Part 24

The important feature in the design of such tanks is to see that they are properly braced with hoops, and it is usual to specify that no hoop shall be subjected to a unit stress of more than 12,000 pounds for iron and 16,000 pounds for steel. These hoops are made from ¾-inch to 1-inch round iron, not less than the former, and the required strength is obtained by spacing them closer together at the bottom and farther apart toward the top. They are held together with adjustable clamps, as indicated in Fig. 33, and by the use of such clamps they may be readily tightened. The bottom hoops of the tank are subjected to great stress, and it is good practice for these hoops to bear against a flat iron hoop, as indicated in Fig. 34. By this construction much greater bearing is provided on the wood, and the round iron is prevented from cutting into the staves of the tank. In some instances flat iron hoops are used altogether, but it is considered better to use round iron hoops, from the fact that they are not likely to corrode through as rapidly as the thin flat iron.

=69. Proportioning the Hoops.=—The principal element of engineering entering into the design of large wooden water tanks consists in the proportioning of the hoops, and Table II will be found convenient in determining the hoops required for any size of tank.

=70.= In order to determine the number of hoops of a certain size required for any span of 12 inches at a point any distance from the water-line, the following formula may be used:

5.16 _d H_ _N_ = ----------, _S_

in which _N_ = number of hoops required in 1 foot of height of tank; _d_ = diameter of tank, in inches; _H_ = height of water-line from center of space under consideration, in feet; _S_ = actual safe strength, in pounds, of hoops assumed to be used.

This last value may be found from Table II.

TABLE II

SAFE STRENGTH OF ROUND TANK HOOPS =========+=========+============= Diameter | Steel | Wrought Iron Inch | Pounds | Pounds ---------+---------+------------- ⅝ | 3,232 | 2,424 ¾ | 4,832 | 3,624 ⅞ | 6,720 | 5,040 1 | 8,800 | 6,600 =========+=========+=============

=71.= To illustrate the foregoing, assume that it is desired to find what will be the spacing of ⅞-inch steel hoops at the bottom of a tank 12 feet in diameter, in which the water-line is 16 feet from the middle of the section under consideration. Applying the formula in Art. =70=, using in conjunction therewith Table II, it is found that

5.16 × 144 × 16 _N_ = --------------- = 1.77. 6,720

This result, 1.77, is the number of hoops required in 12 inches of height from the bottom of the tank, and would indicate that the hoops should be spaced about 7 inches from center to center, for 12 inches divided by 1.77 gives approximately 7 inches, the pitch of the hoops. This process should be repeated for different points throughout the height of the tank, and from the results the tank may be designed.

=72.= In the installation of sprinkler tanks, it must be observed that they are placed some distance above the highest point of the top floor, the distance usually required by the Underwriters being 20 feet, if it is possible of attainment. The tank should always be roofed, have a ladder from the roof of the building to its top, and a steam pipe inside to prevent the water from freezing in winter. This pipe is furnished with a check-valve to prevent the water in the tank from siphoning.

EXAMPLE FOR PRACTICE What should be the spacing of the ¾-inch round wrought-iron hoops on a tank 10 feet in diameter and 12 feet high at a distance of 6 feet from the water-line? Ans. 12 in.

=73. Automatic Sprinkler System.=—The sprinkler system as now installed for protection against fire in the interior of a building consists essentially of piping connected to a gravity tank and extending over the entire ceiling by means of mains and branches. There is located on the ends of the branches automatic valves or stops, which are collapsed or opened by the melting of a fuse or solder at a temperature more than is likely to exist in the room at any time and still below that which would be created by an incipient fire.

=74.= The underlying principles of automatic sprinkler systems as stated by the Underwriters are as follows:

1. Buildings must be open in construction, free from concealed spaces, or places where water thrown from sprinklers cannot penetrate.

2. Sprinklers to be so located that their distribution will cover all parts of the premises.

3. Sprinkler piping to be of sufficient capacity and to have water under pressure in same at all times, except in case of a system where freezing is likely to occur, where an air lock is used.

