Diesel fuel tank sludge during storage a rising concern

Written by Erik Bjornstad | Jun 8 2015

Ultra low sulfur diesel’s tendency to form sludge at faster rates than in the past are forcing the marketplace to adjust in ways not anticipated in the past.

It used to be that you could expect to store diesel fuel for fuels without an issue. There are thousands and thousands of backup generators that have sat for years with fuel in their storage tanks that’s ten or fifteen years old. There’s no telling the amount of diesel fuel tank sludge and microbes and how it has destroyed the fuel quality within. How confident would you be in your emergency generator if you knew the stored fuel was ten years old?

When fuel sits for long periods, chemical reactions have plenty of time to break the fuel down. The fuel gets exposed to oxygen and water, the heat from the environment provides the energy, a few unstable molecules form and they react with healthy fuel.

Why is ULSD worse in this respect than in the past? The processing of the fuel to remove the sulfur changes its composition, yielding components that are more sensitive to sludge formation. Not to mention a lot more sensitive to microbial growth (the sulfur used to inhibit this, but it’s not there any more), which can break down fuel quality even faster.

Diesel fuel sludge is a problem to you on several fronts.

Since it was once part of the fuel, you’re losing fuel energy value if it drops out.
If it does burn, you get a lot more black smoke emissions
It forms injector and combustion chamber deposits (because it’s heavier than fuel and doesn’t burn completely), both of which destroy engine/machine performance over time

Best practice recommendations to ensure your systems aren’t affected by fuel sludge dropout are to treat the fresh fuel with a stabilizer, and do annual fuel and fuel tank health checks.

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