Deck Fill Protection Device
Manufactured by Marsh Marine...Tank Cleaning Professionals         “Our experience is your protection since 1966”
By Marshall Solomon M uch   of   my   business   with   Marsh   Marine   is   cleaning   diesel   fuel   and   tanks,   a   process   that   has   become   known   as fuel   polishing.      Performing   this   service   over   years   has   brought   me   into   contact   with   a   variety   of   fuel   related problems    and    the    reality    that    many    boat    owners    know    very    little    about    diesel    fuel.        There    are    many misconceptions,   false   products,   and   a   general   take-it-for-granted   attitude   about   this   precious   substance.      So   let’s pull the hatches off and really get down to understanding diesel fuel inside and out.  First some basic fuel facts: D iesel   fuel   is   a   blend   of   a   number   of   hydrocarbon   compounds   derived   from   refining   crude   oil.      Its   sister   fuels include   Kerosene   and   Number   2   Heating   Oil.     At   one   time   oil   refiners   created   diesel   fuel   from   crude   oil   through a    heating    and    condensing    process    called    fractional    distillation    which    separated    the    various    products    like kerosene,   gasoline,   naphtha,   waxes,   and   others   based   upon   their   different   boiling   points.      This   older   process produced   an   extremely   fine   product   that   was   quite   stable.      As   technology   improved   and   demand   increased, petroleum   chemists   found   they   could   boost   production   using   chemical   reactions   in   the   presence   of   various catalysts   to   break   the   complex   organic   molecules   of   crude   oil   into   simpler   molecular   compounds   (products).     These   various   methods   of   breaking   the   carbon-carbon   bonds   are   collectively   called   Cracking. Today,   cracking   is the   standard   process   of   refining   crude   oil.     As   they   say,   however,   there   is   no   free   lunch,   and   today’s   diesel   fuel   is not as stable as it once was.  Keep this important fact in mind as we move along with the discussion. D iesel   fuel   ignites   at   a   higher   temperature   than   gasoline.      That   is   to   say,   a   spark   will   not   cause   it   to   flame   like gas.      In   a   diesel   engine,   ignition   of   the   fuel   is   caused   by   the   heat   of   compression   within   the   cylinder   and   not from   a   spark   plug.      There   is   almost   twice   the   energy   stored   within   a   gallon   of   diesel   as   compared   to   a   gallon   of gasoline.      This   is   one   reason   why   diesel   engines   are   considered   more   economical   to   operate.      Gasoline   is   rated by   its   Octane   number,   like   87,   91,   or   93.      Diesel   fuel   is   rated   by   its   Cetane   number   which   is   usually   40   to   50. This   number   is   a   measure   of   the   ease   with   which   the   fuel   is   ignited   in   your   engine.      Your   engine   manufacturer determines   the   minimum   cetane   level   for   the   type   of   service   the   engine   is   intended.      Most   manufacturers recommend   diesel   fuel   with   a   cetane   number   of   at   least   40,   and   most   diesel   fuels   sold   by   reputable   dealers   meet or   exceed   this   requirement.      Diesel   fuel   with   a   cetane   of   40   to   45   is   considered   regular   while   45   to   50   is   a premium   grade.      Now,   before   you   run   out   and   buy   any   of   the   cetane   boosting   additives,   know   that   increasing   the cetane   higher   than   required   for   your   engine   does   not   materially   improve   engine   efficiency   or   operation.   Cetane level   is   seldom   a   problem.      Diesel   is   heavier   than   gasoline   but   lighter   than   water.      This   means   water,   if   present, will   be   found   beneath   the   diesel   fuel.      Marine   diesel   or   more   correctly   off   road   diesel   is   usually   red   in   color while   road   diesel   is   usually   amber   colored.      The   coloring   is   added   so   the   tax   police   can   collect   road   use   taxes which   off   road   users   don’t   pay.      I   might   add   here   that   there   is   no   certain   relationship   between   fuel   color   and   fuel quality   since   color   varies   with   crude   source,   refinery   methods,   and   dyes   used.      However,   if   the   fuel   color darkens appreciably during storage, this could indicate oxidation, contamination, or degradation.
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D I E S E L   F U E L ... Maintenance, Myths, and Truth