Weighing of tank or silo, some aspects are underestimated
Some aspects of process weighing are underestimated, overestimated or simply overlooked. This article will provide you with an insight into the most important aspects for tank or silo weighing.
Which load cell capacity should I choose for weighing a tank or silo?
The total weight of the silo, filters, motors, valves, mixers and of course the contents divided by the number of load cells. If the silo is to be placed on 4 load cells, it is advisable to provide 30% overcapacity.
What is the “best possible accuracy” I can achieve?
Well, usually the load cell is not the determining factor, but whether your silo has many “fixed connections” to the environment, e.g. piping, ladders, pumps etc. And how flexible these connections are attached to your silo. This is important for weighing the tank or silo.
What misconceptions exist about load cell accuracies?
The most common “verifiable” load cells have a C3 class, which means 3.000 divisions. Many users from the process world think that a load cell with 3.000 divisions does not measure more accurately than the load cell capacity divided by 3.000. So a 3.000 kg load cell would not be able to weigh more accurately than 1 kg. This is a serious misunderstanding! The C3 indication on the load cell determines that, according to the calibration legislation, you may build a “verifiable” scale with a maximum of 3.000 divisions with this load cell. How accurately or how “small” you may weigh with a certain type of load cell is not determined from the C3 indication, but from the indication: “minimum verfication interval”, which loosely translates as the smallest verifiable part.
What is the importance of the smallest verifiable part of a load cell?
This determines for the load cell what the smallest particle is that you may display on the display of a verifiable weighing device. For the SPSX load cell this is the load cell capacity divided by 15.000. For a 30 kilogram SPSX load cell this is 2 grams.
What signal does a load cell give when weighed?
The signal that is measured on a load cell is a current. When the weight on the load cell increases, this current increases. This current is expressed in millivolts per volt. Most load cells give an output signal of 2 or 3 mv/V. The 2 or the 3 refers to the maximum millivolt signal that the load cell delivers and that happens at 100% load. The “per” volt refers to the power supply: per volt of power supply, the load cell delivers 2 or 3 mV at full load. So: if the weighing amplifier gives a power supply of 10 V, a 2 mV/V load cell delivers 20 millivolts at full load; with a power supply of 5V, this is only 10 mV.
Dexman your partner for weighing tanks or silos
We at Dexman know better than anyone that the right information is the most important thing. Because if a measurement is not correct, the solution is of no use to you. This applies not only to the solutions we offer, but also to the way in which we communicate. At Dexman, we stand for quality, service and solution orientation. In this, it is important to provide the right information, offer a good solution and be honest with each other.
Dexman is a supplier with a wide range of
load cells,
weighing platforms,
pallet scales,
crane scales,
force sensors,
torque meters,
measuring amplifiers,
pressure sensors en
displacement sensors. You can contact us for standard versions, but also for custom-made components and complete weighing solutions. The choice of the right components usually starts with extensive advice.
We are active in the following sectors: offshore, aerospace, logistics, agriculture, food and pharma. Thank you for your interest in Dexman products and services. We look forward to the opportunity to serve you.
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