IN ORDER TO COMPLETE THE HYDROCARBON CUSTODY TRANSFER TRANSACTION, one needs to determine the quality of the hydrocarbons in addition to the volume. Samples of petroleum and petroleum products are examined by various methods of test for the determination of physical and chemical characteristics. The test results are used for custody transfer, quality, and price determinations. Sampling is also required for inventory quality validation at many points in addition to the custody transfer points. The same care in sampling is required when sampling for regulatory compliance, process control, or internal quality validations. The samples must be representative of the petroleum or petroleum products in question. We will cover the procedures and equipment necessary to obtain a representative sample on which quantitative and qualitative analyses can be performed in Section I: Manual Sampling, and Section II: Automatic Sampling.