Upgrading to newer and better ground-level fuel storage facilities may not be in everyone’s future, at least in the short term. Many family and smaller-scale operations may not be able to justify the additional investment expense. Here’s a look at how to make do with existing overhead storage tanks for as long as possible.
According to Alberta Agriculture and Rural Development (AARD), there are steps farmers can take to improve the safety and quality of storage of older, overhead tanks.
First, you have to ensure the fuel quality remains high. Contaminants can really cause trouble in a vehicle’s precision fuel metering system. Ensure your storage tanks don’t add to the problem. Equipping them with water and sediment filters is a good first step.
“Filters and sediment bowls on overhead tanks will minimize the chances of contaminating equipment fuel systems,” according to AARD. “The filter should have enough capacity to pass fuel at the usual rate of filling. The recommended size of filter is 10 microns. This size is sufficient for removing microscopic particles of rust, sand, dirt, scale and lint.” Be sure to change the filter elements regularly to keep them functioning properly and prevent restricting the flow rate.
And avoid drawing fuel out of a storage tank within 24 hours of a fuel delivery. Giving the fuel time to settle will likely allow sediment to fall to the bottom of the tank below the discharge opening.
Fuel in an overhead farm storage tank should be tested annually. To do so, fill a clear onelitre container and allow it to sit long enough to let any contaminants or water settle to the bottom (diesel is less dense than water). If the sample is clear, use a clean stick to agitate the contents of the tank through the fill cap and fill the container again. If there is contamination this time, consider draining the tank through the bottom drain plug and cleaning it. The ideal time to do this is after it runs empty and before a refill. Flushing it with clean fuel could wash out much of the loose sediment.
When draining or flushing a tank, collect all the fuel and dispose of it safely. Don’t let it drain onto the ground, or it could easily end up in your water well.
STORE IN THE SHADE
Extreme temperature fluctuations can shorten the time it takes fuel to degrade, so placing overhead tanks in a shaded area will ensure your stored fuel stays healthy for as long as possible. Tanks positioned in direct sunlight will have large internal temperature swings. That also makes them more likely to suffer from water condensation. Also, higher temperatures can speed up the evaporation rate of your expensive fuel.
A University of Nebraska test showed a dark-coloured fuel tank, which creates high internal temperatures, lost fuel to evaporation roughly 40 per cent faster than a light-coloured tank. Adding a pressure-ventilated cap reduced losses by another 50 per cent. Together, just painting your tank white, or some other reflective colour and adding a vent cap can reduce losses from these sources by 75 per cent.
The amount of fuel lost in the Nebraska test was considerable. The relatively small, non-vented, 265-gallon dark tank used in the test was placed in direct sun and lost 8.4 gallons per month in the summer. In comparison, a white tank positioned in the shade and equipped with a vent cap lost only 1.1 gallons. The difference, 7.3 U.S. gallons, equates to about 27.6 litres. Figure fuel cost at, say, 75 cents per litre, that means an additional loss of roughly $20 worth of fuel in a month from one small tank.
Even in a best-case scenario, a white fuel tank in direct sunlight still lost 2.6 gallons per month. Moving it or building a structure to shade it will still reduce evaporation losses by more than 50 per cent.
If that motivates you to reposition your old tanks to a shady spot, consider adding a secondary containment system to deal with any potential leaks. Remember, nearly all of those old tanks have single-wall construction. If it starts to leak or you accidentally knock it over, that could be a big spill. And while some provinces don’t regulate above-ground farm storage facilites — yet — they do require farmers to report significant spills. And fines could be levied. That would be more money down the drain.
Also, consider adding a protective structure to prevent accidental contact with the tank stands. A steel pipe filled with concrete and solidly secured in the ground makes a good barrier.
For information on how to construct secondary containment systems, check out “Farm Fuel Storage and Handling -Planning Your Fuel Storage Site -What You Need to Know” on the AARD web-site, www1.agric.gov.ab.ca.