equilibrium | a fan forces air circulation in the chamber | the small dead volume above the sample shortens the equalisation time |
| Water activity | 0 to 1, resolution 0.001 | as chamber |
| Calibration (25 °C) | ±0.01 aw from 0.10 to 0.80, ±0.04 aw from 0.00 to 0.10 and from 0.80 to 0.98 | as chamber |
| Sensor operating temperature | 0 to +50 °C, calibration ±0.5 °C (25 °C) | as chamber |
| Dimensions | ø 85 × 102 mm (186 ml), ø 85 × 111 mm (245 ml) | ø 88 × 86 mm |
| Weight | 542 g (186 ml), 556 g (245 ml) | 1.2 kg |
| Supplied with | 2 jars 186 ml, 2 jars 245 ml, 4 twist-off lids, ampoules 10005, certificate 10403, case 13624 | 8 PP inserts 25 ml, ampoules 10005, certificate 10403, case 13624 |
| Replacement sensor | 14880 - for chambers with serial numbers 20000 to 30000 | 14937 - for all cells |
Your benefits
|
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| Article no. | 12005 aw (basic device) |
| Water activity | 0 to 1, resolution 0.001; calibration 0.00 to 0.98 |
| Water activity accuracy (25 °C) | ±0.01 aw from 0.10 to 0.80; ±0.04 aw from 0.00 to 0.10 and from 0.80 to 0.98 |
| Relative humidity | 0 to 100 % RH, resolution 0.1 % RH |
| Temperature | aw sensors 0 to +50 °C, resolution 0.1 °C, calibration ±0.5 °C (25 °C) |
| Dew point | -55 to +60 °C, resolution 0.1 °C |
| Absolute humidity | 0 to 130 g/m³, resolution 0.1 g/m³ |
| Equilibrium moisture content of wood | 2 to 30 %, resolution 0.1 % |
| Equilibrium moisture content of POM granulate | 0 to 2 %, resolution 0.01 % |
| Memory | 10,000 readings with measuring point description; manual and automatic logging, hold and online functions |
| Display | backlit dot matrix 128 × 64 |
| Operating temperature | meter -10 to +60 °C, aw sensors 0 to +50 °C |
| Storage temperature | -20 to +60 °C |
| Protection class | IP 40 |
| Dimensions of basic device | 145 × 75 × 30 mm |
| Weight of basic device | 210 g including batteries |
| Power supply | 4 × 1.5 V AA alkaline batteries; current consumption 60 mA with backlight |
| Menu languages | English, German, Italian, French, Spanish, Portuguese, Czech, Polish, Russian, International |
The humimeter RH2 is supplied with a rubber protective cover and batteries, together with the selected water activity sensor and its accessories:
The USB module with LogMemorizer software is not included. It is ordered separately: 12278 or 14957.
A damaged sensor is replaced on site: the replacement sensor slides straight onto the sensor head, without sending the device to the manufacturer.
Measuring methods selectable in the menu:
In both automatic methods the meter ends the measurement itself once the reading is stable.
The device is not suitable for juices, syrups, acidic products such as vinegar, or food and beverages containing alcohol. Acids and alcohol can damage the sensor or change its calibration. The RH2 measures water activity, not the water content in per cent.
Calibration is checked with certified calibration ampoules. The set 10005 (35, 50 and 80 % RH) is included with the chamber and the cell. Check the calibration in the approximate range of use: for measurements from 0.2 to 0.5 aw, use the 35 and 50 % RH ampoules. The meter, chamber or cell and ampoules should be at 20 to 26 °C, ideally 23 °C. The sensor equalises with the ampoule in 3 to 20 hours at 35 and 50 % RH, and in 6 to 20 hours at 80 % RH. If the reading differs from the ampoule value by more than 1.5 % RH, adjustment is recommended. It is carried out by Schaller Messtechnik or by the user following the separate humimeter RHx calibration and adjustment manual.
A calibration certificate with PCA accreditation from a Polish laboratory can be ordered instead of, or together with, the factory calibration certificate 10403.
The RH2 basic device also accepts probes for air humidity and bulk materials and an infrared temperature sensor. These are described on the humimeter RH2 with exchangeable sensors page.
Interested in the humimeter RH2 water activity meter? Get in touch for more information, a quotation or individual advice.
Polski