My vendor filled liquid oxygen in our 11000 liter capacity tank. He filled from 1400 MMWC up to 3200 MMWC. I followed the provided conversion table and found that we had been supplied 1800 MMWC liquid which is going to yield 2815 cubic meter. On the other hand, the vendor claims that he supplied as follows:- 5236 cub mtr(3200 MMWC)-2124 cub mtr(1400MMWC) = 3112 cub mtr. I fear that he wants to charge 297 cubic meters extra. He claims that my method was wrong and his was right. He says that this disparity is because of the conical shape of the base of the flask. I will be thankful if somebody can explain me the truth.