Free water and water in solution can result in an expensive repair bill for High-Pressure Common Rail fuel systems
BRANDON — Today’s diesels are particularly picky about the fuel we feed them. A small particle that wouldn’t have been noticed on previous generation engines can attack performance on a 2023 engine.
Users may think buying fuel from a local high-volume dealer is a guarantee that it’s as clean and pure as the day it left the refinery. Wrong.
In fact, contamination might have started before the fuel even left the refinery, according to AXI, a Paris-based university that is a leader in fuel technology including innovative fuel polishing and filtration systems.
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The AXI website says all fuels contain some water in suspension. However, diesel fuel is less refined than gasoline and therefore holds more water. This water can cause severe problems with water separators on the equipment. It can also cause the fuel injector tips to explode, resulting in expensive repairs.
The two types of water contamination are water in solution and free water.
Water in solution is reported in parts per million (ppm), says David Harvey, manager of product and technology at Citgo.
“There are various reasons that a diesel fuel may contain water in solution. Among them are condensation of water in a fuel tank, components in the diesel fuel which help to retain the water in solution, and fuel temperature.”
Because of differences in chemical properties, water does not normally exist in high concentrations in diesel. The two liquids typically separate, with water dropping out and accumulating at the bottom of the tank.
Water that drops out instead of dissolving is called free water. It is suspended rather than dissolved. Free water can separate from fuel because of agitation, as with a fuel tank travelling over a rough road or field.
Diesel bug is the general term for microbial growth such as bacteria and fungi that thrive in the zone where water interfaces with fuel. It feeds off alkanes and additives.
There are approximately 100 different types of bacteria, moulds and yeasts found in diesel fuel. Microbial contamination is considered the most harmful of all fuel contamination.
“The most common cause of free water in diesel fuel is poor housekeeping of storage tanks. The most common cause of water in solution is the composition of the fuel itself or additives which help to dissolve that water into a solution,” says Harvey.
Water in fuel reduces the energy available, lowering horsepower. Water in tanks, lines, injectors and filters will freeze more readily than the fuel itself.
Most diesel fuel without additives freezes at about -30 C, which is workable for most winter work. Without additives, water trapped in the system freezes at 0 C.
Whether dealing with free water or water in solution, the result can be an expensive repair bill, according to Keller Equipment rep Jason Thiessen.
“Because of the extremely high pressures with High-Pressure Common Rail (HPCR) fuel systems, this damage is even more pronounced in newer equipment.”
Delivering fuel to the farm is a relatively closed system. At least, it should be. But there’s an opportunity for contamination every time a cap is opened or a nozzle inserted into the implement’s fuel tank.
“Outdoor farm tanks typically get moisture in them through condensation. It can’t be helped,” says Thiessen. “When you’re filling the tank in your yard, the vent at the top expels air from inside. That’s good.
“But it works just the opposite as you draw fuel out. Now you’re sucking air into the tank. If it’s a high humidity day or a dusty blowing day, that’s the air that will go back into the tank.
“The same thing happens with your equipment in the field. Think of how dusty it can be when you’re seeding or combining. As you run the equipment, you draw down the tank and suck that dust into the fuel tank. You can get filters to remove the moisture going into the tanks.”
Thiessen’s booth at Manitoba Ag Days displayed a GPI modular pump, filter and meter. The 12-volt system handles 20 gallons per minute at the nozzle. The complete kit sells for $1,500.
