1. The sampling from oil drum shall be started from the most polluted oil drum bottom, when necessary, the samples shall be taken from the upper part of the oil drum, if it is suspected most of oil in the oil drum has uneven phenomenon, the samples shall be taken again. If it is suspected that pollutants exist, then samples shall be taken from each oil drum one by one, and the brand logo shall be checked to each oil drum. During filtering, the appearance inspection shall be made to each oil drum.
2. Before opening the oil drum, clean the drum cover with clean cotton yarn or cloth, then use clean and dry the sample tube for sampling.
3. During sampling from inside of the whole batch of oil drums, the numbers of the oil drum to be sampled shall be enough to represent the oil quality of the batch of oil drums, the specific provisions  for sampling are as follows:
(1) When there is only one oil drum,  the sample can be taken from the oil drum.
(2) When there is only a batch of oil drums of 1 to 5 oil drums, the sample can be taken from 2 oil drums.
(3) When there is only a batch of oil drums of 6 to 20 oil drums, the sample can be taken from 3 oil drums.
(4) When there is only a batch of oil drums of 21 to 50 oil drums, the sample can be taken from 4 oil drums.
(5) When there is only a batch of oil drums of 51 to 100 oil drums, the sample can be taken from 7 oil drums.
(6) When there is only a batch of oil drums of 101 to 200 oil drums, the sample can be taken from 10 oil drums.
(7) When there is only a batch of oil drums of 201 to 400 oil drums, the sample can be taken from 15 oil drums.
(8) When there is only a batch of oil drums of 101 to 200 oil drums, the sample can be taken from 20 oil drums.