Urea – More Things to Consider

Urea - More Things to Consider

I recently heard a new concern for those of you who will be storing and dispensing Urea for the 2010 diesel trucks. Urea is a very corrosive product that can quickly damage metal tanks, some types of seals, even dispensing nozzles.

Most fuel dispensing nozzles are made from nickel plated aluminum. When Urea is dispensed through such a nozzle, the nickel plating will react changing the Diesel Emission Fluid (DEF) to where it can cause damage to the SCR (Catalytic Converter) system.

The longer the Urea is in contact with the nozzle the more potentially damaging the fluid will become. What this means is that in high volume situations, the fluid will have limited contact with the nozzle and the likelihood of fluid being contaminated is significantly reduced. In lower volume situations where there may be extended periods of time between use, there is a higher likelihood of contaminating the fluid.

It may be desirable to go to a nozzle made of unplated metal or possibly even a composite material to prevent this contamination.

It is considered vital that a non-fuel nozzle be used to prevent the possibility of accidentally adding diesel to the DEF or DEF to the Diesel Fuel. Either mistake will likely cause rapid and catastrophic failure of the engine and or the SCR System.

In Europe a company called ElaFlex provides the defacto standard for AdBlue (Urea) nozzles that have a unique feature that prevents the AdBlue (Urea) from being added to the fuel tank.

ElaFlex has recently signed an agreement with OPW to provide these nozzles to the US and Canadian markets.

We will be providing a comprehensive list of suggestions on how to safely and cost effectively dispense Urea for your fleet operation.

Diesel Doctor

Copyright 2009 – William Richards

US EIA – Information on Gas and Diesel Pricing from the US EIA

US EIA – Energy Information Administration

The US Energy Information Administration provides daily information on regional, national, and worldwide inventories, pricing, and availability. You can view this information at: http://tonto.eia.doe.gov/oog/info/gdu/gasdiesel.asp

You can also view a copy of this webpage and other related information at: http://http://www.lcbamarketing.com/

We will be exploring what goes into the price of fuel at the pump over the next several weeks.

Check back every day.

Please post your comments, suggestions, and ideas here.

Diesel Doctor

Copyright 2009© - William Richards

Cetane Number – What it is and Why it’s so Important

Cetane Number – What it is and Why it’s so Important

Cooperative Fuel Research Engine (CFR)

Cetane is a measurement of a diesel fuel ignition and or combustion quality. This Cetane Number or CN is one of several components that determine the quality of diesel and biodiesel fuels. This number is used for light and middle distillate fuels. For heavy (residual) fuels Calculated Ignition Index (CII) and Calculated Carbon Aromaticity Index (CCAI) are used.

In some ways this measurement is similar to the Octane Ratings given to gasoline. In its simplest terms Cetane Number measures the delay between the start of fuel injection into the combustion chamber and the beginning of compression ignition (Auto-ignition).

In medium and high speed diesel engines (this all automotive and truck engines) fuel needs to have a CN between 38 and 55 to operate. In general the higher the CN number, the better for the engine and for emissions. However raising CN above 55 currently offers little if any benefit.

In the US the group setting the standards for CN is the American Society for Testing of Materials (ASTM) and currently the minimum is 40. While diesel engines will start and run with 40 CN fuel, they do not run as efficiently as they will at a higher number.

In Europe the European Union (EU) has systematically over several years raised the minimum from 38 to the current 51. This has allowed engine manufacturers to produce more efficient engines with lower emissions and better economy. Most fuel in the EU has a CN of 55 or even better.

Cetane Number is measured using a very expensive and arcane Cooperative Fuel Research (CFR) engine and a process that very complex.

You can also measure CN using an Ignition Quality Tester (IQT) which is somewhat less complex, but still quite costly.

There is a third measurement called Cetane Index (CI) that measures density and distillation range of the fuel and through a calculation provides a measurement. This method will calculate a reasonably accurate number for the refined diesel.

