The fuel normally used in diesel engines is naval distillate (NATO symbol F-76), but other fuels such as JP-5 (NATO symbol F-44) and naval distillate lower pour point (NATO symbol F-75) are also used. Code F-76 and F-75 fuels are compatible and can be mixed in all proportions. Code F-44 and F-75 fuels are authorized for use in diesel engines where there is a logistic advantage for use. At present, most ships carry naval distillate fuel (F-76) for boilers and for diesel engines.

SHIPBOARD FUEL TESTING

Normally, fuel is procured through the military supply system. It is reasonable to assume that fuel received from the military supply system will meet the requirements of the applicable military fuel specification because of the extensive quality surveillance procedures used by this system. However, when delivered to ships by fleet oilers, fuel can be contaminated by solids and water. Solids and water must be removed by the receiving ship through settling and stripping or by use of purification equipment.

The fuel testing equipment items described in this section will help you identify the solids and water that must be removed by stripping and determine whether the purification equipment is functioning adequately to remove the solids and the water.

Required shipboard fuel testing equipment items for all ships are as follows:

In addition to these four tests, if you are an Engineman assigned to a ship with gas turbine propulsion plants or helicopter in-flight refueling (HIFR) capability, you will be required to have the following additional testing equipment:

1. A.E.L. free water detector Mk II

2. A.E.L. contaminated fuel detector Mk III

For detailed information on shipboard testing, consult the Naval Ships Technical Manual, chapters 541 and 542.