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precautionary measure to guard against the recurrence of underground losses. The method hereinafter prescribed for making a water-waste survey is applicable to usual navy yard conditions, but variations may be made if necessary, provided the accuracy of the survey is not affected thereby.

20-72. Source of losses. Underground losses may occur through gradual deterioration of the system, breaks, pulled joints, stuffingbox leakage at valves, or imperfectly closed hydrants. The detection of such losses at a navy yard is especially difficult owing to the small exposure of natural soil, the proximity of the water front, and the extended system of underground drains; systematic investigation under such circumstances is therefore required. In addition to the losses mentioned, further wastage may occur through leaky faucets and other fixtures, or by the unnecessary use of automatic flushing equipment.

20-73. Method of making water-waste survey. In preparation for a general water-waste survey, the accuracy of all meters on supply mains must be determined beyond question; they should be carefully tested by comparison with a calibrated meter, by pitometer measurements, or by any other convenient and reliable method; care should be taken to run tests at various rates of flow, so that the entire range of possible demand shall be covered.

20-74. Installing meters on all services. The next step is to make a careful inspection to locate any unauthorized or unmetered connections to the mains, by-passes around meters, and any broken or defective meters; all buildings, ships, or other activities where unmetered connections are discovered should be equipped with suitable meters. All services and outlets within the station should be metered, if it is in any way practicable to do so. During the period of the survey it is desirable that arrangements be made to meter the consumption of such movable consumers as locomotives, cranes, and concrete mixers, and these arrangements should be continued where practicable.

20-75. Eliminating surface leaks and unnecessary uses. A thorough inspection should next be made of piping and fixtures in all structures where fresh water is used; leaks, drips, and unnecessary automatic or continuous flushing should be eliminated. These inspections should preferably be made at night, and should be

supplemented by meter readings and listening devices, such as the "aquaphone." Wasteful practices in the use of water for latrines, toilets, washhouses, laundries, restaurants, lawn sprinkling, and other purposes should be given special attention and corrected.

20-76. Determination of daily consumption and minimum night rate. Having completed the inspection of all visible lines and outlets, eliminated all unnecessary uses of water, and metered all connections in so far as practicable, the next step is to determine the daily consumption of water and the minimum night rate. This should be done by making a 24-hour test, during which time the main meters are read hourly, or, if feasible, at shorter intervals, say 15 minutes, during the hours of anticipated low consumption. With few exceptions, such as the central power plant, latrines, and barracks, there is no consumption during certain night hours; consequently readings of meters on such services should be made concurrently with the main meters, or as nearly so as practicable, during the night hours when consumption is lowest. If practicable, the night test should be made with only one main meter in operation, other meters being temporarily cut out. The daily consumption of all activities which consume no water at night can be determined by two readings of each meter, one at the beginning and one at the end of the 24-hour test period. A comparison of the summation of the main meter readings with those of all the yard meters gives the leakage in mains, valves, and hydrants, and also losses through unmetered connections. A comparison of the minimum night rate indicated by the main meters with corresponding readings of nightconsumer meters shows the losses due to leakage alone.

20-77. The location and elimination of underground leaks in all mains and branches is the final step in the survey. To accomplish this it is necessary to investigate the entire system between the main meters and building meters in the following manner:

(a) Divide the yard into a convenient number of sections so chosen as to permit closing off any section by valves without affecting the remainder of the system.

(b) Install a metered by-pass around each valve selected to "feed" a given section. This can be conveniently done by inserting three-fourths-inch corporation cocks on either side of the valve and connecting a three-fourths-inch disk meter with heavy rubber steam hose having pipe union ends. A sufficient length of hose should be

used to permit the meter being set on the ground when the valve is in a manhole.

(c) Isolate the section and test all control valves for tightness.

(d) Feed the section through the metered by-pass, reading the meter at the end of each minute. Successively close the valves on all branch lines in the section, noting in each case the time of closing. Allow several minutes between successive closings so that the effect of each will be independently shown by the meter readings. If, after closing all secondary valves, a flow through the metered by-pass is still noted, reduce the size of the section step by step, by closing valves in order, beginning with the farthest from the meter. These observations can best be made during the night hours, say from 11 p.m. to 7 a. m., or other suitable night hours, because interference with the water supply to buildings, ships, and quarters will thus be avoided, and also because during most of this period the system will be comparatively free from fluctuating drafts of water.

