MadSci Network: Chemistry

Re: Can JET-A fuel substitute for 1-D or 2-D diesel

Date: Wed Mar 22 13:44:15 2000
Posted By: Joseph Weeks, President, Thermal Products, Inc.
Area of science: Chemistry
ID: 952745334.Ch

Free fuel sounds like a great idea, however there are several matters which 
need to be considered.  First, the fuel at the bottom of the tank probably 
has dirt and other crud which can cause wear of the fuel injection system. 
 Assuming that you eliminate the dirt, then there is the question of 
compatibility.  I contacted Marketing Fuel Technical Service at Chevron 
concerning your question.  Their response is as follows:
"In regards to your inquiry about whether Jet A can be run in a diesel 
engine, Chevron would never advise anyone to use a particular fuel in an 
engine that was not designed for that fuel. We would advise that the 
inquiry be made to the equipment (engine) manufacturer."

Remember, while there is only one basic Jet A species, there are several 
kinds of diesel - diesel No. 1 and diesel No. 2 (amongst others). Jet A is 
more like Diesel No. 1.  Diesel No. 2 is the more common "diesel" fuel, 
since it is the fuel used by vehicles "on-road".

All of the fuels are products of the refining process. One of the main 
differences between them is their distillation boiling ranges. Diesel No. 2 
has a higher (in temperature) boiling range and is more dense than Jet A 
and/or diesel No. 1 (both of which have lower densities and lower
boiling range temperatures). A fuel which is less dense will have lower 
fuel economy (less BTU's per gallon). All of this is "besides the point" as far 
as the appropriateness of any of the three to perform in the engines that were 
designed for their use. If the engine manufacturer indicates the use of only one 
type of fuel, that is the fuel that should be used.
For further information please visit Chevron's INTERNET site at
There are some very informative publications at the site at
on_root/prodserv (there is an "underscore" character after the second 
"chevron" word). When you reach that site, click on the word "Fuels" and you 
will then see a "Publications" option.

That said, we will break down your inquiries into a group of statements 
that we have put together to answer others who have asked similar 

Jet A, Diesel No. 1, and Diesel No. 2, are covered by different American 
Society For Testing and Materials (ASTM) specifications. The diesel fuels are 
covered by ASTM D 975, "Standard Specification for Diesel Fuel Oils". Jet A has 
the designation of ASTM D 1655, "Standard Specification for Aviation Turbine 

According to the ASTM specifications listed above, the sulfur limit for Jet 
A is a maximum of 0.3 mass %. Because of an Environmental Protection Agency 
1993 regulation, the specification for sulfur in "on road" Diesel No. 1 and 
Diesel No. 2 is a maximum of 0.05 mass % - a large difference from the Jet A 
sulfur level. 

The EPA regulation would be broken if one were to use Jet A for "on-road" 
Diesel. Jet A is also not taxed for "on-road" use, so would be illegal to 
use in "on-road" vehicles and possibly illegal in some "off-road" uses as 
well. Both the sulfur level and the tax issue need to be considered in a 
legal sense when considering the uses of these fuels.

Another difference between the fuels is the viscosity. The ASTM D 1655 
detailed viscosity requirement of Jet A is a maximum of 8 mm2/S (millimeter 
squared/Seconds - [1mm2/S = 1 Centistoke]) at -200C. The ASTM D 975 viscosity 
requirement of Diesel No. 1 is a minimum of 1.3 and a maximum of 2.4 mm2/S at 
400C and of Diesel No. 2, a minimum of 1.9 and a maximum of 4.1 mm2/S at 400C. 
It is hard to compare these, since the testing temperatures of the diesels do 
not agree with that of the Jet A. However, the viscosities at 200 Centigrade and 
in units "milliPascal/Seconds" (still another, and different unit measurement) 
for the two fuels according to a national average of four semiannual surveys 
taken from 1990-1992 are as follows:

			Jet A & Diesel No. 1		1.33
			Diesel No. 2			3.20

Jet A and Diesel No. 1 tend towards lower viscosities. Lower lubricity is 
likely as the viscosity decreases. While this may not cause catastrophic instant 
damage, it could cause long-term wear of pumps, etc.

Jet fuels have additional specifications that aren't required of diesel 
fuels. A couple examples of these are the requirement of testing for 
certain components and a volatility requirement. Some of the methods for 
testing also vary from one fuel to the other. Basically, however, we have 
pointed out the biggest differences. If you need more detailed comparisons, 
please contact the ASTM society at their headquarters at 100 Barr Harbor Drive, 
West Conshohocken, Pennsylvania 19428. They could provide you with copies of the 
specifications. Their phone number is 610-832-9500.

Once again, we stress that you should contact the equipment manufacturers 
and ask what fuels are proper for use in the engines you are curious about. 
Also, you must make certain you are not breaking any legal regulations."

So the bottom line is that although Jet-A may not cause immediate damage to 
a diesel engine and may allow the engine to run OK, its use may cause 
premature wear or fouling of the fuel system, and you may be breaking EPA 
regulations as well as not paying appropriate taxes.  Outside the US, 
differences in viscosity still mean that the use of Jet-A for Diesel No. 1 
may cause early wear of the fuel system.  Kind of like running 10 weight 
oil in a car designed for 30 weight.  So how much risk are you willing to 
take, because no engine manufacturer or fuel supplier will take part of the 

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