ISO 12917-2 pdf download – Petroleum and liquid petroleum products —Calibration of horizontal cylindrical tanks — Part 2: lnternal electro-optical distance-ranging method.
A minimum of 16 target points per course wi tanks of diameter less than 3m, and a minimum of 24 target points per course in tanks of diameter 3 m or greater, shall be sighted. The uncertainty of cabbration will be reduced if the number of target points is greater than the minimum specified.
8.4 Heads
8.4.1 FIat end, elliptical, spherical head, conical head
A minimum of 50 target points, randomly but evenly distributed over the surface, shall be sighted. The uncertainty
of the calthration will be reduced If a greater number of target points Is used.
8.4.2 Knuckledls bed end (head)
A minimum of 16 target points, randomly but evenly distributed over the surface, shall be sighted. The uncertainty of the calibration will be reduced If a greater number of target points is used.
9 Procedure for calibration
9.1 Measure and record the horizontal angle, the vertical angle and the slope distance to each reference target point. Two successive readings, at each point, shall be taken and they shall agree within the tolerance given in clause 10. Compute and record the average angles and distance to each point.
9.2 Measure the horizontal and vertical angles and the slope chstance to each target point on a surface. See Figure 2.
9.3 If more than one measurement station is required, move the instrument from station to station, taking sufficient measurements at each station to ensure a proper traverse.
9.4 After all measurements from one measurement station are completed, repeat the measurements to the reference target points.
9.5 If the repeated horizontal and vertical angles and slope distances to each reference target point do not agree with the measurements taken in 9.1. within the tolerances given in clause 10. determine the reasons for such disagreement, eliminate the cause and repeat the calibraton procedure.
9.6 Commence measurements at one head and prowess through the tank to the other head,
9.7 Carry out all measurements without loterruption.
10 Tolerances of reference target points
10.1 Distance verification
From each measurement station, the slope distance to each reference target point at the beginning and end of the calibration shall be within ± 2 mm,
A.1 Set up a stadia of 2 m ± 1 mm (this can be undertaken in the laboratory).
A.2 The stadia may be temperature compensated to maintain a distance of 2 m automatically by externalcompensation or may be compensated manually.
A.3Mount the stadia on a floor or in a tank as indicated in Figure A.1 and level the stadia.A.4Mount the tripod with EODR, as illustrated in Figure A.1.
A.5 For a given distance, D, establish coordinates of target points A and B on the reference bar.
A.6 Compute the distance AB from EODR instruments.
A.7 The maximum variation between the value of AB computed in A.6 and 2 m shall be ± 3 mm.
A.8 Increase the distance D, remeasure the angles to the fixed points A and B on the stadia.Compute thedistance AB using the remeasured angles. Continue this procedure until the variation between the computed valueof AB and the standard length of the stadia exceeds ± 3 mm.Note the smaller angle,of the two measured, andrecord it as the limiting angle of incidence.
ISO 12917-2 pdf download – Petroleum and liquid petroleum products —Calibration of horizontal cylindrical tanks — Part 2: lnternal electro-optical distance-ranging method