The problem is that today most diesel fuel uses additives to reach the desired Cetane Number and additives do not affect the density, thus the CI of a fuel containing additives is not accurate.

Some of you may have seen a device that looks like a battery fluid tester (a hydrometer). These devices are not capable of determining CN or CI with any accuracy.

You can raise CN by altering the refining process or through the use of Alkyl nitrates or di-tert-butyl peroxide additives. NOTE: Remember that additives do not raise CI.

Also, biodiesel, depending on the base oil from which it is derived has a natural Cetane Rating of 46 to as high as 60.

With the advent of Pilot or Multiple Pulse fuel injection, Cetane Number becomes more important than ever. The delay in auto-ignition (CN) affects the combustion timing, which has a significant effect on power output, fuel economy, and emissions.

Raising Cetane Number together with Improving Fuel Atomization is the fastest way to improve fuel economy and reduce emissions through the use of correctly formulated additives.

Please post your comments, ideas, and suggestions

More information at: http://www.lcbamarketing.com/ - Click on Fuel School Articles.

Diesel Doctor

Copyright 2009© - William Richards

Asphaltene's and Plugged Fuel Filters

Asphaltenes and Plugged Fuel Filters

Asphaltenes in diesel fuels are becoming a much larger problem since the introduction of Ultra-Low Sulfur Diesel (ULSD - S-15) fuels.

There are actually several problems that have come together to cause the filter plugging black slime we so often see today.

Asphaltenes are highly polarized long chain components in crude and the heavier refined oils. Under certain circumstances these compounds associate themselves to form complex colloidal structures.

In Low Sulfur Diesel (LSD – S-500), High Sulfur Diesel (HSD – S-5000) and heating and bunker fuels the higher aromatic content of the fuel tends to discourage the formation of the complex colloidal structures limiting the problem.

However the EPA mandated reduction in aromatic content in ULSD has allowed this problem to happen sooner, more often, and in cooler temperatures than had been seen previously.

Asphaltenes agglomerate into an oily sludge. This problem is made worse when water is added to mix.

Petroleum and bio-derived fuels all hold water suspended in them, ULSD unfortunately holds approximately twice as much as the LSD and HSD fuels we had seen prior to June of 2006. Biodiesel (B100) can hold ten (10) times as much water as LSD and HSD, so even small amounts of biodiesel blended with diesel fuels dramatically increases the amount of dissolved water present.

Blending of fuels refined from different crude stocks further exacerbates this problem. Also, warmer temperatures in storage or due to the recirculation of fuel by the engine fuel system speeds the process and thickens the sludge.

Fuel that looks perfect going into a clean tank can develop tiny asphaltene droplets in a matter of hours when recirculation temperatures exceed 140°F (note: some newer engine fuel temperature as it exits the head exceeds 210°F). These pin-prick sized droplets can plug a 10 micron fuel filter in 3ooo to 4000 miles or less 50 hours of operation.

Many people mistakenly see this as a biological (bacteria and fungi) problem, however in the majority of cases the accelerated biological growth is the result of near perfect growing conditions that allows this rapid growth after the filter plugging asphaltene material has blocked the filter(s).

Keeping the water out helps, but the real solution is a thermal stability additive, a oxidative stability additive, together with a water dispersant.

Please comment with your experiences, suggestions, and or questions.

Diesel Doctor

Copyright 2009©

Fuel Storage Tank Maintenance - Keep It Clean

Keep It Clean - Fuel Storage Tank Maintenance

Most owners and operators of fuel storage tanks do not understand that maintenance is required to safely and successfully operate fuel storage tanks.

We constantly hear that customers have tanks that have never been cleaned and worse yet, that they believe that they never need to check to see if they have any problems.

This is made even worse by the information that some fuel suppliers tell their customers; for example that it OK to have some water at the bottom of the tank.

Well here is some real world information for everyone on this subject.

