September 25, 2024 • 12 mins
In this episode of the Fuel Pulse Show podcast, host Erik Bjornstad explores diesel fuel's behavior in cold temperatures. He explains the fuel's composition, focusing on paraffin wax molecules and their role in cold weather problems.
The episode covers key concepts such as cloud point and cold filter plug point, detailing how paraffin wax crystallization occurs and affects fuel performance. Bjornstad provides typical temperature ranges for these phenomena and discusses factors influencing fuel gelling. The episode concludes with a preview of future content on temperature patterns and prevention strategies for cold weather fuel issues.
What You'll Learn:
- The composition of diesel fuel and the role of paraffin wax molecules
- How temperature affects the solubility of paraffin wax in diesel fuel
- The concept of cloud point and its typical temperature range
- The process of wax crystallization and its impact on fuel performance
- The definition and importance of cold filter plug point
- Factors influencing the difference between cloud point and cold filter plug point
- Why gasoline and kerosene don't have the same gelling problems as diesel fuel
Ideas Worth Sharing:
Here are three notable quotes from the podcast episode:
- "Diesel fuel is actually a mixture or a blend of a bunch of different petroleum hydrocarbon molecules of varying sizes and shapes."
- "The temperature at which enough of these crystals have come out of solution that you can see them in the fuel, that is called the cloud point of the fuel."
- "Cold filter plug point temperature, when you're looking at that, it's not just the fuel, you've also got the factor of the filter that's involved."
Resources:
- Erik Bjornstad: LinkedIn
Show Notes:
[00:00:00] Introduction to the episode's topic: What happens to diesel fuel in cold temperatures
[00:01:00] Explanation of diesel fuel composition and paraffin wax
[00:02:00] Discussion of how paraffin wax becomes insoluble as fuel cools
[00:03:00] Introduction to the concept of cloud point
[00:04:00] Typical cloud point temperature for ultra-low sulfur diesel fuel
[00:05:00] Explanation of wax crystallization process as temperature drops
[00:06:00] Discussion of what happens when temperature stays cold or drops further
[00:07:00] Explanation of how wax buildup affects fuel filters and engine operation
[00:08:00] Introduction to cold filter plug point temperature
[00:09:00] Comparison of cloud point and cold filter plug point temperatures
[00:10:00] Recap of key points learned about diesel fuel in cold temperatures
[00:11:00] Preview of next episode's content
[00:12:00] Closing remarks and call to action for listeners
Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
(00:00):
Welcome to the Fuel Pulse Showpodcast, where we talk about all
things fuel for all kinds of people.
I'm your host, Eric Bjornstad,and I will be your guide through
the ever changing world of fuel.
Today, we're doing one of ourFuel Pulse show back to school
episodes, where we go back to thebasic building blocks of fuel care.
(00:21):
Now, today, we're talking aboutwhat happens to diesel fuel
when the temperatures get cold.
That means We're going to cover areasthat we need to understand better if we're
going to get a better handle on how allof this stuff works, which means we have
to talk about what the fuel is made of.
We want to talk about what happenswhen the fuel gets cold and.
(00:45):
We have to talk about how do you knowwhen the temperature is low enough that
it's going to cause a problem or beexpected to cause a problem with the fuel.
So diesel fuel is actually a mixtureor a blend of a bunch of different
Petroleum hydrocarbon moleculesof varying sizes and shapes.
(01:07):
Some of them are long and longerstraight chain hydrocarbons.
Some of them are chain hydrocarbonsthat have lots of branches and
functional groups coming off of them.
Some of them are cyclical.
Some of them arecombinations of all these.
Some of these molecules that makeup the diesel fuel composition
are also known as paraffin.
(01:29):
So you're going to wantto remember that term.
Now one principle that's often trueis when a liquid cools down, its
ability to dissolve and to hold onto dissolved things can be reduced.
I mean, think about it.
It's harder for cold liquids todissolve you know, any number of things.
(01:51):
Kind of like if you try tomix sugar in with cold tea.
And it's also true that for manykinds of liquids that have components
dissolved in them, it's harder forthem to hold on to those things.
As their temperature drops, and thisis what happens with diesel fuel.
At normal temperatures, those paraffin waxmolecules, they're dissolved in the fuel.
(02:12):
They're burned as part ofthe fuel's composition.
Yet, all diesel fuelshave a temperature point.
Where if the temperature dropsbelow that point, the paraffin waxes
aren't going to be able to stay.
So they'll become insoluble,and they'll start to come out
of solution as crystals of wax.
