7.35 a. m. start the condenser and auxiliaries; and at approximately 7.45 a. m. place alternator upon the line. If the furnace and dry docks are not to be operated that day, the 1,000-kw. turbo alternator will be taken off the line and shut down. The 3,200-kw. machine will operate at approximately load until 5 p. m. At 4.30 p. m. the 1,000-kw. alternator should be started, the machine warmed up, condenser and auxiliaries started at 4.50 p. m., and unit placed on the line at 5 p. m. The 3,200-kw. machine should then be shut down, the 1,000-kw. turbo alternator carrying the night load. When the electric furnace is to be operated during the day, the power plant engineer should be notified. In this case the 1,000-kw. turbo alternator would be operated in parallel with the 3,200-kw. machine until 12 m., when it would be shut down for one hour. If Dry Dock No. 1 is to be pumped, the watch on duty at 8 a. m. will warm up an additional 3,200-kw. turbo alternator and start the second exciter. The condenser and auxiliaries should be started at 8.35 a. m., and the machine placed on the line at approximately 8.45 a. m. The 1,000-kw. and two 3,200-kw. turbo alternators would operate at approximately 94 per cent load, leaving a margin of about 400 kw. to take care of peaks. At 12 m. the 1,000-kw. machine would be shut down for inspection. If Dry Dock No. 2 is to be pumped in the afternoon, the 1,000-kw. turbo alternator need not be operated, as the two 3,200-kw. machines would have ample capacity to carry the load. The circulating pumps serving the condenser should be started and stopped at the same time anxiliaries serving turbines are shut down or started, keeping only sufficient circulating pump capacity in service to maintain a temperature of water leaving the condensers at approximately 15° F. less that of the condensate temperature. In preparing operating schedules weight must be given to the amount of steam required to warm up the various units when shifting, the desideratum being lowest over-all consumption of steam.

21-44. Operating schedule conditions based on compressed air load curve. Plate No. 21-2 shows a typical load curve for plant with an installed capacity of one 3,000-c.f.m. and one 5,000-c.f.m. reciprocating air compressor, and also one 5,000-c.f.m. mixed-pressure turbo compressor. If the power plant operating force has not been notified to prepare for the maximum load, the watch on duty at 7 a. m. will warm up the 3,000-c.f.m. compressor, starting its condenser and auxiliaries at 7.20 and bringing the machine up to speed at 7.30 a. m. The turbo compressor should then be warmed

up and placed in service by 8.15 a. m., using the exhaust steam from the 3,000-c.f.m. compressor in the mixed-pressure turbine. At 12 m. the turbo compressor may be shut down during the lunch hour. Turbo compressors should be again started before the end of the lunch period and operated until 4.45 p. m. They should then be shut down and at 5 p. m. the reciprocating air compressor should likewise be shut down. If the maximum load is expected of the plant, the watch on duty at 7 a. m. should warm up the 5,000-c.f.m. reciprocating compressor and bring it up to speed by 7.30 a. m.; then warm up and start the turbo compressor, utilizing exhaust from the reciprocating machine, and place the turbo compressor in service about 8.15 a. m. Shut turbo compressor down at 4.30 p. m. and reciprocating compressor at 5 p. m., regulating the circulating pumps to maintain circulating water leaving condensers at approximately 15° F. less than the condensate temperature.

21-45. Typical boiler loads. The curves and table, Plate No. 21-3, show a typical schedule of boiler operation for an assumed power plant, together with certain relations which should exist between the load on a water-tube boiler with underfeed stoker and the efficiency, pounds of coal consumed per horsepower per hour, draft, wind-box pressure, volume of air, and temperature of exit gases.

21-46. Preparation of boiler operating schedules. The power plant engineer should construct curves similar to those of Plate No. 21-3 for the boilers in his plant, and should determine from these the most economical load to be carried on various combinations of boilers. A feature which should be given especial attention in determining the maximum continuous rating at which a boiler should be operated, is the rate of depreciation of the fire-brick lining when carrying loads considerably above rating for protracted periods.

21-47. Schedules for inspection and maintenance of equipment. Experience has shown that apparatus can not be maintained in condition to render satisfactory and economical service unless a definite schedule of inspection is established and carried out intelligently and systematically for each piece of equipment in the power plant. These schedules are intended to give detailed instructions for the inspection of all parts of apparatus which are subject to wear, deterioration, and adjustment, and they also state the frequency of such inspections. The bureau desires that such schedules be fol

lowed out in detail, so far as can be accomplished with the force available. The power-plant engineer should assign definite sections of the schedule to such of his assistants as are properly qualified to perform this work, and should hold them responsible for carrying out the instructions contained therein and for reporting to him at once, in writing, any conditions found which require adjustment, repair, or replacement of parts to insure the best and most economical operation.

