Research On The Measurement And Correction For Tank's Volume

Liquid tank volume calculation is one of the most popular measures in the international trade about the liquid cargo, such as oil, chemical, and so on. Now the liquid cargo volume measuring precision is 0.2% which is far drop behind the market requirement. Suppliers and carriers usually disputed about the quantity of the goods during the handover and takeover. So improving the precision of the measure and decreasing the measuring error is a problem needed to be solved quickly.There are two methods to calculate the volume of liquid cargo, one is volume comparing method and the other is mix measuring method. This paper carries out particular analysis and comparing about these measuring methods and software, then select the mix measuring method to study the problem of volume measuring and correcting, and develops a new measuring software to improve the calculation precision and speed. At first, the author consults all kinds of hull forms' calculating and fitting methods, makes a compare among the methods, chooses the B spline fitting methods to work out this job. Then author gets the coordinate of the special point in the liquid tank, calculates the cross section area by integral, on the basis of Matlab fitting the offset in the cross section. Finally, by the complex Simpson method along the direction of the portrait and the vertical, we can calculate the molded capacity in upright top up, take out member volume, and makes a sheet of the storage capacity in this condition.Capacity correction is an important step to improve the precision, mainly contains the heeling correction, trimming correction, and member correction. Heeling correction which uses the clinometer to indicate the incline direction and degree, calculates the correction value of molded capacity by the method of geometrical, performs the correction in the condition of upright top up. Trimming correction is a way of using the area integral or Simpson to calculate the volume correction value. Member correction collects the data information of every member in the tank, such as original coordinate, ending coordinate,member type , number ,and so on, then software calculates the unite area of the member, according to the real liquid lever height ,and gets the volume of member need to be cut. At last a sheet of the volume correction will be made, to be used as a reference of the zero keel capacity sheet, and we can get the exactly capacity been corrected, that is the precision liquid cargo capacity.