4. An automatic supply of water of sufficient quantity and pressure available at all times.

5. Systematic, thorough, and intelligent care and inspection of the system.

=75. Fireproof Windows.=—It is frequently necessary, and in many cases required by law, and especially recommended by the Underwriters, to provide fireproof window frames and sash in walls exposed to great fire risk, or where it is necessary to admit light into elevator shafts or fire-towers. To meet this demand, several forms of metallic window frames and sashes have been evolved, and these sashes when intended as a fire-retarder are always glazed with wired glass.

=76. Wired Glass.=—The wire glass now in common use consists of heavy glass plate with wire mesh embedded in it. This glass is obtainable in polished, ribbed, prism, or mazed form, as shown in Fig. 35 (_a_), (_b_), (_c_), and (_d_), respectively. The plain glass, Fig. 35 (_a_), is used where the light is ample, and where it is desired for the occupants to see through the windows. The ribbed is employed usually in factories, and the ribs are generally run in a horizontal direction, so as to throw the light toward the ceiling and floor, thus diffusing it throughout the building. The prism glass is also employed in order to secure a greater diffusion of the light than is possible with the plain or factory ribbed glass, while the mazed glass finds favor where it is necessary to employ an obscured sash, which will still admit plenty of light and present a good appearance but yet cannot be seen through.

The glass used in metallic frames should not be less than ½ inch, or, if polished, ⁵/₁₆-inch, and the embedded wire should not have a mesh larger than 1 inch and should not be less in size than No. 22 Brown & Sharpe wire gauge, which is the standard used in America.

=77. Design of Sash.=—In designing a sash for fire-retarder frames, it is necessary, in order to comply with the Underwriters rules and regulations, to observe that no single light exceeds 24 in. × 30 in. The metallic frames are generally constructed of No. 22 galvanized steel, while the sash are made of a lighter weight, generally No. 24. In unusual localities, where the frames are likely to be subjected to the influence of gases, with known affinity for iron or galvanizing, it is permissible to make the metallic frames of 18-ounce copper, though such frames are not considered the equivalent of an iron frame as a fire-retarder, and such frames should never be used in elevator, vent shafts, or fire-retarder partitions that are liable to intense internal fires.

In order to better explain the construction of the commercial frames, Fig. 36 is given, which illustrates one of the best frames in the market. In the figure, a vertical cross-section through the window-head sill and parting rail is illustrated. It will be observed that these frames can be neatly framed with architrave mold and stop, as designated at _a_ and _b_. It will also be observed that the head for the top sash is beveled, as indicated at _c_, so that a tight joint is insured by the edge of the sash coming in contact with the bevel, and thus compelling a close connection. The parting rails are also constructed with a straight piece entering on a bevel _d_, so that at this point a tight joint is also secured. By the several offsets in the sill, wind and rain stops are provided, as indicated at _e_. Sashes constructed in this manner can be made to slide freely, noiselessly, and be made tight against weather and wind, as well as being secured against annoying clattering, or rattling. The sills of metallic frames are generally filled with cement, and sometimes the heads are similarly made solid. Any unusually large surfaces, like that which would occur between twin or triple windows, in the mullion, are securely braced inside with galvanized sheet iron or bar iron.

=78.= In the construction of metallic sash, solder is never used for holding the parts together, for all parts must be either lock-seamed or riveted, the lock seams being illustrated at _g_, Fig. 36. Soldering may be used only to fill up the joints. The objection to a joint that is only soldered and not lock-seamed is that in a severe fire when the window is subjected to an intense heat, the joint is apt to open by the solder melting out. When the joint opens, flames may go through and the fire-stop will thus be soon destroyed.

