BS&W is determined using ASTM Standard D96, D4007 or the API Document "Sediment and Water", Chapter 10, Section 2, 'Determination of Water and Sediment in Crude Oil by the Centrifuge Method".
Other methods available for water in crude oil are ASTM D4377, D4928, IP386.
http://www.astm.org/Standards/D4928.htmhttp://www.astm.org/Standards/D4007.htmHere you can see the most common list of crude oil laboratory analyses (crude assay), required for transfer and downstream processing:
http://www.intertek-cb.com/petrotesting/cr...aytesting.shtmlBS&W are more important as economic parameter - they actually show to the customer the amount of crude feedstock which should be accounted into "losses" prior to any processing.