When it comes to efficiency and range of performance, nothing comes close to diesel fuel. Truck drivers and off-road enthusiasts prefer this type of fuel not only because of its fuel efficiency, but it also gives engines ample power as compared to petrol or gasoline.
These benefits are just one of the many characteristics that set diesel apart from gasoline. Benefits aside, one other aspect of diesel that makes it completely different from gas is its weight. The reason behind that is that diesel has larger molecules than gasoline. In that case, the atomization process for diesel is different because of its high viscosity and density levels.
What’s the Fuss All About? — Determining the Weight of Diesel
Since diesel weighs more than its counterpart, is it important that you determine its actual weight, say, by the gallon? A US gallon of diesel would typically weigh anywhere between 6.82 lbs. and 8 lbs. On the other hand, an imperial gallon would give you around 8.19 to 9.61, while a US dry gallon anywhere from 7.93 to 9.32 lbs. Given the considerable difference in the numbers, it would be wise to stick with the US gallon because it is a widely used international standard of measurement.
Anyway, this inconsistency may have one asking why diesel would act this way, especially to those unfamiliar with the nature of this fuel type. For the sake of uniformity and this article, however, let us opt for 7 lbs. per gallon of diesel for quicker and easier calculations.
In any case, you should know how much a gallon of diesel weighs because there are several variants of diesel fuel available, and each of which has its own recommended usage. Additionally, numerous other factors can affect the density of diesel.
Why Does It Matter?
Diesel is used mainly in high-torqued transports, such as in trucks and other off-road vehicles. The amount of diesel present inside the tank also affects the weight of a particular vehicle. Large trucks are often subject to weight restrictions. Therefore, truck drivers should consider the weight capacities of the axles, including the overall cargo load. In other words, you should know the actual weight of a gallon of diesel for the sake of practical application.
Let’s consider the fuel tank on a semi-truck located on each side to balance its weight to get a clearer picture. The capacity of each tank averages roughly between 120 and 150 gallons, totalling up to either 240 or 300 US gallons. With that said, the overall weight of the semi’s overall fuel load would range between 1,680 and 2,100 lbs.
Fuel mileage is another factor to consider because the weight of the fuel could increase the drag and affect overall fuel consumption. The amount of diesel in the fuel tank could have a significant output in mileage and fuel economy. In that case, a full tank seems counterintuitive, especially for off-road vehicles. Not only will that have a considerable effect on the fuel budget, but that could also cause engine problems, especially in ATVs or UTVs.
Apart from these examples, transporting diesel fuel from origin to destination also requires careful calculation and consideration concerning the size and capacity of the tanks in a fuel tanker or tankship. A large tanker truck would have an average capacity ranging from approximately 6,000 to over 11,000 US gallons. However, the total amount of diesel it could carry would depend on the density of fuel per gallon.
Factors That Affect the Weight of Diesel
One aspect of diesel that distinguishes the fuel from its counterpart is that its density remains subject to change due to different factors. For this reason, calculating the exact weight of diesel per gallon requires knowledge of the different factors that make diesel’s weight an ever-changing variable.
For instance, the different units used in measuring the density of a liquid—such as kg/L, g/cm3, kg/m3, slugs/ft3, and even lb/ft3, to name a few—may often result in inconsistencies in relation to a gallon of diesel. Currently, we use three: US gallon, imperial gallon, and dry gallon.
This is an aspect that should be taken into account when determining the total density of the fuel by the gallon, to develop a sense of uniformity and determinability at the very least. For that matter, you should take note of the three other factors, which are as follows:
1. Temperature Fluctuations
The change in temperature and humidity affects the total volumetric density of diesel. The same can be said of other compounds and substances, such as engine oil and essential oils. When it comes to diesel fuel, however, the changes are not that significant. Nevertheless, it is still worth noting.
For instance, a gallon of diesel would weigh 6.93 lbs. at 20° C (68° F). If we alter the temperature to 30° C (86° F), that same gallon of diesel fuel would become 6.88 lbs. Interestingly, if we raise the temperature to 45° C (113° F), the weight would plummet down to 6.79 lbs.
With these values, you would immediately notice a pattern here: an increase in temperature causes a slight reduction in the density of diesel fuel. Though the weight change is minimal, it is still worth noting because, in larger quantities, the values would be considerably higher.
2. Fuel Rating
Diesel is graded based on its cetane number, just as gasoline is with its octane rating. Cetane determines the combustion efficiency of a type of diesel fuel. Generally, the diesel fuel with a higher cetane number would have a faster ignition rate and produces more torque and horsepower. With that said, diesel fuel with a higher cetane number (CN) would typically have a relatively higher density. That’s because lower density fuel contains fewer BTUs, which means it will provide less energy to a diesel engine.