In designing the frames, they should have at least a 4-inch lap on the brick reveal on the sides and head, and it is not uncommon to wind-stop the sill by extending upwards a piece of galvanized sheet iron. While such windows as those described will act as a fire-retarder and prevent flames from reaching apartments that they protect, even in cases of severe conflagrations, nevertheless the glass radiates considerable heat, and inflammable goods should not be stored too close to such windows. Neither is it particularly desirable to have window shades secured to the frames of metallic windows. Where the goods in a building are particularly inflammable, the liability to pile them too close to the sash should be entirely eliminated by using window guards, which would maintain such merchandise at a distance of 3 or 4 feet from the window.

=79. Fire-Doors and Frames.=—There is no more important feature in the design of a mill building than the tin-lined fire-doors and their attachment to the jambs. Every fault in their construction, as viewed by the Underwriters, is likely to cost the owner additional insurance.

All tin-lined doors, when one door is used, should be made of three thicknesses of tongued-and-grooved planking, laid up and down and horizontally, and clinched-nailed, as illustrated in Fig. 37. The tin lining on these doors must be of IC tin, put together with locked seams, secretly nailed, and presenting the appearance designated in Fig. 38.

=80.= The sills of openings covered with tin-lined doors must always project under the door, so that there is no danger of burning through the floor and thus communicating to the space protected by this entrance. The several constructions of sills most commonly used are illustrated in Fig. 39.

=81.= Sliding-doors should be hung with anti-friction adjustable hangers. That is, the wheel of the hanger should have roller bearings for the axle, and there should be some means of adjusting the height of the door above the threshold by means of the hanger. The track for sliding-doors should be placed on a slant toward the opening, so that the door will automatically close. Where it is desired to have the door open, it may be held back by means of a chord, fusible link, and counterweight.

=82.= All folding doors should be heavily strap-hinged, and secured to the jambs with iron-hanging stiles and hinge eyes with through bolts, as shown at _a_, Fig. 40.

Care must always be taken that any through bolts that go through brick walls near door openings, as the bolts shown at _a_, Fig. 40, be far enough away from the jambs so that there will be no danger of the bolts pulling through when put under strain. It is always better to build these bolts in the wall as the work progresses than to drill holes and put them in afterwards.

INDEX

NOTE.—In this volume, each Section is complete in itself and has a number. This number is printed at the top of every page of the Section in the headline opposite the page number, and to distinguish the Section number from the page number, the Section number is preceded by a section mark (§). In order to find a reference, glance along the inside edges of the headlines until the desired Section number is found, then along the page numbers of that Section until the desired page is found. Thus, to find the reference “Anchors, Screw, §55, p16,” turn to the Section marked §55, and then to page 16 of that Section.

A Allowance for hardware, §55, p147 Anchors, Screw, §55, p16 Application of hardware, §55, p151 Arches, Cost of terra-cotta floor, §60, p35 Ash disposal in factories, §64, p42 Ashlar, §61, p6 and cut stone, Cost of, §60, p26 Cost of, §61, p6 or cut stone, Estimating cost of, §60, p28 Asylum and prison locks, §55, p64 Automatic sprinkler system in factories, §64, p53

B Bank and safe locks, §55, p66 Barb nails, §55, p9 Barbed dowel-pin, §55, p10 Base plates, §64, p13 Baseboards, rails, and moldings, Cost of, §60, p67 Beams and girders, Concrete, §64, p26 and girders in mill construction, §64, p34 Blind and shutter hinges, §55, p38 Blocks, Cost of concrete building, §60, p23 Board measure, §60, p38 Boiler room in factories, §64, p41 -room planning in factories, §64, p41 Bolts and screws, §55, p11 Casement, §55, p93 Chain, §55, p110 Cremorne, §55, p95 Door, §55, p108 Espagnolette, §55, p96 Expansion, §55, p14 Bolts, Flush, §55, p11 Foot, §55, p110 Indicator, §55, p123 Shutter, §55, p130 Special, §55, p17 Transom, §55, p93 Brads, §55, p9 Flooring, §55, p9 Brass and bronze butts, §55, p9 and bronze door knobs, §55, p72 Brick, Common, §61, p9 Pressed, §61, p8 Table of labor prices per thousand, §60, p34 Brickwork, §60, p31 Calculating quantities for, §61, p8 Cost of, §60, p32 Cost of common, §61, p10 Cost of pressed, §61, p9 Estimating, §60, p33 Bridging, §61, p14 Bronze and brass door knobs, §55, p72 Builders’ hardware, §55, p1 Building blocks, Cost of concrete, §60, p23 Data on cost of reinforced-concrete, §60, p20 per cubic foot, Table of cost of, §60, p3 per square foot, Cost of framing and covering of, §60, p41 Summary of cost of, §61, p44 Butts and hinges, §55, p24

