Weighing is Ideal
You can choose from a wide variety of measuring methods for tank inventory control of solids or liquids. However, be advised that accurate results can greatly depend on material characteristics and environmental conditions. Non-contact distance and level measurement techniques and almost all flowmeters only provide a volume measurement. In contrast, weighing technology provides a reliable and accurate result for all conditions and for each material.
Conveying, storage and measuring liquids and solids in a tank or silo is a science. Countless publications and presentations confirm that. Some companies use large testing laboratories to determine the behavior of materials in different situations based on practical trials. Those findings are used to develop the most ideal materials-handling and storage equipment for individual materials. This will determine the appropriate measurement technology.
Accurate inventory control inside tanks and silos is important to optimize the management of expensive material. It can also be important for safe hazardous material storage and to detect even the smallest leak. Batching or out-dosing, including small quantities of material, can also require accurate inventory control to ensure product quality.
Maintaining Accuracy
Weighing technology enables inventory control for tanks or silos of up to three tons with a reproducible readability according to International Organization of Legal Metrology (OIML) guidelines of 30,000 divisions or 0.0033%. Inventory from three to several thousand tons can be taken with accuracy between 0.01 and 0.5%. These values are independent of flow behavior, temperature, density, viscosity or any other material characteristics.
A tank or silo can be calibrated by verified weights at the place of use. The calibration and adjustment also compensates for deviations due to rigid pipe connections or deflection of the tank or silo’s support structure at full load. Execute this with traceable weights and a certificate that you can be obtain by documenting the calibration values to prove performance and traceability to the standard for mass.
In Conclusion
Distance-measuring sensors and flowmeters can be useful for inventory control in tanks. In fact, those technologies have advantages over weighing for certain applications. But in many cases, weighing is superior because the technology is never in contact with the material and it directly determines the mass of the inventory when the calibration is correct. There are no restrictions with respect to the tank or silo shape or material characteristics. The maintenance and calibration over the entire lifecycle is simple. The expenses related to constructive adjustments for the installation of weighing, as well as high-quality level sensors or flowmeters are similar in most cases, but weighing is typically more accurate.