Fuel Storage Tanks all require regular maintenance. They are designed with the pickup tube 3" to 6" from the tank bottom so that small amounts of water, sediment and other contaminants have a space they can settle out so that they will not be drawn into the vehicle or equipment tanks as fuel is pumped out. This water and sediment material will accumulate over time and will cause problems if not removed periodically.

Some will tell you that 1/2" or 1" or even 2" of water is alright, and they are flat out wrong. Every time fuel is transferred into that tank it stirs up all that material and it may take as long as a day for it to settle out again. In the meantime every tank you dispense fuel into gets some of this material.

If you have a steel tank that water is corroding your tank from the inside out and putting rust particles into your fuel. We often find above ground tanks only a few years old that have rusted from the inside to the point of leaking from water and sludge in the tank.

Many customers have electronic monitoring systems that provide constant readings showing fuel level, water level, and leak detection. Some of these customers will see 1/2" or a few gallons of water on these system and ignore it because they have been told it is not important.

One problem we see time and again is that the sensors on these monitoring systems fail and they don't tell you when they fail, they just go on showing the last reading forever. This goes on until they start pumping water into their equipment at which point someone checks the tank with a stick and water finding paste only find that they actually have several inches of water.

We have told all of our customers for many years that even though you have spent several thousand dollars for a state of the art monitoring system, you still need to have some one check every tank at least once a month with a stick and water finding paste.

And this rule should be written next to the monitor and maybe next to where you store the measuring stick: "The Only Acceptable Amount of Water in Any Fuel Storage Tank is ZERO (0)".

For those of your with in-ground steel tanks, these tanks have Sacrificial Anodes attached to them. These Anodes take the weak electrical current generated by the tank and pass it into the ground through them. This prevents the tank metal from corroding, however the Anode "Sacrifices" itself in this process. The Anode is used up over a period of time. When the Anode is "used up" the tank begins to corrode often very quickly. Tank owners should periodically check these Anodes and Replace them as necessary. In many states this is part of the required maintenance and testing procedures, however you should know this and check to be certain it has been properly done.

Caps, Sumps, and Vents should all be checked for integrity and to see that they are doing their intended job.

Fuel Storage is a vital link in getting clean fresh fuel safely and efficiently into vehicles and equipment. You have a big investment in the tank, its installation, and in the fuel in it. It only makes sense to properly maintain and protect this investment.

Today we have new challenges with Ultra-Low Sulfur Diesel (ULSD), Biodiesel, Gasohol, Conventional Gasoline, and Reformulated Gasoline containing any amount of Ethanol. These fuel products hold much higher levels of water and are much more corrosive than fuels we have traditionally dealt with. They require much higher levels of monitoring and maintenance to have a safe and trouble free delivery system.

We are happy to offer analysis and suggestions on how to operate and maintain your systems.

Please post your comments or questions here.

Diesel Doctor

Ultra-Low Sulfur Diesel Cold Weather Information

Ultra-Low Sulfur Diesel Fuel

Cold Weather Information

The Ultra-Low Sulfur Diesel (ULSD (S-15)) that we started to receive in mid 2006 has shown some dramatically different cold weather characteristics from the earlier High Sulfur (HSD (S-5000)) and Low Sulfur Fuels (LSD (S-500)).

These new characteristics including higher temperature gelling, wax dropout, icing, and difficulty in treating have in the first year and will continue into the foreseeable future to provide some significant challenges to distributors and end users during cold weather.

Due to these new characteristics users in areas of the US where they have not seen cold weather problems in the past, are now and will continue to see serious issues with gelling, wax dropout, and icing.

Here are the main issues known today:

Wax in diesel fuels – Paraffin wax is a natural and important part of diesel fuel. This wax provides several beneficial characteristics including high energy content (Btu’s), lubricity, stability, and viscosity. The negative characteristics mainly revolve around cold weather operation and include gelling and something new we refer to as wax dropout.

