AST: Above-ground Storage Tanks
Location of an AST varies dependent on the type of power system being used, but these tanks are often located in open areas in contact with direct sunlight, rain and fog, and organic matter, such as vegetation and dust.
They are often positioned in contact with engine heat, which causes changes in fuel temperature and accelerates the aging process.
Underground Storage Tanks
Placement of a UST commonly occurs under sidewalks, parking lots and driveways. For this reason, these tanks are often impacted by issues of poor grading, water run-off, low ground water levels and the collection of organic matter and debris in spill buckets.
Limited Shelf-life
We all know diesel fuel has a limited shelf-life. After about 28 days from the day of manufacture, gums, resins waxes and asphaltenes begin to form within the fuel. This process is known as Amalgamation. The rate of amalgamation will vary due to several factors, including today’s modern refining techniques, low sulfur content and storage tank environment.
Aboveground and Underground Storage Tanks
FUEL MATTERS
Regular Test Runs Impact Fuel's Shelf-life
Exercising and Load Bank Testing
Regularly testing of emergency power systems requires regularly scheduled startup of the genset, as well load bank testing to assess and verify the systems performance capabilities. While this an essential part of any preventative maintenance practice, startup and load bank testing impact fuel stability and shelf life.
As fuel is pulled into the engine, it is heated prior to combustion. When the engine has stopped running the residual fuel is then returned back to the fuel tank. This drastic change in temperature accelerates the aging process (amalgamation), thickening the fuel; impacting fuel quality and combustibility, especially in higher-pressure pumps and injectors. With each engine start, lower quality fuel is returned to the tank, where it accumulates over time.