Mobile moisture measurement with wireless technology

Quality controls have always played a significant role in the manufacture of concrete products of any kind: whether for civil engineering, building construction, and garden and landscape construction. The company Franz Ludwig has now developed a new testing device, the FL-Mobi Mic Profi- Check, which exactly determines a product’s moisture and temperature. The testing device can be used in several places during mixing and batching processes.

The exact percentage of moisture values and thus the net weight of individual bulk goods can be rapidly and exactly determined upon arrival of the raw materials. This unit, moreover, efficiently supports stationary bulk goods probes. In addition, it delivers valuable measuring results on the water-cement ratio and the media temperature during production of no-slump or plastic concretes in the plant, in the laboratory, or at the construction site.

Time-tested microwave measuring system

The mechanical buildup of the mobile moisture measuring unit is clear and functional for use in practice. The measuring head is made of high-quality stainless steel and designed for easy insertion and/or penetration into the medium being measured; the moisture measuring probe, provided with a robust measuring ceramic for protection, is integrated in the measuring head.

The measuring head is connected to the evaluation and transmission electronics via a 250 mm long V2A connecting tube. The robust die-cast housing, designed of IP65, protects it from mechanical wear. The adjustable carrying handle is also attached to the housing and facilitates simple insertion and replacement of the measuring unit.

The measuring technology is based on the time-tested microwave measuring system that operates in the frequency range of 433 MHz. It makes use of the dielectric constant  of water, which has a relative permittivity of εr 80. This parameter indicates the propagation of electric fields in the materials. The high relative permittivity of water predestines the microwave measuring system for determining the moisture of bulk goods. Different media and changing ambient temperatures have no influence on the precision of the microwave measuring method described herein.

In developing the new system, priority was placed on the basic requirements, such as, for example, the high reproducibility of the measured values, speed, ease of operation, universal use, a good price/performance ratio, wireless measuring technology, and a compact and robust buildup.

Results within a few seconds

In developing the unit, special emphasis was placed on ease of operation. Towards this end, the FL-Moby Mic Profit-Check was fitted with wireless technology by means of which it is possible to communicate with a compatible receiving device via purpose-designed software. Here, intuitive operation was a priority. Many standard calibration curves for bulk goods and concretes, for example, are already contained in a list of favorites that can be simply selected and assigned. The list of favorites can be infinitely updated by the customers.

All measuring tasks are saved and can be transmitted to an Excel file for subsequent activation. The actual measuring period can be adjusted, but is in general only 6 s. The user devices can be run on Windows-based standard notebooks or tablets; the distance to the device can be several meters. There is no control panel on the housings. This was done on purpose so as to protect the housing from dirt and/or damage during measurements.

Runtime up to 48 h

The rechargeable battery integrated in the wireless technology used enables a continuous runtime of up to 48 h. The battery can be easily charged by plugging it into a power outlet or a cigarette lighter in the car, using the charging cable that is part of the delivery scope.

The FL-Mobi Mic Profi-Check unit, based on statements by users, was able to demonstrate its practical use and handling comfort after a relatively short period of time. The manufacturer reports that the product is establishing itself very well both on the domestic and international market.

The system supports the personnel right on location in the plant and enables them to carry out just-in time quality controls so that they can quickly and effectively react to changes in the production process.


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