operation will exceed the remaining useful life of the cartridges, replace the cartridges as per paragraph 5-7. WARNING Observe     wind     direction,     make     sure compressor  air  breather  hose  is  upwind of   engine   exhaust   so   that   no   exhaust gasses are introduced into the compressor unit. e. Uncoil    and  lay  out  compressor  intake  air hose  in  the  opposite  direction  from  the  way  the  engine exhaust gasses will move, so that contaminated air is not introduced into the compressor unit. WARNING Never  attempt  to  fill  the  fuel  tank  while the  engine  is  operating  or  hot.    A  spark occurring  could  cause  an  explosion  or fire.  Do not operate the unit in a building or   an   enclosed   area   unless   exhaust gases  are  piped  outside.    Inhalation  of exhaust gases can cause serious illness or death. f. Before initially starting the diesel engine, or if  the  engine  has  been  out  of  operation  for  some  time, the hand primer (20, Figure 4-2) on the fuel supply pump should be used to pump fuel into the fuel system.  When priming, a distinct resistance to the primer pump should be felt when moving the hand primer lever up and down. Pump the hand primer five or six times. 4-34. CONNECTION BETWEEN AIR COMPRESSOR UNIT     AND     BREATHABLE     AIR     SYSTEM     TO     BE CHARGED.  A high pressure service outlet (7, Figure 4- 2)  is  provided  to  charge  scuba  service  tanks  with  up  to 3200 psi (22,048 kPa) of breathable air. 4-35. CONNECTION BETWEEN AIR COMPRESSOR UNIT AND BREATHABLE SYSTEM TO BE CHARGED. A   high   pressure   air   service   hose   should   be   used   to charge  breathable  air  systems.    The  air  service  hose  is equipped  with  a  high  pressure  air  chuck.    The  chuck should be connected to the valve fitting of the item to be charged.  To charge a system, proceed as follows: WARNING Never connect  the  air  service  hose  to  a pneumatic  system   without   first   making certain that HIGH PRESSURE SERVICE valve is closed and the HIGH PRESSURE  SERVICE  gauge  indicates zero psi.  Never disconnect the air service   hose   after   charging   a   system without  making  certain  that  the  service valve    is    closed,    and    the    SERVICE HOSE BLEED valve is open to relieve all air pressure in the air service hose. CAUTION The   stems   and   seats   of   the   control panel    valves    may    be    damaged    by overtightening.      All   valves   should   be tightened only enough to prevent leakage. a. Close    all    control    valves    on    the    control panel. b. Connect    service    hose    to    breathable    air service connector as required. CAUTION When  ambient  air  temperature  is  32°F (0°C)  or  above  keep  air  cooler  doors open during air compressor unit operation.    Below  32°F  (0°C)  ambient, keep  air  cooler  doors  closed  during  air compressor unit operation. 4-36. STARTING   UNDER   NORMAL   CONDITIONS, ABOVE  32°F  (0°C).    Perform  the  Prior  To  Operation Procedures     (Section     IV).          Make     the     necessary connections described in CONNECTION BETWEEN AIR COMPRESSOR  UNIT  (Section  IV)  and  BREATHABLE AIR SYSTEM TO BE CHARGED.  Proceed as follows: a. Make  certain  CLUTCH  handle  (11,  Figure 4-3) is in disengaged position, away from control panel. b. Make certain  COMPRESSOR  UNLOADER switch  (16,  Figure  4-3)  is  in  the  UNLOAD  position  and close all control panel valves. c. Make certain ENGINE THROTTLE CONTROL  (10),  is  positioned  half  way  in  (idle  position 1,100 ± 100 rpm [1,100 ± 100 r/min]). d. Turn   MASTER   SWITCH   (9)   to   45°   cw position. CAUTION If  engine  oil  pressure  does  not  register on gauge within five seconds, shut down engine  and  determine  cause.    Refer  to Troubleshooting (Section V). e. Push   engine   START   switch   (8).      When engine   starts   continue   to   hold   START   switch   until ENGINE OIL PRESSURE gauge (6) registers pressure; then, release START switch. 4-7