3. API Gravity
API gravity is a unit of expression developed by the American Petroleum Institute which measures the weight of a particular liquid relative to the weight of water, similar to specific gravity. With this measurement conversion, we can determine that a substance has less density if it has a high API gravity rate.
This value, alongside specific gravity, is used mainly during the production of crude oil and is a determinant in establishing its trading price. According to www.amspecgroup.com, the typical API gravity of a Number 2 diesel oil ranges between 30 and 40 degrees. If you will use the specific gravity converter at www.engineeringtoolbox.com, the corresponding specific gravity of each value would be 0.8672 and 0.8251. With these values, the weight of diesel would be anywhere from 6.87 to 7.30 lbs./US gallon.
What Are the Different Types of Diesel?
Unlike gasoline, diesel is oil, which means it has varying rates of viscosity. Because of this unique characteristic, this fuel comes with different variants, and each is classified based on its thickness. The different types of diesel fuel are as follows:
- Number 1 Diesel (1-D)
What distinguishes Number 1 diesel or 1-D from the other diesel fuels is that this fuel variant has lower viscosity because of the extraction of paraffin from its chemical composition. Therefore, it flows more fluidly and has less lubricity than its other diesel counterparts, such as 2-D fuel. 1-D fuel also makes an ideal fuel in wintry conditions.
Furthermore, this variant has a high cetane rating, which translates to a high volatility rate, so it has a shorter ignition delay and combusts faster. For that matter, 1-D fuel makes an excellent fuel for off-road vehicles, like tractors, and space heating for houses. As such, 1-D is dyed red, which indicates that this fuel is not road-legal and should not be taxed. In that sense, the colour also sets 1-D apart from regular diesel.
- Number 2 Diesel (2-D)
Unlike Number 1, 2-D is the regular form of diesel fuel and has better lubricity because of its higher viscosity rating, making it the ideal variant in warmer areas of the country. Coupled with its high cetane rating, 2-D has a relatively lower combustion rate as compared to 1-D, which means it is more fuel-efficient.
While 2-D makes a poor fuel substitute in cold weather, its thickness offers better lubricity in areas with warmer climes. In most circumstances, 2-D can be intermixed with 1-D, which gives the latter winter-capable properties. Regardless of this shortcoming, 2-D fuel is more cost-effective than 1-D.
Furthermore, because of the different distillate methods employed in the manufacturing process, not to mention the various diesel engine types available, not all 2-D are created equal. There are several types of 2-D and these are as follows:
o Petroleum diesel
o Biodiesel
o Synthetic diesel
o Dimethyl ether (DME)
o Hydrogenated oils and fats
o Ultra-low sulfur diesel (ULSD)
- Number 4 Diesel (4-D)
This type of diesel fuel is employed mostly in low-speed engines, such as those in power generators and locomotives. 4-D fuel variants are also ideal for marine use and stationary units.
Given the properties of each diesel variant, the 1-D, 2-D, and 4-D fuels would have varying values. According to www.engineeringtoolbox.com, the density of these diesel types at 15° C or 59° F (the temperature in which all diesel fuel types would be in their loose, flowing state) in kilograms per cubic meter and pound per cubic feet are as follows:
o Number 1 (1-D) — 875 kg/m3 or 54.6 lb/ft3
o Number 2 (2-D) — 849 kg/m3 or 53 lb/ft3
o Number 4 (4-D) — 959 kg/m3 or 59.9 lb/ft3
Based on the given values above, the table below shows the difference in weight between the 1-D, 2-D, and 4-D fuels. That we know 1-D is denser than 2-D means that the former should be more volatile than the latter, and the numbers above prove that general fact. Thus, with these values, we can interpret that the denser the diesel fuel, the higher the CN, and that indicates a higher combustibility rate.
| Weight of the Different Diesel Fuel Variants (at 15° C or 59° F) | |||
| Diesel Type | Pound per US gallon(lb/usgal) | Pound per imperial gallon(lb/impgal) | Pound per US dry gallon(lb/usdrygal) |
| Number 1 (1-D) | 7.30 | 8.76 | 8.49 |
| Number 2 (2-D) | 7.09 | 8.51 | 8.24 |
| Number 4 (4-D) | 8.00 | 9.61 | 9.32 |
Final Takeaway — Actual Weight of Diesel
Diesel fuel not only comes in different variants—1-D, 2-D, and 4-D—, but it also comes in varying densities. Likewise, these properties all depend on different factors, which are changes in ambient temperature, cetane rating, and API specific gravity.
Furthermore, given the technicality involved in the process of obtaining the weight of diesel, it is easy for anyone to dismiss the whole concept as a complete waste of time. However, as discussed in this article, understanding what factors affect the overall density of diesel can help anyone, especially with their fuel efficiency and budget for fuel consumption, to name a few.