(02:34):
Now they don't all come out at once,it depends on the sizes of molecules
as to which ones come out first.
So, as the fuel gets cold, theinitial, the first paraffin wax
molecules that are the leastsoluble, they come out of the fuel.
Now, at this point, you're not goingto see them, but they're coming out
of the fuel as these little crystals.
(02:55):
But, as the fuel stays cold, or maybeit gets even colder, more and more
of them do exactly the same thing.
They continue to drop out of the fuel.
So, you've got the ones thatcame out first, they're in there.
Then, as time goes on, you've got moreand more of them coming out to join them.
When enough of these crystals have comeout of solution, you may even be able to
(03:19):
see the fuel take on a slight haze or acloudiness, and that will increase as more
and more of the paraffins keep coming up.
So, the temperature point at which enoughof these Come out of solution that you can
see them in the fuel that is called thecloud point of the fuel And it's the first
(03:40):
important temperature spec that's usefulto know about the fuel that you have
now What's the common cloudpoint temperature for ultra
low sulfur diesel fuel?
Well before we can answer that question Wefirst have to acknowledge that all fuels
are actually different The cloud pointtemperature for your fuel in your storage
tank May not be exactly the same as thediesel fuel down the road because diesel
(04:05):
fuels refined from a natural product.
Petroleum oil, right?
So the exact characteristics foreach batch of diesel fuel might vary
a little bit, especially when itcomes to the thing that most directly
impacts how fuel And when the waxcomes out in the cold temperatures.
And that is the number andthe sizes of the paraffin wax
(04:29):
molecules in the diesel fuel.
What they call the wax distribution.
But getting into the vagariesof that is probably a level of
detail that requires another show.
But just keep that principle in mind.
, back to the question.
What's a common cloud pointtemperature for diesel fuel?
If we have to give a general answer,They tend to find that a good
cloud point Typical cloud point isaround 16 to 17 degrees Fahrenheit.
(04:54):
Now there is some difference incloud one temperature for summer
diesel versus winter diesel.
But chances are, if you have storeddiesel fuel that has been around
for a while, you've probably gota combination of those anyway.
So I usually settle on 16or 17 degrees Fahrenheit.
Remember though, Cloud point isthe temperature at which you've got
(05:16):
enough wax that's come out of thefuel that you can see it clouding up.
The thing you have to remember is,cloud point isn't the temperature at
which the wax first starts to drop out.
The wax has actually been starting to dropout at x degrees above that cloud point.
Now, Let's consider a weatherscenario and we're going to consider
(05:38):
two possibilities in that scenario.
So let's say you'vegot some stored diesel.
Let's say that a coldfront's coming through.
So the temperature's droppingand the temperature gets down
to 19 degrees Fahrenheit.
And so some of the wax is coming out orit's already come out of your stored fuel.
(05:59):
Now, the weather can do one of two things.
It can either warm back up, orit can stay at, or even drop
further below the cloud point.
In other words, it can staycold, or maybe even get colder.
If the temperature warms back up, thatwax that came out, It's simply going
(06:21):
to re dissolve back into the fuel.
And you're going to be fine, becausethat kind of cycle happens all the time.
The wax drops out, thingswarm up, the wax re dissolves.
Pretty common.
But, what happens ifthat isn't what happens?
What happens if it stayscold, or gets even colder?
Well, then what you're going to see there,is you're going to keep having more wax
(06:42):
crystals coming out, joining those thatare already in the fuel, of course.
And so what's going to happen is, thosewax crystals, they're inevitably going
to They're going to bump into eachother, and as they bump into each other,
they're going to stick together, andso they're going to grow bigger, and
then they're going to bump into more,they're going to grow bigger, and so
this wax content, these crystals aregoing to keep getting bigger and bigger
(07:04):
and bigger, and over time, if enoughof them come out, what may even happen
is you might get almost a web of waxthat's forming in the fuel, trapping
fuel, in between all the strands.
And practically what happens is thefuel starts to thicken, as you may
expect, when you reach that point inthe fuel, there's going to be plenty
(07:27):
of wax in the fuel that's goingto get caught by the fuel filter.
As time goes on, that fuel filter isgoing to trap more and more of that
paraffin, which means less and less fuelcan actually get through that fuel filter.
And there will come a point.
Where sufficient fuel, the problem'sbad enough that sufficient fuel won't be
(07:50):
able to get through to keep the enginerunning and the engine then shuts down
because of insufficient fuel flow.
Now as an aside, now that we know theroot causes of fuel gelling, you know, wax
composition, we can now know why gasolineand kerosene don't have the same kind of
gelling problems that number two dieselfuel have because they don't have enough
(08:13):
paraffin content for it to be an issue.
