Biocides

[Mike4116]

I see on this forum that there is often a discussion around the use of biocides in diesel fuel. I have often wondered why the refineries don't put a biocide in the fuel during the refining process. That way the biocide would be in the fuel from the very beginning and reduce the incidence of organic growth in their product. In my part of the world, Michigan, diesel sits in the storage tanks in marinas throughout the region for the entire winter. This is another opportunity for critters to grow in the stored fuel and create a mess in the spring when the stuff is finally sold to consumers. I'm pretty sure that marinas don't put a biocide in the storage tanks in the fall. If they do it will be a welcome piece of news.Just wonderin'.... if anyone has further info on my questions I'd welcome the information.

 

[MoonSailer]

Some Marinas Do add Biocide

I have had mixed results at marinas and service stations. I bought some contaminated diesel at a Texaco service station and at a Marina in Dog River Alabama. The marina was much worse. I have also bought some very clean diesel at service stations and marinas. I have a West Marine fuel filter funnel tha I use when buying fuel. It is supposed to catch water and most debris. Most places that I have bought fuel the funnel is empty but I have bought fuel that had water and crud. A lot seems to depend upon how much business the supplier has. I guess a low volume dealer might have fuel that is years old. I am sold on ULSD it just looks clean!!!! The process that removes the sulfur also removes the nitrogen and probably the phosporus and definately lowers the ash content. All life needs phosphorus and nitrogen to grow. Without these nutrients less stuff seems to be growing in my tank. I still use a biocide and keep my tank less than 1/2 full to control growths. I figure that there is no advantage to using old fuel.

 

[Paul Akers]

Texaco Valvtec...

...has a biocide in it. I asked the marina manager just yesterday (a Nordhaven captain was with him. They hac=ve a Nordhaven dealership at the marina) and he told me they still do, but don't rely on it over the winter. Both people said to use a biocide for storage along with a stabilizer to preserve the diesel fuel. The Texaco biocide is OK when you are burning the fuel during thr season.

 

[larry w]

fuel up

The fuel dock in my marina is a Unocal (Union Oil) dock, and they have a conditioner and a biocide already in their fuel. I've fueled up at other docks tho, not owned by a major oil company, that don't.

 

[Gord May]

Keep it dry

From the Chevron (Texaco) Diesel Fuels Technical Review:http://www.chevron.com/products/prodserv/fuels/diesel/documents/Diesel_Fuel_Tech_Review.pdfDiersel Fuel BiocidesThe high temperatures involved in refinery processing effectively sterilize diesel fuel. However, the fuel may quickly become contaminated if exposed to microorganisms present in air or water. These microorganisms include bacteria and fungi (yeasts and molds).Because most microorganisms need free water to grow, biogrowth is usually concentrated at the fuel-water interface, when one exists. In addition to the fuel and water, they also need certain elemental nutrients in order to grow. Of these nutrients, phosphorous is the only one whose concentration might be low enough in a fuel system to limit biogrowth. Higher ambient temperatures also favor growth. Some organisms need air to grow (aerobic), while others only grow in the absence of air (anaerobic).The time available for growth is also important. A few, or even a few thousand, organisms don’t pose a problem. Only when the colony has had time to grow much larger will it have produced enough acidic byproducts to accelerate tank corrosion or enough biomass (microbial slime) to plug filters. Although growth can occur in working fuel tanks, static tanks, where fuel is being stored for an extended period of time, are a much better growth environment when water is present.Biocides can be used when microorganisms reach problem levels. The best choice is an additive that dissolves in both fuel and water to attack the microbes in both phases. Biocides typically are used in the concentration range from 200 to 600 ppm.A biocide may not work if a heavy biofilm has accumulated on the surface of the tank or other equipment, because it may not be able to penetrate to the organisms living deep within the film. In such cases, the tank must be drained and mechanically cleaned.Even if the biocide effectively stops biogrowth, it still may be necessary to remove the accumulated biomass to avoid filter plugging. Any water bottoms that contain biocides must be disposed of appropriately because biocides are toxic.The best approach to microbial contamination is prevention. The most importantpreventative step is keeping the amount of water in a fuel storage tank as low as possible, preferably at zero.

 

[Steve O.]

in the North country

I personally don't believe it gets warm enough for long enough in Michigan to promote bio growth. In 20 yrs. of sailing I have never experienced or known anyone who had a bio problem. Keeping your fuel dry and your filters clean is the best preventitive.

 

[agaliha]

half ounce of prevention

12 years ago I bought a used sailboat with an aluminum diesel fuel tank. The previous owner had not used biocides. In this hot and humid climate (Tennessee) the tank had become infested in a colony of micro organisms. After a year of trying every trick in the book, I eventually took a sawsall (with metal cutting blade) to the tank and removed it piece by piece. I replaced it with a much smaller plastic tank. This totally solved the problem of clogged fuel filters. I was spending more on filters that I was on fuel. And they clogged at the most inopportune times! Since that time I have added a very small amount of Biobor to the tank everytime I add fuel. It's a half ounce of prevention that saves a very pesky problem. Farmers here say that the only way to clean a contaminated tank on a diesel tractor is to remove the tank and steam clean it, which can't be done in a sailboat. With the recent rise in average temperatures, this problem will only become worse. Sailboats are particularly succeptible because fuel consumption is so low and therefore fule sits in the tank longer.