Science and physics say magnets positively affect diesel fuel combustion

May 22, 2015 by Capt. Jeff Werner

OK, I admit it. I was skeptical at first. During one of my first jobs as a yacht captain back in the early ’90s, I flew to Mallorca where a yacht owner was waiting for me at the airport. We would depart Palma for Gibraltar about three hours later, just enough time to toss my seabag in my cabin and get oriented to the engine room and bridge.

As I checked out the main engines and both generators, I noticed a small and mysterious aluminum device fitted to the fuel lines between the tanks and the Racor filters of each. The owner, a retired mechanical engineer, told me nonchalantly they were “inline fuel conditioners” with magnets inside the aluminum housing, and they helped keep the diesel fuel clean.

Inline fuel conditioner uses magnets to increase combustion. PHOTO FROM AXI INTERNATIONAL

Inline fuel conditioner uses magnets to increase combustion. PHOTO FROM AXI INTERNATIONAL

I managed to keep a straight face, as time was of the essence and we had to cast off shortly. But during our passage, he gave me a scientific discourse on the theory of inline fuel conditioners and the permanent magnets contained within. Once we arrived in Gib, I had some free time and researched the subject, and I have been installing inline fuel conditioners on the yachts I have operated ever since.

Studies done on inline fuel conditioners show an increase in fuel economy due to better fuel combustion and cleaner fuel due to a dramatic decrease in the size and number of particles suspended in the fuel.

But how do these magnetic treatment devices work? First, let’s look at what diesel fuel is made up of by taking a trip back to your high school chemistry class and your brief foray into organic chemistry.

When petroleum is refined, it produces a variety of fluids that are composed of simple chains of carbon atoms bonded to hydrogen atoms. The number of carbon atoms in these hydrocarbon molecules determines whether the fluid is a gas, or a thin or thick liquid. The greater the number of carbon atoms, the more the fluid approaches a solid form.

For example, methane is a gas and is made up of only one carbon (C1) atom, while gasoline, a runny liquid, generally has six to 10 carbon (C6-C10) atoms per molecule. Asphaltenes or tars are viscous liquids that approach solids and may have as many as 30 carbon (C30) atoms.

Diesel fuel, which is thicker than gasoline but thinner than tars, has an average of 16 carbon (C16) atoms. This molecule of 16 carbon atoms is called cetane. Cetane ignites easily under compression, and compression is the basis of diesel engine operation. Therefore, in the ideal world, all diesel fuel would be composed solely of cetane molecules.

But in the real world, diesel is an imperfect liquid whose characteristics vary depending on the chemistry of the oil in the well and the techniques used to refine that oil. Add to it the fact that diesel fuel is inherently unstable and that as it ages it accumulates an array of waxes, tars and different-weight oils, it is easy to understand that there are thousands of organic particles of varying sizes in a teaspoon of diesel, not all of which combust efficiently in the cylinder of a diesel engine.

If these larger organic molecular chains could be broken down to smaller organic molecules that approach the combustibility of cetane, then a diesel engine would operate more efficiently. That is just what an inline magnetic fuel conditioner does.

As the diesel fuel flows through the inline fuel conditioner, it passes through a magnetic field created by the permanent magnets built into the aluminum housing. Research into chemical bonding has shown that the larger organic molecules in diesel fuel carry a slight electrical charge. And when a charged particle passes through the flux lines of a magnetic field, the magnetism exerts a force on that particle.

This force, named the Lorentz force after the 19th century Dutch physicist who discovered it, is a basic tenet of electromagnetism. This Lorentz force created in the fuel conditioner breaks the weak molecular bond of the larger asphaltene and heavier oil molecules and separates them into molecules with a smaller number of carbon atoms so they can burn more easily.

Using basic chemistry and physics, an inline magnetic fuel conditioner is an important part of a yacht’s fuel preventive maintenance program. And the best part is it has no moving parts and it has no filters to change. Just install it and forget it.

Capt. Jeff Werner has been in yachting for more than 20 years on private and charter yachts, both sail and power. He is an instructor for RYA, MCA, USCG and US Sailing courses and owns Diesel Doctor ( Comments on this column are welcome at


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