21-48. Typical inspection and maintenance schedules for boilers, generating units, and air compressors are reproduced on succeeding pages. When an inspection has been completed on a particular item a horizontal line should be drawn across the space opposite the item and in the time column showing the frequency of inspection; date of inspection may also be entered. The schedules shown will form a basis for preparation of a complete schedule for all apparatus. The schedules outline a system of maintenance and inspection covering, in the main, such details of station equipment as may reasonably be expected to require thorough overhaul at intervals not more frequent than weekly. Aside from these, however, there are certain parts of the apparatus which for reliability and economy of operation must receive inspection daily, and other parts requiring almost constant attention. The complete listing of duties of this kind is impracticable.

21-49. Purpose of the schedules. The instructions as to schedules are by no means intended to give relief from any previously assigned duties or responsibilities. The real purpose to be served by the schedule is that, through systematic inspection and overhaul of every detail of the apparatus according to plans carefully laid out, not merely may serious breakdown be avoided, but that the station may be maintained at the highest efficiency at every point and so maintained at a minimum of cost.

THE BOILER ROOM.

21-50. Fireroom operation. Operation of the boiler plant is very important, and it is essential to its economic operation that the boiler-room crew be kept fully informed as to the condition of load and as to any anticipated changes either of load or of equipment operated. It shall be the duty of the watch engineer to keep the boiler room so informed. Further, the fireman in charge must at all times give close attention to the loading of his boilers to see that

the number of boilers in service is held at that which will most efficiently carry the load. (Refer to schedule for boiler operation.) He must make frequent visits to the boiler room and at such times always observe the condition of the fires and examine the records of the various recording gauges in the fireroom (steam-pressure gauge, flow meters, feed-water thermometers, and CO, recorders), with a view to determining conditions of operation since the previous round, making such corrections as may be necessary. He must further be present whenever a boiler is blown down, and must see that all banking, cutting in, and cutting out of boilers is done without unnecessary waste of fuel and in accordance with instructions prescribed. Except as required in emergency, any boiler which it is desired to cut out for overhaul, repair, or cleaning must be cut out at a time when the load on the plant falls sufficiently to permit of sparing the services of that boiler. Correspondingly, boilers which it is desired to cut in must, except in cases of emergency, be fired up during the night and cut in as they are required in the morning.

21-51. Flue gas content. Bolier-room operatives must at all times give especial attention to the per cent CO, as indicated by the gauges in the fireroom, and should use every effort to maintain this as nearly at 14 per cent as possible. The cause of any fluctuations from this point must be investigated at once and remedied as promptly as possible, either by a more careful stoking (see instructions on operation of stokers in another part of this chapter), or by an adjustment of the dampers on the individual boilers.

21-52. Damper position. The movement of the damper position indicator, except as affected by a sudden marked fluctuation in load, affords a most reliable and sensitive guide to the condition of fires. With boilers operated in accordance with schedule prescribed, there is a correct range for damper position. This range must be determined by the engineer in charge, and instructions shall be issued to the firemen that movement of the position indicator beyond the range established indicates improper condition of the fires, which must be ascertained and remedied at once.

21-53. Fireroom cleaning. The operatives employed for coal. and ash handling are to be responsible for the general cleanliness of boiler room, boiler tops and settings, and economizer tops and settings. The work in connection with coal and ash handling should be completed at as early an hour as possible in order to allow time

for other duties. Whenever practicable, coal bunkers should be filled first each day, after which ashes should be removed and other duties in connection with coal and ash handling plant maintenance performed.

21-54. Ash removal. Where ash hoppers are not provided it should be the duty of the firemen to draw the ashes from the ash pits as soon as dumped, to prevent reduction of draft and warping of grate bars. During evening and night watches the refuse ashes. should be handled entirely by the firemen on watch.

21-55. Cleaning of boilers. All boilers must be shut down for external cleaning and inspection of furnace and grates after not more than 720 hours of steaming as a maximum, exclusive of time fires are banked, and at this time must receive thorough cleaning of fire side of tubes, etc.; removal of soot from combustion chamber; cleaning out and repair of furnace and grate; repair of setting and baffles; examination and overhaul of blow-off valves, as required; and overhaul of water columns. Under the personal supervision of the engineer in charge, observation shall be made to determine the rate of deposit of scale. As the result of these observations a schedule shall be prepared to govern the frequency of internal cleaning. Such cleaning should be done only at such intervals as will insure efficient operation. Ordinarily the cleaning will be required more frequently for the lower rows of tubes than for the remainder of the boiler. The character and extent of the scale formation must be under constant observation in order that the schedule may be modified to meet the changing requirements due to variation in the quality of the feed water. The periodical internal cleaning must be thorough and complete in every particular.

21-56. All boilers out of service for internal cleaning should receive thorough internal and external cleaning and careful examination for deterioration; overhaul of stop valves, feed valves, blow-off valves, and of safety valves; adjustment of steam gauge and inspection of safety fusible plugs, if provided; and, upon returning to service, adjustment of safety valve. Whenever a boiler or any other piece of important apparatus is taken out of service for any cause, the effort should be made to complete promptly any work which may be required upon it.

21-57. All boilers shall be inspected quarterly, and reports submitted on Y&D form 91 to the Chief of the Bureau of Yards and