stacks,  to  determine  the  true  state  of  combustion efficiency. NOTE: In boilers using distillate fuel, excess air can   cause   abnormally   high   superheater   outlet temperatures, especially on “D” type boilers. Be very careful to prevent leakage of air into a boiler. Air that enters a boiler at any place other than through a burner register does not contribute to furnace combusiton and may  reduce  combustion  efficiency. . Watch carefully for chloride contamination of the water in the boiler feed and condensate systems; it threatens   the   material   integrity   and   operational readiness of  the plant. Keep in good working order those means used to determine the chloride content of boiler water.  Drill  operating  personnel  frequently  on  the danger of, and the methods used to prevent, chloride contamination.  Be  sure  the  DFT  is  functioning  properly to remove dissolved gases from the boiler feedwater. l Conduct daily dissolved oxygen tests on water to steaming boilers and on the discharge side DFT if  your ship has them. You don’t want dissolved oxygen in any boiler, but it is particularly corrosive in boilers that operate at high pressures and high temperatures. The modern  pressure-closed  feed  system  is  designed  to  keep the condensate and feedwater from being exposed to air, and  the  DFT  is  designed  to  remove  a  great  deal  of oxygen that becomes dissolved or entrained in the water. However, there are still many ways  in which oxygen can get into the system and become dissolved in the water. For example, a defective DFT may allow the water to pass   through   without   being   deaerated.   Incorrect operation of a DFT can have the same effect. Air can leak into the condensate and feed systems at various points and its oxygen can dissolve in the water. Failure to lay up idle boilers according to prescribed procedures is still another cause of dissolved oxygen. You can find more  information  on  dissolved  oxygen  tests  in  NSTM, chapter 220. .  The  Oil  King  and  the  engineering  watch supervisors in the fireroom should be graduates of the Boiler Feedwater Test and Treatment Course. They should  be  certified  to  perform  the  feedwater  tests  and treatments  that  are  prescribed  by  Naval  Sea  Systems Command  (NAVSEASYSCOM)  and  the  manufacturer of the boilers. Never assume that personnel who conduct these  tests  are  competent,  observe  them  personally  and be sure. . Always preheat the lubricating oil system before starting the engines. During operating periods, keep the oil from the oil cooler between 120 and 130 degrees to minimize  bearing  wear.  Watch  for  overheated  bearings, foaming or emulsified oil, the presence of bearing metal and other foreign particles in lubricating oil sumps, and the presence of rust on journals and gearing. .   When   condensers   and   their   auxiliary components are operated improperly, they can cause extensive loss of efficiency.  Here are several examples. — — l When you use more than the required amount of cooling water, the condensate system pumps a large amount of heat overboard, and the boilers will have to replenish that lost heat. You’ll get the same  effect  from  recirculation  of  the  condensate. Air leaks in the condenser or its components may overload the air ejectors and lower the vacuum. Steam is wasted by fluctuating, or excess, steam pressure to the air ejectors and by steam-driven auxiliary  pumps  operated  at  higher-than- necessary  speeds. When  the  weather  is  cold  enough  to  require steam heat, try to operate ventilation motors in fresh air supply systems at slow speeds. If you must operate them at higher speeds, first secure the steam to preheater and reheaters, but never operate supply blower motors faster than necessary for comfort. It is usually more efficient to circulate fresh air in a compartment by operating the exhaust blower at a faster speed. .  Keep  engineering  spaces,  equipment,  and machinery clean–it is one of the most important sound engineering practices. Clean up trash and spilled oil to prevent  accidents  and  fire.  Keep  machinery  free  of  oil and dirt so oil and fuel leaks are easily visible. Repair all leaks promptly. NEVER hose down spaces above the level of the bilge deck plates–you may get water in electrical assemblies. Clean spaces, equipment, and machinery show pride in your work and your ship. You can find information on performance data and operating limits of the plant’s equipment and machinery in the NSTM, manufacturers’ technical manuals, and the Ship Information Book (SIB). For older ships, look in the General  Information  Book,   the Piping   System Instruction Book, the Record of Electrical Installations, the  Electrically   Operated   Auxiliaries   With Performance  Data,    and  General   Description   of Electronics  System  Installation. 4-3