In HSD and LSD the wax characteristics were relatively well understood and consistent. For example the “Rule of Thumb” used for adding kerosene (#1 diesel, Jet A) to #2 fuel to lower Cold Filter Plug Point (CFPP) was that for every 10% kerosene added to #2 diesel you would lower CFPP by approximately 5°F. An example would be that a 50% blend would have improved CFPP by about 25°F.

However the new ULSD has had several important characteristics changed by the new refining processes. The catalytic cracking and hydrodesulfurization processes remove some of the wax, it alters the size and shape of the wax seed crystals in the fuel, lowers the aromatic content of the fuel, removes a significant amount of the Lubricity, and lowers the fuels ability to dissipate static electricity by as much as 100 times.

The result of this is that the ULSD fuel actually will gel at a higher temperature than the old LSD and HSD. This problem is made more difficult because we can no longer use regular kerosene (#1 diesel, Jet A) for cold weather blending. These fuels are considered High Sulfur and their use would cause the end fuel to have sulfur content higher than the allowable 15 ppm. So refiners have had to create an ULSD #1 specifically for winter blending purposes.

There are a number of problems with this new fuel. First, it is currently very expensive, ranging anywhere from $.30 to $1.00 more than regular kerosene, second it is not available in all areas, and third this new ULSD #1 is not as effective at lowering the Cloud Point (CP) and CFPP (gel point) of the fuel. For example; ULSD #2 when blended with 10% ULSD #1 will lower the CFPP by only 2°F or maybe 3°F. This means that a 50% blend would only improve CFPP by 10°F.

To make this problem even more difficult, many of the diesel fuel anti-gel additive products that have been on the market for last 5 to 30 years have little or no effect on ULSD. The change in fuel chemistry brought about by changes in the Catalytic Cracking processes and the addition of Hydrodesulfurization have rendered many of the most popular products nearly useless in ULSD.

There is a new cold weather problem that the industry has not adequately defined
as of today. We are calling this issue “Wax Dropout”. Wax Dropout occurs when diesel fuel is “cold saturated”. This where the fuel reaches a given temperature and stays at or below that temperature for a given period of time. This time period is usually between 48 and 72 hours or longer and the temperature can vary with different batches of fuel. This past winter we saw this problem at between 5°F and 10°F.

When the fuel gets to the Wax Dropout temperature, say for example 8°F and stays there for 48 to 72 hours, the wax will suddenly agglomerate and fall to the bottom of the container. This wax plugs filters and fuel lines until it is removed or until the fuel temperature is raised to a point where the fuel will reabsorb the wax.

Again there is a further complication, in that the “old” HSD and LSD wax would gradually start to reabsorb as the fuel temperature rose. With ULSD when wax dropout has occurred the wax does not begin to reabsorb until the fuel reaches fairly high temperatures, often above 40°F, 50°F or even higher. This can make the process of getting an engine with gelled fuel to run properly far more challenging than we have ever seen before.

In the fuel distribution and fleet operations businesses, we have relied on CFPP as
a measure of winter fuel quality for many years. CFPP is a fairly complicated test involving using a vacuum to draw a sample of fuel through a 45 um (micron) screen within a given period of time.

When the HSD and LSD were most prevalent and most fuel filters were 10 um there was a good correlation between CFPP and the temperature at which a standard fuel filter would plug. For example you could be relatively certain that a fuel testing for CFPP of -25°F would provide trouble free operation to -15°F to -20°F.

However the relationship is much different with ULSD. A ULSD fuel testing
-25°F CFPP might have filter plugging problems at between -5°F and -10°F. Also CFPP does not seem to be directly related to Wax Dropout. A fuel can test for
-15°F and still have Wax Dropout at 8°F.

