L-K Log: March 2018 
Centrifugation: Still Relevant, Always Superior
Water is an essential component in so many aspects of life, including in our bodies and on our planet. But water in crude oil and petroleum products is problematic – and can be costly if included erroneously in the “net dry oil” calculation. Assessing the amount of basic sediment and water content (BS&W) in crude samples is critical, yet accurate analysis is difficult.
Currently, the oil Industry uses three different static methods to determine water content in oil: Karl Fischer titration, a distillation method called the Dean and Stark Test, and the oldest and most widely used method, the centrifuge test.
Although Coulometric Karl Fischer is very accurate (at .5% water, it is four times more accurate than centrifugation and two times more accurate than distillation), it’s not practical for the field, affecting use in custody transfers and sample analysis. The Dean and Stark distillation test is used to settle disputes when parties can’t agree on centrifuge results, but is time consuming and can only be conducted in a laboratory setting. Additionally, neither of these methods can determine sediment content. The centrifuge, the tried and true method dating back to the separation of cream from milk in the 15th century, stands alone for determining BS&W in crude oil samples in the field and in the laboratory.
The Original Melton Centrifuge
Manufactured in 1957
In this method, L-K Industries set the bar. The Melton Centrifuge became the hallmark of the company and set the oil testing industry standard for centrifugation. In 1962, ASTM standards were released based on the Melton Centrifuge, and to this day it stands as the single invention that changed the course of the oil testing industry. William L. Melton, in his United States Patent application, described the device as an “invention [that] relates to a centrifugal machine for testing oil that must be heated to a predetermined temperature, and more particularly to a machine for testing crude oil in the oil fields…”
Today’s L-K centrifuges exceed API/ASTM Standard Requirements and customer expectations. Equal volumes of oil and solvent are placed in a graduated tube. After centrifugation, the volume of the higher gravity water and the sediment layer at the bottom of the tube is recorded. In the upcoming Benchmark Platinum, ultra high-speed capabilities of 2700-3000 rpm will further improve separation of elements and yield more accurate results. Additionally, with its Class I, Division 2 status, refined features, and interactive display, centrifugation will be the field and laboratory method of choice in the petroleum industry.
The Benchmark Platinum Centrifuge is the third edition of the Benchmark series. It will feature an all-in-one interactive screen, ultra-high speed for better oil separation, and a redesigned lid for easier bowl access. L-K is excited to bring the Platinum to customers in 2018!
L-K exhibited at the API’s Spring Committee on Petroleum Measurement Standards.
