As an international active and renowned manufacturer, supplier and service provider for devices, systems and systems for the contactless detection of various process parameters (e.g. density and humidity) mainly of bulk materials (e.g. coal and potassium salt) we want to offer our customers the most effective solutions for their processes.
The possible technical solutions are ultimately defined by analyzing the customer processes and the operating conditions on site. You can find out how these can look in this section.
The term "moisture" describes the degree of water content in a material, a substance or a gas; when the value is too high, it is called wetness.
It is not a question of the proportion of water bound in the crystalline structure, but of that between the cells. Because this water can have a detrimental effect on the material, the process in which it is bound and thus on its lifespan, reliability or even safety.
We speak about water content primarily in physics and materials science, whereby moisture or moisture can also refer to the proportion of other liquids.
We know moisture measurement from the most varied areas of everyday life (e.g. building moisture, soil moisture, etc.), but it occupies a special place in industrial measurement technology.
Especially in mining, the moisture is determined in order to deduce the quality of the coal being mined, just like when determining the "ash content".
In general, the range of methods for moisture determination is very extensive, although they are often very specifically tailored to defined applications and could not be used anywhere else:
● hygrometer
● Time domain refletometry
● Calcium carbide process
● microwave
● capacitive
● NIR
● gravimetric (Darr method)
● Karl Fischer titration
● conductivity
● tensiometry
● radiometry
In mining, the water content is mainly determined using NIR, microwaves or radiometric.
belong to the electromagnetic waves that are able to penetrate matter.
This applies as long as it is not electrically conductive. In materials composed of dipole molecules, e.g. Water, the molecules are vibrated by the microwaves. Here they lose their energy.
The loss depends on the amount of water they penetrate.
In solid moisture measurement, weakly bound water molecules are made to vibrate by electromagnetic waves, because free water absorbs electromagnetic energy of certain wavelengths (so-called absorption band).
A light beam generated is partly absorbed and partly reflected on the moist surface of the opaque material.
The best measurement condition is found when the measurement medium surrounds the source and the detector.
Depending on the humidity, a spherical volume is formed in which the water content determines the measurement signal.
Since the highest concentration of slow neutrons is near the source, the detector must also be placed here.
There are currently predominantly online moisture meters on the market with the following principles:
● Online near infrared moisture meter,
● Online moisture meter for microwaves,
● Online neutron moisture meter
● as well as RF and capacitive types.
Systems with neutrons are radioactive, safety-relevant and are therefore rarely seen, but only this principle can be used to measure the moisture of large coke lumps;
Nowadays, the market is mainly governed by two principles: infrared and microwave.
Infrared is mainly used for powdery, very fine-grained or plate-shaped products (such as paper and tobacco), since moisture measuring devices based on this measuring principle are suitable for products with the same moisture content inside and outside.
Devices and/or systems working with microwaves can not only measure in such applications, but the moisture of products with particle sizes over 3mm diameter can only be measured with microwaves.
If the moisture inside and on the surface is different, IR is the wrong choice, because with IR only the surface can be measured and the error would be very large, so you have to be careful with products with inconsistent moisture inside and on the surface and more like a moisture meter select according to the microwave principle.
Our staff would be happy to help you and take care of your inquiries and orders.
You can get help and advice on the selection of the measuring system that best suits your application
from our experts in process measurement technology.