The temperature at which this wholething happens, the temperature at which
there's enough wax in there that thefuel filter is getting plugged with wax
and the engine is shutting down, thatis the second important temperature.
That's commonly known asthe cold filter plug point.
Temperature.
(08:33):
The temperature at which the fuelthickens enough to plug the fuel
filter and stop the fuel flow.
And really that's the temperaturethat you're most concerned with.
What temperature is low enough so thatenough wax will have dropped out of my
fuel to plug my fuel filter and shutdown operation in the cold weather.
So if you were gonna pick atemperature to use as a benchmark
(08:54):
for action, you would think that youwould pick cold filter plug point.
However, as we'll explain here shortly, itmight not actually be quite that simple.
So, go back to CloudPoint.
If the 17 degrees, what's goingto be the cold filter plug point?
Now we go back to it depends.
(09:16):
And you know, my favoriteanswer, the it depends answer.
Now, cold filter plug points alwaysgoing to be lower than CloudPoint.
The question is, how much lower?
Well, consider that cloudpoint temperature is, it
really is fuel dependent.
It depends almost entirely on thecharacteristics of the fuel in terms
(09:37):
of the wax size distribution in thefuel, and how the outside temperature
patterns affect that wax's solubility.
Cold filter plug point's different though.
Cold filter plug point temperature,when you're looking at that, it's not
just the fuel, you've also got thefactor of the filter that's involved.
(09:58):
We see this with commonrail diesel engines.
They tend to use high performancefuel filters, and high performance
fuel filters plug more easily.
So the difference between the cloudpoint and the coal filter plug
point actually turns out to besmaller, narrower than it used to be.
Now a good benchmark is there'sabout a three to five degrees
(10:20):
difference between the cloud pointand the plug point temperatures.
And so that is a pretty goodstopping point for today.
What have we learned?
Well, we learned that numbertwo diesel fuel has heat.
paraffin wax in it.
And this wax is normally dissolved, butit can become insoluble and it can drop
(10:41):
out as temperatures get cold enough.
The temperature at which enoughof that wax drops out that it
turns the fuel cloudy, that'sthe cloud point of the fuel.
If the temperature drops far enoughbelow the cloud point, eventually,
Enough of the wax is going to come outof that fuel that it's going to thicken
the fuel, it's going to get caughtin the fuel filter, interrupting the
(11:02):
fuel flow, causing operation shutdown.
The temperature at whichthat's most likely to happen
is the cold filter plug point.
A typical cloud point for dieselfuel is about 16 to 17 degrees.
Typical plug point is about 3to 5 degrees colder than that.
But, last point, even those principleshave exceptions because We haven't
(11:25):
even considered how temperaturepatterns, how long it stays cold,
whether it gets cold gradually or not.
We haven't even considered howthose kind of temperature patterns
can influence how and when coldweather fuel problems appear.
So we're going to talkabout that in more detail.
along with the kinds of options thatwe do have for preventing these kinds
(11:47):
of problems in our next episode.
So, thanks for joining me today.
If you liked what you heard, andyou haven't done so already, feel
free to subscribe at your podcastplatform of choice, whether it's
iTunes, Stitcher, Google Podcasts, orwherever you happen to like to listen.
And, leave us a review if youcan, because that really does
help other people find us.
(12:08):
So, until next time, I'm EricBjornstedt, thanking you for joining
us, and we'll see you next timeat the Field Poll Show Podcast.
Welcome to the Fuel Pulse Showpodcast, where we talk about all
things fuel for all kinds of people.
I'm your host, Eric Bjornstad,and I will be your guide through
the ever changing world of fuel.
Today, we're doing one of ourFuel Pulse show back to school
episodes, where we go back to thebasic building blocks of fuel care.
(00:21):
Now, today, we're talking aboutwhat happens to diesel fuel
when the temperatures get cold.
That means We're going to cover areasthat we need to understand better if we're
going to get a better handle on how allof this stuff works, which means we have
to talk about what the fuel is made of.
We want to talk about what happenswhen the fuel gets cold and.
(00:45):
We have to talk about how do you knowwhen the temperature is low enough that
it's going to cause a problem or beexpected to cause a problem with the fuel.
So diesel fuel is actually a mixtureor a blend of a bunch of different
Petroleum hydrocarbon moleculesof varying sizes and shapes.
(01:07):
Some of them are long and longerstraight chain hydrocarbons.
Some of them are chain hydrocarbonsthat have lots of branches and
functional groups coming off of them.
