GB1469563A - Method of determining the internal shape of an approximately spherical tank for the computation of the volume of liquid held in the tank - Google Patents

Abstract

1469563 Measuring volume BLOMS OPPMALING AS 9 Aug 1974 35256/74 Heading G1X To determine the internal shape of an approximately spheral tank, e.g. of a ship-borne liquified natural gas tank, for the computation of the volume of liquid held in the tank, a set of measuring points, e.g. platforms P 1 -P 5 , are established in the tank and a co-ordinate system, X, Y, Z, is established by reference to the measuring points, the origin OT of the system preferably being at or below the lowest point of the tank, a plurality of markers SI-SN are placed on the internal surface of the tank to define reference points, and the positions of the reference points are measured from the measuring points P 1 -P 5 , the reference points are plotted in their projected positions on a horizontal great circle plane, Fig. 2, together with a computed centre point C of the sphere, the projections of horizontal small circles ZM, ZM + 1 etc and traces of vertical planes SNP through C are drawn on the plot, stereoscopic photographs are taken of the internal surface of the tank, and the photographs are observed in a photogrammetric apparatus using the plot to guide the observation system of the apparatus to the approximate positions of further points at the intersections of the vertical planes SNP with the horizontal great and small circles, and the co-ordinates of the reference points and the further points as measured by the photogrammetric apparatus are transferred by way of an interface unit to a computer for computation of the volumes of liquid held by the tank for different levels of liquid in the tank and for different trim values of the ship.