In the pharmaceutical, building materials and food industries, on vessels and silos, on platforms and dosing systems, right up to kitchen and bathroom scales ? weight is measured everywhere. In industry, it becomes particularly interesting in terms of the particular level in vessels. There are several possibilities for weight measurement or weighing. The filling level could be determined optically, hydrostatically, by ultrasound, microwaves and radar, mechanically, capacitively, by heat dissipation, by displacement and resistance or, what this article is about, gravimetrically.
The term gravimetric comprises the Latin ?gravitas? for ?gravity? and the Greek ??? ??????? for ?measure?. In gravimetric measurement, therefore, the heaviness of the mass is combined with the weight force to create a meaningful value and therefore the level depends upon 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.
Strongly Suggest is particularly 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 touch the product. Neither is it necessary to open or modify the vessels. Contamination can thus be eliminated. Pay Zero can be much easier. Furthermore, very precise measurement can be done ? 0.02 % of the rated load is not uncommon with regard to relative linearity error. This makes dosing possible when, for example, food is filled into bags ? not to mention the packaging must contain the amount specified.
Another advantage is that the merchandise will not influence the measurement. The level can be determined gravimetrically for all contents ? solids, liquids, viscous substances, foaming substances ? even toxic or aggressive contents can be viewed as. Furthermore, the measurement is not falsified even if voids or uneven contents distribution occur inside the silo or tank, because the entire contents are weighed.
Suitable mounting modules not only make sure that the weight force is properly led into the force transducers, in addition they make installation super easy. The module and force transducer have a low height and a little installation volume. However, it can be problematic if the vessels already are permanently installed and will only be positioned on modules with significant amounts of effort. Then it really is probably advisable to bolt strain transducers to the supports. Any risk of 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 depending on the application. Email address details are mainly distorted when force shunts cannot be prevented. Ideally, the vessel should be mechanically decoupled. Used, however, it could always happen that, for example, struts are absolutely necessary. Then it depends on how great their supporting effect is. Similar problems may appear if the measurement is influenced by a high bearing weight. The low the weight of the vessel compared to the product, the more accurate the gravimetric measurement. Finally, free-standing outdoor vessels can be affected by natural factors. For instance, if wind pushes or snow results in 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 can be 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 determine the rated load of these force transducers, divide the total weight of the vessel by the number of supports. If the rated load exceeds 10 t, it is possible to switch to compression force transducers, the maximum 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
Uncensored can be measured in many different ways. Whether gravimetric as described, or with a submersible pressure sensor, float switch or pressure sensor ? WIKA has the right sensor for every application. Do you want to buy the products? Inside our WIKA online-shop you will discover some of our standard designs. For those who have any questions, your contact will gladly assist you to.
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