INTRODUCTION If mutually agreeable@ automatic line sampling devices@ which meet the standards set out hereinafter@ may be used to withdraw line samples for the purpose of determining gravity@ BSW (basic sediment and water) and other characteristics required in custody transfer. The quantity of sample collected must be of sufficient size for analysis@ and its composition should be identical with the composition of the batch flowing in the line while the sample is being taken. An automatic-sampler installation necessarily includes not only the automatic sampling device which extracts the samples from the line@ but also a suitable probe@ connecting lines@ auxiliary equipment@ and a container in which the sample is collected.