Tier III Sulfur in Gasoline Analysis

Under the law, the U.S. EPA is responsible for reducing or eliminating pollution. One of the central issues has been improvements in the quality of fuel burned in various types of vehicles. Recently, the EPA has begun promulgating the regulatory requirements for Tier III gasoline. The requirements affect all parties in the gasoline supply chain and must be understood by many parties.

The heart of the requirement is the implementation in the incorporation of PBMS testing. This was originally developed for the implementation of the 2006 ULSD testing requirements. The success of this program caused it to be incorporated and expanded for Tier III Gasoline. The key feature of the program is a simple way for each site to verify their ability to comply with the requirements upon the commissioning of the instrument and throughout its lifetime.

The initial certification begins with verification of the fact that the minimum requirements for the testing are being met. The initial test is a verification of the accuracy. This is composed of the analysis of two concentrations of samples a total of ten times. The COA of the results is determined and compared to a predetermined minimum acceptable value. This sort of data is kept at the laboratory for examination by the EPA auditor.

If the accuracy test has been successfully completed, then the precision test is begun. This is the testing of a particular set of samples over the period of 20 days at the site. This test is essentially designed to access the repeatability of the instrument. The 20 pieces of data are averaged together and the standard deviation computed. This value is again compared to a minimally acceptable number. Again, this baseline data is retained the laboratory for examination by the EPA auditor.

The new feature for Tier III gasoline is mandatory tracking of SQL data to assure the on-going acceptability of the data being generated. This will take the form of accuracy and precision SQC charts. While the exact details of the charts and their criteria have not been defined, it is expected to be very typical of the good laboratory procedures which are in use today in well-run laboratories. The precision data will again be based upon the use of standards, which are measured in periodic routine.

The same sort of analysis will also be used to access the precision of the data being generated. This consists of making the measurement and determining the trending in the data if any exists. These requirements will be significantly harder to define simply due to the statistics. Again the EPA has not yet defined the 'Run Rule Strategy', but it is expected to be out any day now. The charting will again be typical for SQC graphs.

With all of this testing begin required, it immediately suggests the need for reference materials for analysis. Fortunately, a number of the companies that provide petroleum standards have anticipated this need. They have standards to meet all of these requirements prepared as a kit to purchase. This will save considerable time as you launch your testing program. It will also provide you with background material to make your job easier.