Furthermore, OEM engine manufacturers have changed the media size of their fuel filters. Where 10 um has been almost an industry standard, we now see 7 um, 5 um, and even 2 um filters today. This throws the whole relationship between CFPP and winter operability out the window. For example fuel that is at the CP can have filter plugging problems with a 2 um fuel filter.

The industry has not yet agreed on or developed testing methods to measure cold weather operability with the new fuels and filters.

Until such time as the industry develops a test method for determining the relationship between CFPP, PP, Wax Dropout, and filter media size for ULSD, we suggest the following: For 10 um filters; Take the midpoint between PP and CFPP, for 7 um filters, take the midpoint between PP and CFPP, then take the midpoint between that number and the original CP, for 5 um and 2 um use the CP.

Water is more of a problem than ever before. Diesel and biodiesel fuels hold
water dissolved in them. The amount of water that ULSD is able to hold is greater than that of HSD or LSD. One of the characteristics of fuel is that its ability to hold water in solution diminishes as the temperature decreases. Fuel delivered at 70°F with 200 ppm of dissolved water will as the temperature drops begin to push that water out of the fuel into droplets. These droplets can be seen floating in the fuel and as temperatures reach and go below 32°F those droplets freeze becoming ice crystals.

As a result many of the cold weather problems where people believe they have fuel gelling problem are actually a fuel icing problem. If you have operability issues in temperatures above 0°F you should check to be sure that you aren’t dealing with ice.

Customers are regularly reporting situations where they have no water in storage tanks, no water in vehicle or equipment tanks, but they constantly have water in filters and separators. This is due to the dissolved water falling out of solution due to temperature changes.

Long Term Fuel Storage

Long Term Fuel Storage

STORAGE LIFE

Under normal storage conditions diesel fuel can be expected to stay in a useable condition for:

9-12 months or longer at an ambient of 70ºF.

6-12 months at an ambient temperature higher than 85ºF.

Note: There are many factors that will affect storage life, including but not limited to:

· Ambient temperature

· Temperature variation - the wider the range, the more likely you are to have problems

· Above-Ground versus In-Ground Storage

· Dissolved water content of the fuel

· Humidity

· Quality of the fuel when added to tank

· Condition of storage tank

· Materials used in the tank and fuel piping system

As diesel gets older, fine sediment and gums will form in the fuel brought about by a chemical reaction between components in the diesel fuel with oxygen from the air. The fine sediment and gums can block fuel filters, leading to fuel starvation and the engine stopping. Frequent filter changes are then required to keep the engine going. The gums and sediments do not burn completely in the engine and this incomplete combustion can lead to carbon and soot deposits on injectors and other combustion surfaces.

The expected life of a diesel fuel can be indicated by the oxidation stability test ASTM D2276. The test measures how much gum and sediment will be deposited after keeping the fuel at 120°C in the presence of oxygen for 16 hours. It roughly corresponds to one year storage at 25°C. A result of less than 20mg/L of sediment and gum after the test is considered acceptable for normal diesel.


ACCELERATED AGING

The aging process can be accelerated by the following conditions:

• Contact with zinc, copper or metal alloys containing them. These metals will quickly react with diesel fuel to form unstable compounds.

• The presence of water. Water allows the growth of fungus and bacteria, these produce natural by-products such as organic acids which make the fuel unstable.

• Exposure to high temperatures.

• Exposure to dust and dirt which contain trace elements that can destabilize the fuel, such as copper and zinc.

• Fuel composition. Some components in diesel fuel naturally age quickly.


PROLONGING THE STORAGE LIFE

Prolonging the storage life is achieved by removing or controlling the conditions described in the previous section. Important measures to take are as follows:

• Ensure that the fuel is not in contact with any surfaces containing zinc or copper or compounds containing those metals (e.g. brass). If those metals are present then a metal deactivator additive may help.

• Establish a regular fuel maintenance program to ensure that water and dirt is removed from storage tanks. This will also remove any chance for fungus to grow.

