Research On Volume Measurement Correction Of Inclining Tank With Capacity Comparison Method

Tank volume measurement calibration is the main basis of ship loadcapacity calculation. The prescriptive measurement uncertainty accordingto the national measurement standard is no more than0.3%. However thestandard has become increasingly lagging behind the measurementaccuracy requirements of the market. While the ship is floating on evenkeel, capacity comparison method is more accurate than geometricmeasurement method, but the measuring efficiency of capacitycomparison method is relatively low. And the premise of high precision isthat the ship is floating on even keel, but in fact ships are often in aninclined state. In order to make capacity comparison method play itsadvantage, the improvement and correction method are studied in thisthesis based on the analysis of capacity calculation methods at home andabroad.In order to improve the measurement efficiency of capacitycomparison method, this paper presents an improved capacity comparisonmethod. Improved capacity comparison method does not need to measure the liquid level in the tank after every water injection. Instead the waterareas at different liquid levels are calculated through the volumedifference between two water injections, then through spline interpolationand numerical integration the tank volume curve are calculated.In order to correct the volume deviation, two different conditions areconsidered which are knowing and not knowing the theoretical offset ofthe measured tank. In the condition of knowing the theoretical offset, it isassumed that the theoretical tank and the true tank has the samecorrection ratio, then the true tank volume deviation is corrected after thetheoretical tank correction are finished. In the condition of not knowingthe theoretical offset of the tank, tanks are divided into three types:regular tank, half regular tank and irregular tank. Different amount oftank breadths are measured, then the tank shapes are reversed outcombined with the tank volume curve, after this the correction can bedone.In this paper, the corresponding example of calculation shows thatthe improved capacity comparison method and correction method canmeet the measurement uncertainty requirements of the nationalmeasurement standard, it means that the low efficiency and correctionproblem are solved, this has a very important practical significance forthe volume measurement of inclined tanks with capacity comparisonmethod.