In the pharmaceutical, building materials and food industries, on vessels and silos, on platforms and dosing systems, right around kitchen and bathroom scales ? Focused is measured everywhere. In industry, it becomes particularly interesting in terms of the particular level in vessels. There are many possibilities for weight measurement or weighing. The filling level can be determined optically, hydrostatically, by ultrasound, microwaves and radar, mechanically, capacitively, by heat dissipation, by displacement and resistance or, what this short article is about, gravimetrically.
The term gravimetric is composed of the Latin ?gravitas? for ?gravity? and the Greek ??? ??????? for ?measure?. In gravimetric measurement, therefore, the heaviness of the mass is combined with weight force to form a meaningful value and thus the level is determined by weighing vessels (the filling level results from the density of the medium and the geometry of the vessel). This makes gravimetric level measurement a part of weighing technology.
Gravimetric level measurement is specially suitable when uneven distribution can occur within the vessels.
Gravimetric level measurement: Advantages
This type of weighing has several advantages. Possibly the greatest advantage is that the force transducers used for gravimetric level measurement are located beyond your vessel. Thus, they don’t come into contact with the product. Nor is it necessary to open or modify the vessels. Contamination can thus be eliminated. Cleaning can be easier. Furthermore, very precise measurement can be done ? 0.02 % of the rated load is not uncommon regarding relative linearity error. This makes dosing possible when, for example, food is filled into bags ? and of course the packaging must contain the amount specified.
Another advantage is that the product will not influence the measurement. The level could be determined gravimetrically for all contents ? solids, liquids, viscous substances, foaming substances ? even toxic or aggressive contents can be viewed as. Furthermore, Uncaring isn’t falsified even though voids or uneven contents distribution occur inside the silo or tank, as the entire contents are weighed.
Suitable mounting modules not merely ensure that the weight force is properly led in to the force transducers, in addition they make installation super easy. The module and force transducer have a minimal height and a small installation volume. However, it usually is problematic if the vessels already are permanently installed and will only be positioned on modules with significant amounts of effort. Then it is probably advisable to bolt strain transducers to the supports. The strain transducers determine the compression of the supports caused by the weight of the contents. They thus be able to weigh immovable vessels gravimetrically.
Gravimetric level measurement: Disadvantages
The disadvantages of gravimetric level measurement vary in significance based on the application. Results are mainly distorted when force shunts can’t be prevented. Ideally, the vessel should be mechanically decoupled. In practice, however, it can always happen that, for example, struts are essential. Then it depends on what great their supporting effect is. Similar problems may appear if the measurement is influenced by way of a high bearing weight. The lower the weight of the vessel when compared to product, the more accurate the gravimetric measurement. Finally, free-standing outdoor vessels can be suffering from natural factors. For instance, if wind pushes or snow leads to a significant increase in weight.
Typical force transducers for the weighing of vessels
Single point load cells are classically useful for scales. These not merely have a low price and high accuracy, however the weight is also determined reliably, no matter where it is placed on the platform. For optimal force introduction, bending or shear beams with the corresponding weighing modules are often installed under tanks, silos or vessels that stand on supports. To look for the rated load of the force transducers, divide the total weight of the vessel by the number of supports. If the rated load exceeds 10 t, you’ll be able to switch to compression force transducers, the utmost capacity which reaches up to 300 t. With four supports, vessels of up to 1,200 t could be weighed with the best accuracy. Alternatively, vessels could be suspended from S-type force transducers or fitted with strain transducers.
Note
Obsession can be measured in many various ways. Whether gravimetric as described, or with a submersible pressure sensor, float switch or pressure sensor ? WIKA has the right sensor for each application. Would you like to buy the products? Inside our WIKA online-shop you will discover a few of our standard designs. Should you have any questions, your contact will gladly assist you to.
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