ENGINEMAN  1  &  C and dirt when new gears or bearings are wearing in or after they have been opened for inspection. Lint or dirt, if left in the system, may clog the oil spray nozzles. The spray nozzle passages must be open at all times. Spray nozzles should not be altered  without  proper  authorization. Although the lubricating oil strainers perform satisfactorily  under  normal  operating  conditions, they cannot trap particles of metal and dirt which are fine enough to pass through the mesh. These fine particles can become embedded in the bear- ing metal and cause wear on the bearings and journals.  These  fine  abrasive  particles  passing through the gear teeth act like a lapping com- pound and remove metal from the teeth. EFFECTS  OF  WATER  AND  ACID  IN OIL.—Water in the oil is extremely harmful. Even small amounts soon cause pitting and corrosion of the teeth. Acid can cause even more serious problems. The oil must be tested frequently for water, and periodic tests should be made for acid content.  Immediate  corrective  measures  must  be taken when saltwater is found in the reduction gear lubricating oil system. Occasionally gross contamination of the oil by saltwater occurs when a cooler leaks or when leaks develop in a sump. The immediate location and sealing of the leak is not enough. Additional steps  must  be  taken  to  remove  the  contaminated oil  from  all  steel  parts.  Several  instances  are known   when,   because   such   treatment   was postponed—sometimes  for  a  week  or  less—gears, journals, and couplings became so badly corroded and pitted that it was necessary to remove the gears  and  recondition  the  teeth  and  journals. Saltwater contamination of the lubricating oil may also cause bearing burnout. Water, in small amounts, is always present within the lubrication system as a result of con- densation.  Air  which  enters  the  units  contains moisture.  This  moisture  condenses  into  water when it strikes a cooler surface and subsequently mixes with the oil. The water displaces the oil from the metal surfaces and causes rusting. Water mixed with oil also reduces the lubricating value of the oil itself. When the main engines are secured, the oil should  be  circulated  until  the  temperature  of  the oil and that of the reduction gear casing approxi- mate  the  engineroom  temperature.  While  the  oil is being circulated, the cooler should be operated and  the  gear  should  be  jacked  continuously.  The purifier should also be operated to renovate the oil while the oil is being circulated and after the oil circulation is stopped until water is no longer discharged  from  the  purifier.  This  procedure eliminates condensation from the interior of the main reduction gear casing and reduces rusting in the upper gear case and gears. Generally,  lubricating  oil  will  be  maintained in good condition if proper use is made of the purifier   and   settling   tanks.   However,   if   the purifier does not operate satisfactorily and does not have the correct water seal, it will not separate the water from the oil. You can check for the presence of water by taking small samples of oil in  bottles,  and  allowing  the  samples  to  settle. These samples should be taken from a low point in the lube oil system. Samples of lubricating oil should be tested at every opportunity for acid, water, and sediment content  at  a  naval  shipyard  (or  other  similar activity). With continuous use, lube oil increases in acidity, and free fatty acids form a mineral soap which reacts with the oil to form an emulsion. As the oil emulsifies, it loses its lubricating quality. Once the oil has emulsified, the removal of water and other impurities becomes increasingly dif- ficult. When the formation of a proper oil film is rendered impossible, the oil must be renovated. Sometimes, when a ship from the reserve fleet is placed back in commission, the rust preventive compound is not removed completely. The residue of  this  compound  may  cause  serious  emulsifica- tion  of  the  lubricating  oil.  Operating  with emulsified oil may result in damage to the bear- ings or the reduction gears. Since it is extremely difficult  aboard  ship  to  destroy  emulsions  by heating, settling, and centrifuging, you must make sure  that  emulsions  do  not  occur.  At  the  first indication of an emulsion, the plant should be stopped and the oil renovated. MAINTAINING   FOR   PROPER   OIL LEVEL.—It is of extreme importance that the quantity of oil in the sump be maintained within the prescribed maximum and minimum levels. Too much oil as well as too little oil in the sump can lead to trouble. If the oil level is above the 4-2