• Water should be drained from the storage tanks weekly. The frequency can be extended if the tank shows no tendency to collect water but should be done at least monthly.

• Tanks should be kept full to reduce the space for water to condense, maintaining tanks half full increases the water build up and promotes corrosion in the top half of the tank. Most water will come from condensation as the tank breathes. The rate at which water collects will depend on local climate and will be higher in hot humid coastal areas.

• Tanks if possible should have a well defined low point where water will collect and can be drained. For example, cone down bottoms.

• Establish a system for filtering the contents of the main storage tank through a recirculating filter system. This can be made automatic and will reduce the potential for problems by removing sediment and gums. The filters should be checked and changed at regular intervals. When the filter change interval reaches a certain frequency then the fuel should be changed over.

• Tanks should be emptied and cleaned at least once every 10 years, or more frequently if there is a major contamination.

• Ensure that the fuel supplied conforms to a recognized specification to ensure the fuel matches the winter cloud point for the area to avoid filter blocking by wax drop out in cold weather.

• Always purchase fuel to replenish stocks in the winter season November - March. This will help to ensure that the fuel will not cause wax problems whatever season it is used.

• Obtain assurances from the supplier that all components are fully refined to promote stability.

• Establish a monitoring program whereby samples are taken at regular intervals to monitor the condition of the fuel. The samples can be examined at the site visually for evidence of haziness, sediment, darkening or sent to a laboratory for testing.

• Regularly turn the fuel over. If possible, plan the fuel usage so that it will all be used within 1-5 years and replaced with fresh fuel.


ADDITIVES TO IMPROVE STORAGE LIFE

The following additives can improve fuel storage life:

• Metal deactivators. These work by stopping copper, zinc and other reactive metals from reacting with the fuel.

• Fungicides/Biocides. These work by stopping fungus and bacteria from growing in the fuel and so prolong the life of the fuel. They are only effective on fungus and bacteria and will not stop other oxidation reactions from taking place. They are normally active at the water fuel interface where the fungus and bacteria grow. If fungus is present then a kill dose is required. Otherwise a maintenance dose is used to stop fungus growing.

The disadvantages of biocides are:

• Handling and mixing is hazardous because they are poisons.

• When using a kill dose, it is important to remember that killing the fungus can lead to a buildup of dead matter which will block filters and also cause the fuel to oxidize.

• Ideally, the fungus should be killed and then the tank emptied and drained out.

• Maintenance doses are effective but no more so than regular water draining and or the use of a Water Dispersant.

• Disposal of water bottoms requires special handling with due regard to the environment.

• Anti-Oxidants. These work by stopping the oxidation processes from taking place. They prevent the fuel oxidizing and reduce the formation of sediment and gum.

As always, your questions and comments are welcomed and encouraged

Fuel and Water - They Don't Go Together

Fuel and Water

They don't mix and you shouldn't try to make them.

One of the more interesting characteristics that is shared by diesel, biodiesel, gasoline, and gasohol is that all these fuels are hygroscopic.

Hygroscopy is the ability of a substance to attract water molecules from the surrounding environment through either absorption or adsorption.

Some examples of this phenomenon are that Ultra-Low Sulfur Diesel (ULSD) will hold approximately 2/10 of 1% dissolved water. This may not sound like much, but if you do the numbers they show that 2/10 of 1% equals 2 gallons of water dissolved in 1000 gallons of fuel. If you work backwards, that would equal 1 gallon of water in 500 gallons of fuel, or 1 quart (32 ozs.), in 125 gallons, or 1 pint (16 ozs.), in 62.5 gallons, down to about 8 ozs. in a 30 gallon tank.

That much water can cause severe corrosion of fuel system components such as injectors, pumps, connectors, and even metal fuel tanks.

That level of water speeds the oxidation and chemical breakdown of the fuel.

That level of water is enough to encourage the growth of bacteria and fungi.

