Teksten forneden er maskineoversat fra den tyske originaltekst.
About Hygrometer
-
What are humidity measuring devices/hygrometers?
-
How do air humidity meters/hygrometer work?
-
Where are the humidity measuring devices/hygrometers used?
-
Calibration types of the air humidity meter/hygrometer
-
FAQ – frequently asked questions about humidity meters/hygrometers
What are humidity measuring devices/hygrometers?
Humidity meters are a group of meters used to measure the moisture content of the air or in materials. These are usually compact multi-function measuring devices, which can also measure other physical quantities such as temperature, CO2 content, absolute pressure or flow. Analogueue models are also represented in this category of measuring instruments.
The name hygrometer contains the Greek word for "damp" or "wet": "Hygros".
The indoor climate has a strong influence on the well-being of the people who are in it. The CO2 concentration is considered to be an important indicator of indoor air quality. Poor air quality with too high CO2 concentration leads to fatigue, lack of concentration and can even cause health problems. This makes the room climate a safety factor. Some of the most common values, which can also be transferred to office space, are:
| Town | Recommended temperature | Recommended humidity |
| Bedroom | 16 - 18 °C | 50–70% |
| Kitchen | 18 °C | 50–70% |
| Living room | 20 °C | 40 – 60% |
| Bathroom | 23 °C | 50–70% |
However, even in sensitive production facilities, for example in semiconductor production, or in the storage of certain products, such as foodstuffs, there are often special requirements for the quality of the air. With air humidity measuring devices or hygrometers, the quality of the room climate can be determined very quickly and reacted in time to the exceeding or falling below normal values.
How do air humidity meters/hygrometer work?
The basic principle of the measurement is that the properties of a (measuring) medium change when exposed to moisture.
One example is the hair hygrometer, where a human hair is traditionally used as a sensor. As moisture increases, the hair expands. This extension is transferred to a pointer that displays the value on a calibrated scale. In the meantime, synthetic fibers are sometimes used for this type of measurement.
Modern equipment uses the changes in electrical parameters when exposed to moisture:
Sensors (Capacitive)
Between two electrodes there is a hygroscopic layer, so to speak, as a dielectric. If the moisture content of this layer changes, the capacity between the electrodes changes. Thus, this structure works like an electric capacitor, but its value can be changed. The capacity serves as the measuring equivalent for the humidity. Non-conductors with hygroscopic properties such as plastic polymers or ceramic materials are used as dielectric materials.
Impedance sensors
These sensors use a hygroscopic layer between two DC electrodes. The electrical (resistive) resistance changes as moisture is absorbed or absorbed. This value is evaluated as a humidity equivalent.
Mixed form impedance/capacitive
If alternating current is used, a mixed form is created, because these sensors measure both the change in the resistance of a weak conducting hygroscopic material as well as its capacitive properties.
The measurement result is output on energy-saving digital displays. Some devices emit warning signals when critical values are exceeded or respond with a tone sequence that follows the change in the measured value.
There are air humidity measuring devices/hygrometer with integrated and offset measuring probes, which are connected to the hygrometer via system plug.
The moisture measuring devices for materials have differently designed measuring probes, usually as double metal tips, with which the moisture value is determined by means of the flowing current by placing on or in the medium.
Many of the devices at Conrad can be used as data loggers, in order to mark out measurement series and evaluate them afterwards on the PC. Some models have an SD card slot for recording measurement results on a corresponding card.
Where are the humidity measuring devices/hygrometers used?
- Room climate measurement
- Regulate and test air-conditioning systems
- Measurement of the pressure dew point in compressed air systems
- Assessment of indoor air quality using the IAQ probe (IAQ means indoor air quality)
- Measurement of moisture in building materials or components of buildings
Calibration types of the air humidity meter/hygrometer
Calibration according to ISO
The quality-relevant characteristics of the device are measured with calibrated measuring instruments according to DIN EN ISO 9001:2015.
Calibration according to DAkkS
The calibration by means of a certificate from an accredited calibration laboratory guarantees the traceability of the measurement results and thus their international comparability. Deutsche Accreditation Body GmbH (DAkkS) is the national accreditation body for this purpose.
Calibration according to factory standard
The device is calibrated according to the manufacturer's own specifications and is not presented to any calibration point.
FAQ – frequently asked questions about humidity meters/hygrometers
What must be observed when handling air humidity measuring devices/hygrometers?
- The measuring device may only be used for object and intended purpose and within the parameters specified in the technical data.
- Do not measure on or near live parts with the meters and probes.
- Never store measuring devices/measuring cells together with solvents or use desiccant during storage.
- Observe the manufacturer's instructions on product safety and circumstances that invalidate the warranty claims. Therefore, the measuring device may only be opened if this is expressly provided for maintenance or maintenance purposes in the documentation.
- Handles and feeders should not be exposed to temperatures above 70 degrees Celsius unless they are expressly approved for higher temperatures. Temperature specifications on probes or probes refer only to the measuring range of the sensors.
- You should use original spare parts for maintenance and repair work
- A measuring device must always be disposed of properly after use.
- Defective batteries or empty batteries must be delivered to the designated collection points.
Where must the humidity measuring devices/hygrometer not be used?
- In hazardous areas
- For diagnostic measurements in the medical field
How long does a humidity meter/hygrometer last?
The devices in the Conrad professional shop are subject to the statutory two-year warranty. With proper use, storage and maintenance, a much longer service life is possible. Regular testing and the timely replacement of the batteries or rechargeable batteries are particularly important.