TM   5-4930-227-14 2-13.   Operation   in   Extreme   Heat a.  General.  Accumulated  dirt  on  engine  re- duces radiation of heat. Keep the unit clean to avoid  overheating. b.  Cooling  System. (1)  Keep  the  engine  cooling  fins  clean. (2) Keep all exposed surfaces of the engine clean. (3)  Remove  all  obstructions  to  the  flow  of air across the engine. c. Lubrication. Refer to lubrication order, LO 5-4930-227-12. d. Pumping Unit.  Where  possible,  operate  the pumping unit in the shade to avoid overheating and  do  not  run  the  engine  too  hard.  If  the engine overheats, remove the load and idle the engine  at  1,000  rpm  for  five  minutes.  If  fuel vapor lock occurs, wait until the engine cools off. e. Tanks and Hoses.  Locate the tanks in the shade,  where  possible,  and  wet  down  with  water to  reduce  heat. 2-14.  Operation  in  Dusty  or  Sandy  Areas a.  Protection.  Take advantage of natural barri- ers to blowing sand and dust; or, if necessary, erect  artificial  barriers. b.  Air  Cleaner.  Service  the  air  cleaner  fre- quently (para 3–27). c. Filter/Separator Element. Service   the filter/separator frequently (para 3-11). d.  Cleaning.  Clean  the  tank  and  pump  unit with an approved cleaning solvent, giving special attention to cavities, corners, and partially ex- posed  interior  spaces.  Dry  thoroughly.  Keep  the tank and areas around the discharge valve and controls free from sand  and dust. 2-15.   Operation   Under   Rainy   or   Humid Conditions When the unit is outside and not operating, pro- tect it with a canvas or other waterproof cover. Remove the cover during dry periods to allow the unit to dry out. Keep the fuel tank full to pre- vent the forming of condensate. Give special care to keeping all components free from moisture. Clean and paint all surfaces not otherwise pro- tected. 2-16.  Operation  in  Salt  Water  Areas Salt water corrodes metal. If unpainted equip- ment parts are exposed to salt water, clean them off immediately with an approved cleaning sol- vent,  and  dry  thoroughly.  All  surfaces  should be  cleaned  daily. 2-17.   Operation   at   High   Altitudes The  unit  is  designed  to  operate  at  8,000  feet above  sea  level  without  special  adjustments. However, at higher altitudes, the carburetor may require adjustment (para 3-28). Section  V.  OPERATION  OF  AUXILIARY  MATERIEL  USED  IN CONJUNCTION  WITH  THE  TANK  AND  PUMP  UNIT 2-18.   General This  section  contains  information  on  the  fire  ex- tinguishers  and  the  fueling  meter.  The  dry-chemi- cal type fire extinguisher (para 2-19 ) is a non- shatterable,  hand-type  extinguisher.  The  fueling meter   is   a   volumetric, positive-displacement, liquid-measuring  device,  used  when  refueling aircraft or any vehicle which requires a specific measurement  of  the  product.  It  is  equipped  with a  five-figure  reset  counter  and  a  nonsetback totalizer that registers to 9,999,999 gallons. 2-19.   Fire   Extinguisher   (Dry-Chemical   Type) a. Description. The dry-chemical type fire ex- tinguisher is suitable for electrical and flammable liquid  fires. 2-14 b. Operation.  Remove  fire  extinguisher  from mounting bracket. Release nozzle from holster. Pull pin. Press lever all the way down to pressur- ive   extinguisher.   Hold   extinguisher   upright, squeeze  nozzle  lever  to  fully  open  and  direct discharge at base of flame, using rapid side-to- side sweeping motion. Always keep flames ahead of  dry  chemical  charge. 2-20.   Metering   Kit A  metering  kit,  FSN  4930-088-7665,  is  available for  pumping  assemblies  on  an  as  required  basis. 2-21.   Meter   Register   Operation To reset indicating wheels to zero, push in and turn reset knob on right side of register.