Ultra Low Sulfur Kerosene
Ultra Low Sulfur Kerosene (ULSK) is a light petroleum fraction, lighter than diesel. It is similar to kerosene, except that the sulfur content is at or below 15 ppm (0.0015 wt %). In its neat form it is colorless with a diesel odor. It typically has an api gravity in the 41º - 46º range. It possesses very favorable cold flow properties. Therefore many times it is blended into diesel fuel to improve cold flow properties when using the fuel in northern climates. For this reason it is also known as No. 1 diesel.
Since it is considered a motor fuel, and therefore taxed as such, IRS regulations allow for the addition of red dye, at the terminal level, to render it unsuitable as a motor fuel, and thus exempt from federal taxes. Typically, at the state level, state taxing authorities usually exempt it from state taxes when dyed according to IRS regulations.
In addition to a cold weather fuel, it is many times used as a fuel for municipal buses, as the emissions tend to be very low.
Sprague offers this fuel, both dyed and undyed, in several terminals, especially in northern New England areas.