When it leaves the refinery, ultra low sulfur diesel (ULSD) should be under the required 15 parts per million limit. But on the way to the pump it could pick up a few more parts. Apparently the tankers hauling ULSD also transport jet fuel and off-road diesel. By one estimate, every change of hands could add 2 ppm of sulfur. Not every fleet company takes the time to flush the tanks and delivery hoses when needed. Additional labor and logistical costs are hindering efforts to sort out the schedules and procedures. The key, according to one analyst, is to load ULSD behind other low-sulfur products like ethanol and biodiesel, then segregate other high-sulfur products. Getting uncontaminated ULSD diesel into your tank is critical as the modern emissions use high efficiency catalytic exhaust systems that can be contaminated by sulfur. What's making it into your tank?
[Source: Today's Trucking Online]