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New diesel advances mean more cold flow problems

Posted by: Erik Bjornstad

cold flow problemsI have a friend moving to North Dakota and she posts updates on what the temperature is like on a given day up where she’s getting ready to move. Right now, they’re looking at wind chills in the single digits, and we’re just headinginto November.

If you live in Illinois or New York or basically anywhere except Florida and the Deep South, you’re nodding your head right now. And if you’re in charge of diesel equipment or a stored diesel fuel supply, you may already be making (or have made) plans to treat the fuel for cold flow improvement.

But what you may not know is that the traditional measures and expectations for cold flow temperatures of diesel fuel are changing. And not for the better. If you don’t take this into account, you run the real risk of expensive problems when you don’t expect them.

Better Diesel Filters Mean More Problems In The Cold

When making decisions about what to do on the cold flow end, you have to anticipate when you’re likely to have problems. How cold does the weather need to get before you start worrying?

It’s most common to rely on experience when it comes to judging the problem temperatures for fuel.  All fuel has a cloud point – the point at which stuff formerly dissolved in the fuel starts to become undissolved.  The temperature below the cloud point, at which you could expect filter plugging problems normally runs about ten degrees below the cloud point. So if the fuel you use normally had a cloud point of 15 degrees F, you know you were good down to maybe 5 degrees F. It never gets that cold in Florida, but up in Wisconsin and Michigan, you can bet it’s going to be in that range every single winter.

Enter the new diesel engines.

The newer generation of diesel engines are forcing operations personnel to rethink the conventional wisdom on this, because the newer diesel engines use secondary filters with smaller holes. It used to be that 10 microns was the standard filtering size.  Now these engines are spec’ing 7 or 5 or even as low as 2 microns.  The purpose for the change is to filter out as much of the smallest particulates from the fuel as possible, to protect expensive parts.

But the secondary consequence to this is that filters that used to let fuel with a cloud point of 15 degrees, they would let the fuel pass without a problem. With smaller holes, more and more of these fuels are going to plug filters at temperatures higher than before.

How high for cold flow problems?

The new recommendations are to adjust your expectations higher towards the cloud point temperature and away from the plug point temperature.  The smaller the filter, the higher the temperature that you’re going to experience shutdowns in cold weather.

If you use a 7 micron secondary filter, they recommend expecting problems about halfway between the cloud point and plug point temperatures.

If you use a 5 or a 2 micron filter, they recommend just using the cloud point as the “new plug point”.  That means you should expect to have plugging problems at temperatures maybe ten degrees higher than before.

Anything else you can do?

Sure. Just make sure you’re getting your cold flow treatment into the fuel early enough in the season.  Cold flow treatments (like Cold Flow Improver) only work if they’re present in the fuel before the cloud point causes paraffin to start dropping out. 

So you’ll want to be treating the fuel for cold flow earlier in the season if you could be having plugging problems ten degrees higher than before. 

You may be interested in these other posts:

Cold Flow Improver

Fuel Additives for Winter


This post was published on December 9, 2014 and was updated on January 20, 2016.

Topics: Diesel