(e) Locate leaks and make repairs. By using time and rate of flow as coordinates, a curve can be plotted showing the variations in flow throughout the test of any section. By noting the time of closing each valve on the curve it can be readily seen which valves have affected the rate of flow and leaks can then be definitely identified with particular sections of pipe. When a leak is to be located in a long section of water main, the use of the "aquaphone" in test pits frequently gives good results without excessive excavation. Other methods failing, such leaks may be located with reasonable accuracy by installing test cocks at suitable points and then introducing into the main a quantity of harmless colored liquid having a density different from that of water. The rate of leakage being known in advance, the time required for the solution to reach certain points in a tight section of pipe of the size in question can be easily computed. The position of a leak will be indicated by a comparison of the actual with the theoretical time required for the colored liquid successively to reach the selected outlets or test cocks along the line.

20-78. Survey arrangements to be made permanent. The arrangements for making water-waste surveys should be made permanent, so that surveys may be repeated with slight cost. It is also very necessary to instruct the testing crew thoroughly as to the various steps and the reasons therefor, so that in succeeding surveys the same procedure may be followed without special study and instruction.

20-79. The quarterly night test, mentioned in par. 20-71, is simply the comparison of main meter readings with those of the night consumers from midnight to 8 a. m., or other appropriate night hours, in order to determine the losses due to leakage.

20-80. Constant vigilance required to prevent wastage. Even after a successful survey, wastage can not be prevented except through constant vigilance in controlling issues to ships and other consumers not permanently metered, and in keeping the number of unmetered connections to the absolute minimun.

BUILDINGS, CHIMNEYS, WALLS, AND FENCES.

20-81. Maintenance work consists of the execution of any measures necessary to insure continued stability of the structure in whole or in part, such measures to include the prevention of overloading or otherwise hazarding the structure or any of its parts; the prevention of avoidable deterioration through the prompt detection and repair of defects and damages; the reduction of deterioration from the elements by such preservative measures as may be practicable; and decorative treatment to secure appearance appropriate to the intended purpose of the structure.

20-82. Scope of instructions. Since types of structures, in the case of buildings, vary from single-story wooden structures to multistoried structures of steel and masonry, with wide variation also obtaining in types of chimneys, walls, and fences, it is impracticable to prescribe maintenance rules in complete detail. The succeeding instructions in this section will therefore be limited to those considerations common to all such structures, and furthermore without regard to particular climatic conditions.

20-83. Foundations. Any material or general settlement of footings must be promptly and thoroughly investigated, and necessary corrective measures adopted. If the structure is of any considerable value or importance, full report shall be made to the bureau. Temporary foundations should be given such attention as the importance of the structure justifies.

20-84. Roofs should be so maintained that the necessity for their complete renewal may be postponed as long as economically practicable. Roofs should be renewed when the annual maintenance cost exceeds the interest on the capital investment required for renewal; shortage of funds under the appropriation applicable, may, however,

often delay such work beyond the point of justifiable renewal. The system of routine inspections should be such as to disclose leaks and other defects, particularly during rainy weather, without relying upon the occupant to report them. Buildings with skylights require extra attention on account of the inherent likelihood of leaks developing in this type of construction. Gutters and leaders should habitually be kept tight and free from obstruction.

20-85. Painting of exposed masonry forbidden. The painting of exposed exterior brick, stone, or concrete in building walls, boundary walls, or retaining walls is forbidden, the practice being not only wasteful but useless. In the case of masonry structures already painted, the bureau's advice as to proper future treatment should be obtained before repainting such structures.

20-86. Painting for decorative purposes only shall not be performed except in buildings or parts thereof used for administrative or living purposes. Instructions as to the bureau's standards and practice regarding the use of paints have been placed under a separate heading in this chapter.

20-87. Linoleum not to be shellacked. Linoleum is frequently used for covering floor areas used for offices and hallways. Subject to certain limitations, the bureau approves such practice. Linoleum purchased under standard Navy specifications is usually carried in store by the supply officer, and is entirely suitable for offices and hallways, although the medium three-sixteenths-inch weight is preferable. New linoleum shall not be covered with shellac, because it induces rot, and when once applied prevents any treatment other than repeated applications of more shellac. Immediately after laying, linoleum should be well rubbed with linseed oil and allowed to dry. At necessary and convenient intervals and after cleaning with water, the application of linseed oil with a small quantity of Japan drier can be repeated to renew the life of the linoleum. When badly discolored, linoleum may be treated with a stain containing the following ingredients per gallon:

Venetian red in oil, 2 pounds.
Raw linseed oil, gallon.

Turpentine, 2 pints.
Japan drier, pint.

This stain should be well rubbed in and allowed to stand 24 hours before traffic is permitted. Another approved treatment for linoleum is the following: Dissolve any satisfactory brand of commercial

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