Written on: September 18, 2017 by John Levey
I’ve recently seen (online) and heard (in person) several discussions about today’s fuel quality and it’s supposed relation to service issues.
I use the word “supposed” because it seems that some people tend to blame all of our problems on something they believe to be “new.” We had “fuel quality” issues when I started in the field back in the 1960’s, long before anyone thought of bio-fuels or low sulfur heating oil. After looking into some of the issues being reported today, I believe that the same things that caused problems decades ago are still causing problems today, and the #1 cause of many of those problems is water in tanks.
You’re all probably familiar with the credit card advertising program that asks “What’s in your wallet?”
As I think about fuel quality and service issues the first question I think should be addressed is “what’s in your tank?” After a bit of research it doesn’t seem that the quality of fuel being provided by reputable suppliers is the issue. The issue that I’ve seen is the quality of fuel in our customer’s tanks.
This picture shows tank bottom samples of 4 randomly selected above ground tanks (Figure 1).
The sample on the left is obviously much cleaner than the other samples which get progressively worse as you look from left to right. The haze that’s visible in the two middle samples is suspended water.
While these samples might seem “normal” to those of us in the industry for some time, it’s important to keep in mind that oil tanks have changed over the years and samples like these should not be the norm.
Up until the early 1990’s standard above ground tanks were typically installed with longer legs at the end of the tank where the outlet was and shorter legs at the other end. This kept water and sludge in the tank and, in theory, supplied cleaner fuel to the oil burner. However, it also led to the accumulation of water and sludge in the tank bottoms as well as a number of other problems.
For the last 25+ years above ground tanks have been equipped with a bottom outlet. If these tanks are properly installed, with a minimum of 1/4” per foot slope towards the bottom outlet, water won’t build up in the tank bottoms and the oil in the tanks should be much cleaner than it was pre-1990. See Figure 2. In theory, if a tank is pitched properly, any water that falls to the bottom will be eliminated from the tank through the bottom outlet and trapped in the filter.
However, not all tanks are installed properly, many are still pitched away from the bottom tapping and allow water to accumulate. This brings us to the first recommendation of this article – Install tanks properly! Read and follow the instructions and you’ll avoid problems.
Why is keeping the water out such a big deal?
Water in fuel tanks leads to fuel degradation and enables the growth of microbes (bacteria or fungus) that thrive at the oil/water interface. Their presence leads to acid formation, corrosion, fuel degradation and service issues such as filter plugging, tank failure, etc.
I was recently involved in testing a random sample of 150 above ground residential fuel oil tanks with Mark Stellmach of Fuel Management Services. We conducted Liquidcult microbial tests and found that 53% of the tanks tested positive for contamination, with 16% showing moderate to heavy bacteria and 37% showing moderate to heavy fungus. (Figure 3)
It’s important to understand that fuel degradation occurs over time even without microbes. All fuels oxidize over time and as they do acids are formed that transform into polymeric gums – “sticky stuff” that can clog filters, bind fuel units, etc.
These pictures show a fuel sample that contains water on the bottom and the sample jar shows the polymeric gums sticking to the bottom of the jar when turned over. (Figure 4)
So back to fuel quality & service costs – yes, they are most definitely related.
The good news is that it’s not that hard to keep service costs in line – KEEP WATER OUT OF YOUR CUSTOMERS TANKS! ICM