Some of them are cyclical.
Some of them arecombinations of all these.
Some of these molecules that makeup the diesel fuel composition
are also known as paraffin.
(01:29):
So you're going to wantto remember that term.
Now one principle that's often trueis when a liquid cools down, its
ability to dissolve and to hold onto dissolved things can be reduced.
I mean, think about it.
It's harder for cold liquids todissolve you know, any number of things.
(01:51):
Kind of like if you try tomix sugar in with cold tea.
And it's also true that for manykinds of liquids that have components
dissolved in them, it's harder forthem to hold on to those things.
As their temperature drops, and thisis what happens with diesel fuel.
At normal temperatures, those paraffin waxmolecules, they're dissolved in the fuel.
(02:12):
They're burned as part ofthe fuel's composition.
Yet, all diesel fuelshave a temperature point.
Where if the temperature dropsbelow that point, the paraffin waxes
aren't going to be able to stay.
So they'll become insoluble,and they'll start to come out
of solution as crystals of wax.
(02:34):
Now they don't all come out at once,it depends on the sizes of molecules
as to which ones come out first.
So, as the fuel gets cold, theinitial, the first paraffin wax
molecules that are the leastsoluble, they come out of the fuel.
Now, at this point, you're not goingto see them, but they're coming out
of the fuel as these little crystals.
(02:55):
But, as the fuel stays cold, or maybeit gets even colder, more and more
of them do exactly the same thing.
They continue to drop out of the fuel.
So, you've got the ones thatcame out first, they're in there.
Then, as time goes on, you've got moreand more of them coming out to join them.
When enough of these crystals have comeout of solution, you may even be able to
(03:19):
see the fuel take on a slight haze or acloudiness, and that will increase as more
and more of the paraffins keep coming up.
So, the temperature point at which enoughof these Come out of solution that you can
see them in the fuel that is called thecloud point of the fuel And it's the first
(03:40):
important temperature spec that's usefulto know about the fuel that you have
now What's the common cloudpoint temperature for ultra
low sulfur diesel fuel?
Well before we can answer that question Wefirst have to acknowledge that all fuels
are actually different The cloud pointtemperature for your fuel in your storage
tank May not be exactly the same as thediesel fuel down the road because diesel
(04:05):
fuels refined from a natural product.
Petroleum oil, right?
So the exact characteristics foreach batch of diesel fuel might vary
a little bit, especially when itcomes to the thing that most directly
impacts how fuel And when the waxcomes out in the cold temperatures.
And that is the number andthe sizes of the paraffin wax
(04:29):
molecules in the diesel fuel.
What they call the wax distribution.
But getting into the vagariesof that is probably a level of
detail that requires another show.
But just keep that principle in mind.
, back to the question.
What's a common cloud pointtemperature for diesel fuel?
If we have to give a general answer,They tend to find that a good
cloud point Typical cloud point isaround 16 to 17 degrees Fahrenheit.
(04:54):
Now there is some difference incloud one temperature for summer
diesel versus winter diesel.
But chances are, if you have storeddiesel fuel that has been around
for a while, you've probably gota combination of those anyway.
So I usually settle on 16or 17 degrees Fahrenheit.
Remember though, Cloud point isthe temperature at which you've got
(05:16):
enough wax that's come out of thefuel that you can see it clouding up.
The thing you have to remember is,cloud point isn't the temperature at
which the wax first starts to drop out.
The wax has actually been starting to dropout at x degrees above that cloud point.
Now, Let's consider a weatherscenario and we're going to consider
(05:38):
two possibilities in that scenario.
So let's say you'vegot some stored diesel.
Let's say that a coldfront's coming through.
So the temperature's droppingand the temperature gets down
to 19 degrees Fahrenheit.
And so some of the wax is coming out orit's already come out of your stored fuel.
(05:59):
Now, the weather can do one of two things.
It can either warm back up, orit can stay at, or even drop
further below the cloud point.
In other words, it can staycold, or maybe even get colder.
If the temperature warms back up, thatwax that came out, It's simply going
(06:21):
to re dissolve back into the fuel.
And you're going to be fine, becausethat kind of cycle happens all the time.
The wax drops out, thingswarm up, the wax re dissolves.
Pretty common.
But, what happens ifthat isn't what happens?
What happens if it stayscold, or gets even colder?
Well, then what you're going to see there,is you're going to keep having more wax
(06:42):
crystals coming out, joining those thatare already in the fuel, of course.
