Budget Busters For Municipalities - Cold Flow Problems

As winter approaches, we’re reminded how challenging cold weather can be for local and private organizations that rely on stored fuel—city and county fleets, as well as small and mid-sized businesses. Tight budgets make it difficult to plan for the season ahead, especially when unexpected equipment problems show up year after year.

Diesel fuel gelling problems are the big one for this time of year. Bell Performance has been located in Florida since the mid-1930s (thanks, Robert J. Bell!), so we don’t see fuel gelling during the winter time in our neck of the woods. Unless someone is using high-concentration biodiesel blends – those can gel when the temperature drops down to just 45 or 50 degrees F. But that's less common than you might think.

If you’re responsible for maintaining buses or trucks or diesel equipment up north – New York, New Jersey, Chicago, Boston, Michigan – you can’t afford to ignore what the cold does to diesel fuel. And what it does to the equipment running on it. Nothing will shut down a diesel engine faster than a fuel filter clogged with wax dropping out of gelled diesel fuel. Then there’s the expense of downtime, lost service, towing, service time, and work. Not to mention the headache of a sizeable unexpected cost that will sap the budget.

Knowing Your Fuel's Temperature

Professional fuel users have a good idea when they need to add a cold flow improver because they generally know the cloud point and plug point temperatures of their fuel. They keep track of outside temperatures so that they have an idea ahead of time when they need to get that antigel treatment into the fuel so its there before the fuel gets too cold.

As a user, you want to start considering cold-weather treatment when the temperature starts coming within 10 degrees of your fuel's cloud point. For most diesel fuels, the cloud point is, say, 18 degrees F. This means, if you're tracking the ambient temperatures for your area when the forecast starts projecting lows that approach 10 degrees above that, you're looking at a threshold of 28 degrees. Basically when the outside temperature first drops below freezing, you're going to set your antigel treatment plans into motion.

Indeed, preventive maintenance is the name of the game to keep problems from happening. Treating the diesel with a cold-flow antigel agent is the only effective way to eliminate these incidents. Cold flow fuel treatment is a relatively low-cost option that can be easily factored into the budget.

What About Kerosene?

Kerosene is a more traditional solution for lowering diesel's cold filter plug point, working on the principle of dilution of the paraffin waxes in the fuel. It does work, but you need to keep some things in mind if you elect to go this route vs. using a cold flow improver.

The biggest performance difference with kerosene vs. a good polymer-based anti-gel is that kerosene provides less of a drop in temperature. A typical fuel anti-gel should be able to drop a fuel's cold filter plug point by, say, 15 degrees - but at a relatively low treat rate like 1:1000. It does depend on the fuel's characteristics, but 15 is a reasonable expectation.

Kerosene dilution works off the rule of thumb that you can expect about a 3-5-degree drop for every 10% kerosene you use. So if you needed to drop your diesel's gelling temperature by 15 degrees, you'd need to use a 50-50 blend of ULSD and kerosene. At such sizeable amounts, you'd also have to factor in the loss of mileage you'd be getting with kerosene, which has less energy than #2 diesel and therefore will give you less mileage.

So yes, kerosene will work, but you need to be realistic in accounting for how much you'll need to use to get you where you want to be.

Is there anything to be done for an agency’s fuel that has already gelled to the point where it’s shutting engines down? In these cases, there are "quick thaw" rescue treatments that typically function to melt gelled fuel in a fuel system. These emergency treatments are fairly inexpensive and can be included in a preventive maintenance budget without creating too much pressure.

You may be interested in these other posts on cold flow problems:

• Diesel fuel lubricity trends for fleet and business
• How to Prevent Diesel Fuel Contamination
• Prevent Your Diesel Fuel from Gelling in Cold Temperatures