C Cabinet hinges, §55, p132 locks, §55, p64, p136 Calculating number of studs, §60, p39 quantities for brickwork, §61, p8 quantities for carpentry work, §61, p10 quantities for excavations, §61, p2 quantities for gas-fitting, Estimating and, §61, p40 quantities for heating and ventilating system, Estimating and, §61, p35 quantities for joinery, §61, p23 quantities for lathing and plastering, §61, p22 quantities for painting, Estimating and, §61, p42 quantities for plumbing system, Estimating and, §61, p37 quantities for roofing, §61, p21 quantities for stonework, §61, p4 quantities, Scope of subject of estimating and, §60, p1 quantity of nails required, §60, p45 sheathing or rough flooring, §60, p40 the volume of an excavation, §60, p16 Care and maintenance of locks, §55, p69 Carpenter, Work per day of, §60, p42 Carpentry, §60, p38 Cost of, §61, p21 Table of cost of miscellaneous items of, §60, p45 work, Calculating quantities for, §61, p10 Casement adjusters, §55, p99 bolts, §55, p94 Casing nails, §55, p9 Cast-iron door knobs, §55, p71 -iron hinge butts, §55, p27 -iron sash weights, §55, p18 Catches, Cupboard, §55, p133 Elbow, §55, p134 Ceiling, Cost of yellow-pine, §61, p20 Yellow-pine porch, §61, p20 Cellar excavations, §61, p2 floors, Cost of cement, §60, p23 stairs, §61, p30 Cement cellar floors, Cost of, §60, p23 Centers, Sash, §55, p88 Chain bolts, §55, p110 Door, §55, p107 fastener, §55, p107 Chains, Sash, §55, p81 Transom, §55, p93 Chimneys, Construction of brick, §64, p49 Factory, §64, p45 Stability of brick, §64, p47 Table of capacities of, §64, p46 Chipped glass, §55, p158 Classification of factory buildings, §64, p2 Clinch nails, §55, p10 Coal storage in factories, §64, p42 Column footings, §64, p28 Columns, Strength of concrete, §64, p24 Strength of reinforced-concrete, §64, p25 Combination locks, §55, p67 Concrete, Advantages of reinforced, §64, p24 beams and girders, §64, p26 building blocks, Cost of, §60, p23 buildings, Data of cost of reinforced-, §60, p20 columns, Strength of, §64, p24 factory buildings, §64, p23 footings, §64, p14 footings and floor, §61, p7 footings, Cost of, §61, p7 Table of cost of plain gravel, §60, p19 Table of cost of plain stone, §60, p19 walls supporting cranes, §64, p39 window heads, §64, p27 work, Plain, §60, p18 work, Reinforced-, §60, p18 Construction of brick chimneys, §64, p49 Slow-burning, §64, p18 Types of mill, §64, p13 Contractor’s method of figuring excavation, §60, p14 Corner and strap hinge plates, §55, p44 Cornice, spandrels, etc., Cost of, §61, p20 Cornices, Measuring of, §60, p41 Cost of ashlar, §61, p6 of ashlar or cut stone, §60, p26 of ashlar or cut stone, Estimating, §60, p28 of baseboards, rails, and moldings, §60, p67 of brickwork, §60, p32 of building, Summary of, §61, p44 of buildings per cubic foot, Table of, §60, p3 of carpentry, §61, p21 of cement cellar floors, §60, p23 of common brickwork, §61, p10 of concrete building blocks, §60, p23 of concrete footings, §61, p7 of cornice, spandrels, etc., §61, p20 of ditch work, Estimating the, §60, p15 of door frames and doors, §60, p65 of electric wiring, §61, p41 of excavation, §61, p4 of excavation, Actual, §60, p12 of flagstones and curbing, §60, p26 of flooring, §61, p19 of framing, §61, p17 of framing and covering of building per square foot, §60, p41 Cost of gas-fitting, Estimates and, §60, p72 of granite, §60, p29 of gravel roofs, §60, p54 of hardware, §61, p35 of heating and ventilating system, §61, p37 of joinery, §61, p33 of labor for gas-fitting, §61, p41 of labor for installing plumbing system, §61, p40 of lathing, Measurement and, §60, p60 of laying wooden floors, Table of labor and, §60, p44 of mackite, §60, p38 of miscellaneous interior joinery, §61, p32 of miscellaneous items of carpentry, Table of, §60, p45 of molding, §60, p62 of painting, §60, p75; §61, p43 of paneling and wainscoting, §60, p67 of plain gravel concrete, Table of, §60, p19 of plain stone concrete, Table of, §60, p19 of plastering, §60, p59; §61, p23 of plumbing, Approximate, §60, p70 of plumbing system, §61, p40 of pressed brickwork, §61, p9 of reinforced-concrete floor slabs, Table of, §60, p22 of roof tiling per square, Table of approximate, §60, p53 of roofing, §61, p22 of rubble masonry, §60, p25; §61, p5 of sheathing and shingles, §61, p18 of slating per square, §61, p21 of slating per square, Table of approximate, §60, p51 of soft stone, §60, p28 of stairs, §60, p67; §61, p31 of structural steel, §60, p69 of terra-cotta floor arches, §60, p35 of terra-cotta partitions, Table of, §60, p36 of tiling, §60, p37 of verandas, §60, p68 of window frames and windows, §60, p63 of yellow-pine ceiling, §61, p20 Covering, Kinds of roof, §60, p46 of building per square foot, Cost of framing and, §60, p41 Cranes on concrete walls, §64, p39 Planning for traveling, §64, p37 Cranes, Track construction for traveling, §64, p39 Cremorne bolts, §55, p95 Cubic foot, Table of cost of buildings per, §60, p3 Cupboard buttons, §55, p134 catches, §55, p133 latches, §55, p132 Curbing, Cost of flagstones and, §60, p26 Cut nails, §55, p2 nails, Table of sizes of, §55, p6 stone, §61, p6 stone, Cost of ashlar and, §60, p26