One of the most insidious characteristics of water dissolved in fuel is that the fuels ability to hold water is dependent on temperature. Simply put the warmer the fuel (up to a point) the more water it hold.

What often happens is that fuel stored for example at 60°F will absorb that 2/10% water then as the fuel in a vehicle gets colder more and more of that water is pushed out of the fuel becoming liquid water droplets.

These droplets can collect in filters and if the temperature drops below 32°F those droplets turn to ice crystals quickly plugging filters and causing other problems.

Fuel at 28°F can hold approximately 1/2 as much water as fuel at 60°F.

This means that you can have clear fuel with no liquid water at 60°F and if the temperature drops sufficiently, you can have large amounts of free water suddenly appear as the temperature drops.

To make matters worse biodiesel can pickup and hold 10 times as much water as ULSD. So adding 2% or 5% biodiesel to regular diesel can dramatically increase the level of dissolved water.

Gasoline containing Ethanol suffers the same problem.

A 10% Ethanol blend can hold 3.8 teaspoons of dissolved water at 60°F.

However if more water is added or if the temperature drops significantly this fuel suffers a problem called "Phase Separation".

In Phase Separation the dissolved (or liquid) water binds to the Ethanol and this Water/Ethanol mixture will drop out of the fuel.

This has a series of negative affects on the fuel quality and can have catastrophic effects on engines.

We will discuss more about this later.

We look forward to your comments and questions.

Cold Filter Plug Point versus Cloud Point

CFPP (Cold Filter Plug Point) vs. CP (Cloud Point)
Cold Weather Operability in Diesel Fuels including ULSD

Traditionally the two main considerations for diesel fuel have been Cloud Point (CP) and Cold Filter Plug Point (CFPP).

Let’s start by defining the terms:

Cloud Point (CP) ASTM D2500 – This test determines the point where wax becomes visible in a fuel sample. This wax first appears as a floating cloudiness in a transparent fuel.

Cold Filter Plug Point (CFPP) ASTM D6371 – This test is a more complicated procedure involving using a vacuum to draw a 20cc fuel sample through a 45 micron screen within a 60 seconds.

There is usually but not always a spread between CP and CFPP of 2°F to 8°F.

CP is a first indicator of cold weather operability temperatures for diesel fuels. It is a visible indication of paraffin wax in diesel fuels. Prior to the introduction of Ultra-Low Sulfur Diesel (ULSD, S-15) into the US market, the importance of CP was often discounted by many due to fact that diesel engines could generally successfully operate at temperatures many degrees below the CP.

Up until the introduction of ULSD many if not most operators used CFPP to provide a reference temperature for cold weather operability with diesel fuels. This is however a complicated and imperfect test. As mentioned above, CFPP uses a vacuum to draw a sample of the fuel through a 45 micron screen within a given time. The point at which the sample fails to go through the screen in 60 seconds is the CFPP.

The main issue is that up until recently most fuel filters used a 10 micron filtering media. The significant difference 10 microns and 45 microns caused a disparity between the test and real world operations. However many in the industry felt that this differential was consistent and that provided a reliable guide for cold weather operability.

For example if you had a CFPP of -30°F, you could feel reasonably confident that you could operate to -20°F.

However three new factors need to taken into account due to changes in fuels and engines.

1. The new ULSD fuel does not appear to provide the same consistent differential between CP and CFPP as we had come to expect with High-Sulfur Diesel (HSD, S-5000) and Low-Sulfur Diesel (LSD, S-500).

2. The new phenomenon of Wax Drop Out (WDO) where under periods of extended “Cold Soak” (48-72+ hours) the wax in the fuel suddenly drops out of the fuel can happen at temperatures that can be above the CP. This problem appears at this time to be independent of CP or CFPP.