And so what's going to happen is, thosewax crystals, they're inevitably going
to They're going to bump into eachother, and as they bump into each other,
they're going to stick together, andso they're going to grow bigger, and
then they're going to bump into more,they're going to grow bigger, and so
this wax content, these crystals aregoing to keep getting bigger and bigger
(07:04):
and bigger, and over time, if enoughof them come out, what may even happen
is you might get almost a web of waxthat's forming in the fuel, trapping
fuel, in between all the strands.
And practically what happens is thefuel starts to thicken, as you may
expect, when you reach that point inthe fuel, there's going to be plenty
(07:27):
of wax in the fuel that's goingto get caught by the fuel filter.
As time goes on, that fuel filter isgoing to trap more and more of that
paraffin, which means less and less fuelcan actually get through that fuel filter.
And there will come a point.
Where sufficient fuel, the problem'sbad enough that sufficient fuel won't be
(07:50):
able to get through to keep the enginerunning and the engine then shuts down
because of insufficient fuel flow.
Now as an aside, now that we know theroot causes of fuel gelling, you know, wax
composition, we can now know why gasolineand kerosene don't have the same kind of
gelling problems that number two dieselfuel have because they don't have enough
(08:13):
paraffin content for it to be an issue.
The temperature at which this wholething happens, the temperature at which
there's enough wax in there that thefuel filter is getting plugged with wax
and the engine is shutting down, thatis the second important temperature.
That's commonly known asthe cold filter plug point.
Temperature.
(08:33):
The temperature at which the fuelthickens enough to plug the fuel
filter and stop the fuel flow.
And really that's the temperaturethat you're most concerned with.
What temperature is low enough so thatenough wax will have dropped out of my
fuel to plug my fuel filter and shutdown operation in the cold weather.
So if you were gonna pick atemperature to use as a benchmark
(08:54):
for action, you would think that youwould pick cold filter plug point.
However, as we'll explain here shortly, itmight not actually be quite that simple.
So, go back to CloudPoint.
If the 17 degrees, what's goingto be the cold filter plug point?
Now we go back to it depends.
(09:16):
And you know, my favoriteanswer, the it depends answer.
Now, cold filter plug points alwaysgoing to be lower than CloudPoint.
The question is, how much lower?
Well, consider that cloudpoint temperature is, it
really is fuel dependent.
It depends almost entirely on thecharacteristics of the fuel in terms
(09:37):
of the wax size distribution in thefuel, and how the outside temperature
patterns affect that wax's solubility.
Cold filter plug point's different though.
Cold filter plug point temperature,when you're looking at that, it's not
just the fuel, you've also got thefactor of the filter that's involved.
(09:58):
We see this with commonrail diesel engines.
They tend to use high performancefuel filters, and high performance
fuel filters plug more easily.
So the difference between the cloudpoint and the coal filter plug
point actually turns out to besmaller, narrower than it used to be.
Now a good benchmark is there'sabout a three to five degrees
(10:20):
difference between the cloud pointand the plug point temperatures.
And so that is a pretty goodstopping point for today.
What have we learned?
Well, we learned that numbertwo diesel fuel has heat.
paraffin wax in it.
And this wax is normally dissolved, butit can become insoluble and it can drop
(10:41):
out as temperatures get cold enough.
The temperature at which enoughof that wax drops out that it
turns the fuel cloudy, that'sthe cloud point of the fuel.
If the temperature drops far enoughbelow the cloud point, eventually,
Enough of the wax is going to come outof that fuel that it's going to thicken
the fuel, it's going to get caughtin the fuel filter, interrupting the
(11:02):
fuel flow, causing operation shutdown.
The temperature at whichthat's most likely to happen
is the cold filter plug point.
A typical cloud point for dieselfuel is about 16 to 17 degrees.
Typical plug point is about 3to 5 degrees colder than that.
But, last point, even those principleshave exceptions because We haven't
(11:25):
even considered how temperaturepatterns, how long it stays cold,
whether it gets cold gradually or not.
We haven't even considered howthose kind of temperature patterns
can influence how and when coldweather fuel problems appear.
So we're going to talkabout that in more detail.
along with the kinds of options thatwe do have for preventing these kinds
(11:47):
of problems in our next episode.
So, thanks for joining me today.
If you liked what you heard, andyou haven't done so already, feel
free to subscribe at your podcastplatform of choice, whether it's
iTunes, Stitcher, Google Podcasts, orwherever you happen to like to listen.
And, leave us a review if youcan, because that really does
help other people find us.
(12:08):
So, until next time, I'm EricBjornstedt, thanking you for joining
us, and we'll see you next timeat the Field Poll Show Podcast.
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