TM 5-6115-593-34 NAVFAC P-8-631-34 TO-35C2-3-463-2 17-67.    A  motor  starter  will  cause  the  fuel  oil  transfer pump  to  operate  when  its  pilot  circuit  is  closed  by  the action  of  the  float  switch.    Fuel  is  then  drawn  from  the auxiliary tank via a foot valve and is pumped into the set tank.  Operation continued until the fuel level in the set tank  causes  the  float  to  rise,  opening  the  float  switch and disconnecting the fuel transfer pump motor from the power supply. 17-68.  FUEL LEVEL INDICATING SYSTEMS .    When remote     indication     of     the     quantity     of     fuel     in     an underground tank is required, a levelometer system can be  provided.    Two  types  are  available.    The  automatic type  operated  by  compressed  air  can  be  located  up  to 1000 feet (300 m) from gauged.  The manually operated type makes use of a hand pump located in the indicator case and can be located up to 150 feet (45 m) from the tank.  Dials for the levelometer gauges can be supplied calibrated  in  pounds,  gallons,  liters,  feet,  inches  or  any other unit of measurement. 17-69.  A typical levelometer system is shown in figure 17-19.    Levelometers  should  be  used  only  with  vented tanks. 17-70.  FUEL AND LUBRICANTS .  The set is capable of satisfactorily starting and operating on fuels conforming  to  VV-F-800  Grades  DF-A  and  DF-2,  MIL- F16884,   and   turbine   fuel   conforming   to   MIL-T-5624 Grade  JP-5.    All  components  of  the  engine  and  fuel system are capable of operating on Grade JP-5 turbine fuel,   except   that   rated   load   may   be   reduced   to   a maximum  of  20  percent  of  rated  kw.    When  operated continuously   on   Grade   JP-5   fuel,   the   set   meets   all requirements  except  that  the  injectors  and  fuel  pumps may  be  changed  and  timing  adjusted  from  the  diesel setting at the time of changing fuel.  The set is capable of continuous operation using lubricating oil conforming to MIL-L-9000, MIL-L-46167, and MIL-L-2104. Section VIII.  EXHAUST SYSTEM 17-71.  The engine exhaust system must dispose of the exhaust    gases    remaining    after    combustion    with    a minimum  of  back  pressure  applied  to  the  engine.    The exhaust  gas  flow  for  any  engine  will  be  approximately three  times  the  engine's  intake  and  consumption.    The adverse  effects  of  materially  exceeding  back  pressure recommendations  of  the  engine  manufacturers  loss  of power, poor fuel economy, high combustion temperatures   resulting   in   shorter   service   life,   jacket water overheating, and crankcase sludging and corrosion or bearing damage.  When the generator set is installed indoors, the exhaust system back pressure can be  kept  within  the  acceptable  limits  by  the  selection  of properly sized and installed exhaust pipe and the use of the two mufflers supplied with the set. 17-72.  When the generator set is installed indoors, it is desirable   but   not   mandatory,   to   have   the   mufflers outdoors.   This will greatly reduce the heat radiated within the building; insulating the exhaust piping with asbestos will further reduce radiated heat. 17-73.    To  ensure  an  exhaust  system  which  will  not produce   a   back   pressure   in   excess   of   the   engine manufacturer's specifications (shown in table 17-7). a.    Use an exhaust flex connector not less than 5 inch (12.7 cm) ID. b.    Use the silencers supplied with the generator set. c. Do not exceed the maximum equivalent exhaust pipe length in feet in table 17-8. 17-24