TM 10-3930-671-24 FUEL RECOMMENDATIONS Diesel  fuel  selection,  handling,  and  filtration  is  of  great importance.  The fuel not only supplies the energy for all the work done by the engine-it also lubricates the parts of the  fuel  injection  system  which  operate  with  very  close tolerances.      Fuel   that   contains   water,   abrasives,   or sulphur   in   excess   of   our   recommended   specifications can  cause  extensive  damage  to  the  injection  pump  and engine. DIESEL FUEL SPECIFICATIONS Continental  diesels  have  been  designed  and  developed to use ONLY No.  1-D (light fuel) and preferably No.  2D (heavy fuel)-which can be a cracked residual, a blend of preferably   a   straight-run   distillate   having   the   following characteristics:      Refer   to   Section   2   for   seasonal   fuel recommendations. (listed in order of importance) DIESEL FUEL CHARACTERISTICS EFFECT RECOMMENDE D LIMITS Cetane Number Indicative   of   Ignition   Quality,   Higher   number- better Starting and Idling. 50 desired 45 minimum Volatility: Initial Boiling Point To  prevent  premature  vaporization  during  hot weather operation. 320°F. minimum 50% recovery 90% recovery End Point Less   smoke   with   fuel   at   low   50%   and   90% Recovery   Temperatures.      Higher   end   points only partially burn, causing build up of deposits in    energy    cell    and    nozzle,    causing    pintle sticking and smoke 550°F.    Maximum 650°F.    Maximum 700°F. Maximum Distillation Recovery Lower % recovery indicates heavy  oil  fractions which cause smoke and poor combustion. 98% SU   Viscosity   100°F. (38 C) Viscosity  is  a  measure  of  flow  resistance-the low limit minimizes leakage and lubrication and the     higher     limit     insures     penetration     and atomizations. 31 - 40 seconds Water and Sediment Water   in   fuel   causes   corrosion,   rapid   pump wear and clogged fillers. .05% maximum by volume Pour Point Fuel   Oil   must   be   in   fluid   state   to   prevent clogging due to congealing wax. 10°  below  lowest anticipated operating temperature A.P.I. Gravity @ 60°F. Lower     Gravity     Fuels     contain     more     heat Units/Gal 30 minimum (A.P.I. Degrees) Total Sulphur Sulphurous acids corrode and increase engine wear. .5% maximum Corrosion  (Copper)  3 Hours @  212°F. Discoloration or pitting on polished copper strip shows same effect on engine parts. pass test Ash Amount of non-combustible material is abrasive and causes pump wear. .01% maximum by weight F-157 (F-158 blank)