Calculations Tankvision
28 Endress+Hauser
8.1.3 Tank Shell Correction - CTSh
• The Tank Shell expands and contracts with temperature changes (compared to TCT
calibration temperature)
• Some countries require CTSh (Correction for Tank Shell temperature effects)
• For heated products the CTSh can be in excess of 0.3% TOV
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For more details see → ä 52, Chapter "CTSh".
The Tank Shell Correction is a factor which is multiplied with the TOV reduced by the
FWV.
8.1.4 Floating Roof Correction - FRC
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A tank can often have a floating roof. A floating roof is called so because it floats on the
product stored in the tank. The roof moves up or down along with product level. Since the
roof is floating on the tank, it displaces some amount of product depending on the weight of
the roof and the density of the product. This displacement in prouct level results in a
different apparent level, introducing an error into the volume calculations. The product
volume therefore needs to be corrected.
A floating roof often has supporting legs. The roof can be rested on these legs when the level
is too low or the tank is empty. This allows maintenance staff to enter below the roof for
carrying on tank maintenance. Based on the product level, the floating roof can be landed on
the legs or floating on the product. However, in a certain range of product level, the floating
roof can be pertially landed. This zone is called "critical zone". In the Tankvision system there
can be two critical zones related to the position of the floating roof legs.
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