3. As diesel engines have become more sophisticated there has been a rise in fuel injection pressures. In order to obtain these higher pressures OEM’s have had to manufacture pump and injector parts to ever closer tolerances. Today many injectors have tolerances in the 2 micron range. These tight tolerances and the very high cost of making and replacing these components have caused manufacturers to use fuel filters with smaller media to protect these components. Where in the past fuel filters typically were 10 microns, today we are seeing filters of 7, 5, and even 2 microns.

This makes the problems associated with ULSD even more difficult. Cloudy fuel that would easily pass through a 10 micron filter can often plug a 5 or 2 micron filter. This makes correcting the cold weather operability issues of ULSD like hitting a moving target. Today you need to adjust your fuel treatment to reflect the engines and filter arrangements in your fleet.

We are now suggesting a formula based on both CP and CFPP. Take the difference between CP and CFPP, divide by 1.5 and add to the CFPP to get a safe operability number.

Example: CP = 8°F, CFPP = 3°F

The difference between 8 and 3 = 5, 5 x .75 = 3.75, Take the CFPP of 3 and add the 3.75 to it equaling 6.75°F. You could expect to reliably operate that fuel in an engine with a 7 to 5 micron filter at 6-7°F.

For those operating 2 micron filters we suggest using the CP of the fuel.

For those still able to operate with 10+ micron filters, we are suggesting a number half way between CP and CFPP.

It is important to remember that the traditional method of using Kerosene or Jet A to “cut” or blend with HSD or LSD to lower the CFPP and Pour Point (PP) is not as effective or reliable as it was in the past when using the new ULSD #1 to cut or blend with ULSD #2.

Winter Problems with Ultra-Low Sulfur Diesel (ULSD)

Winter Problems with Ultra-Low Sulfur Diesel (ULSD)

Which One of these Filters Would You Rather Have on Your Vehicle?

The above image is from February 5th 2007, the first real winter weather while using the “new” Ultra Low Sulfur Diesel (ULSD). After being told by refiners and many distributors that ULSD would be the “be all, end all” magic problem solver for all diesel engines, this is what really happened when it finally got cold and stayed cold for 48+ hours.

The red colored filter on the left is the result of a fuel distributor using so much anti-gel additive that it actually saturated the fuel to the point of completely plugging THOUSANDS of fuel filters over several days.

The filter on the right shows paraffin wax plugging it. This customer used ULSD #1 (ULSD Kerosene) to “cut” the ULSD #2 fuel. However the “new” ULSD #1 doesn’t work the same way as the “old” LSD Kerosene (see more below)

The new ULSD gels 4°F to 5°F sooner than the “old” Low Sulfur Diesel (LSD). The new ULSD is harder to treat for cold weather than the “old” LSD. Many additives that you have been using for years no longer work on the “new” ULSD. The “new” ULSD holds more dissolved water than the “old” LSD, causing ice formation as the temperature drops below freezing.

When treating with a cold flow improver (anti-gel), using the recommended treatment ratio provides a certain level of protection, using twice the recommended ratio may improve the gel point a little, however if you go beyond that level it will actually raise or worsen the gel-point. At treatment levels beyond 3-4 times the recommended ratio, you will begin to saturate the fuel and can actually plug a filter full of anti-gel additive. This is generally indicated by a reddish or pink colored wax-like substance covering the filter as much as ¼” thick. This wax-like substance will not readily melt at room temperature unlike paraffin wax that melts above 32°F.

In the past the general “Rule of Thumb” regarding using Kerosene (#1D) to “cut” #2 diesel was that for every 10% kerosene added to #2 diesel you would lower the Cold Filter Plug Point (CFPP) by approximately 5°F. So for example a 50%-50% blend of #2D and Kerosene would have lowered CFPP by approximately 25°F. The “new” ULSD #1 is far less aromatic and has much less solvency than did the old Kerosene. As a result the new ULSD #1 will only lower CFPP by 2°F-3°F. This means that a 50%-50% blend will only lower CFPP by 10°F to maybe 15°F.

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Doctor Diesel