D Designs of hardware, Stock and commercial, §55, p22 Dimension stone, §60, p24 Dimensions of factory chimneys, §64, p45 Ditch work, Estimating the cost of, §60, p15 Door bolts, §55, p108 chains, §55, p107 checks, §55, p111 frames and doors, Cost of, §60, p65 frames, Attic, §61, p24 frames, First-floor, §61, p24 frames, Second-floor, §61, p24 hangers, §55, p114 holders, §55, p105 knobs, §55, p70 knobs, Brass and bronze, §55, p72 knobs, Cast-iron, §55, p71 knobs, Sizes and styles of, §55, p73 knobs, Spun-metal, §55, p73 knobs, Stamped, §55, p72 knobs, Wooden, §55, p71 knockers, §55, p121 Korelock, §60, p66 locks, Interior, §55, p50 pulls, §55, p102 -screen latches, §55, p124 springs, §55, p111 stops, §55, p105 trims for water closets, §55, p123 Doors, Attic, §61, p26 Cost of door frames and, §60, p65 Elevator, in factories, §64, p8 Fireproof, §64, p57 First-floor, §61, p25 Second-floor, §61, p26 Double-acting hinges, §55, p33 -door locks, §55, p57 Dowel-pin, Barbed, §55, p10 Drainage system, §61, p39 Drainage system, Estimates for, §60, p70 Drawer pulls, §55, p135 Drive screws, §55, p13