Fig. 101.Symbols Used in Piping Diagrams..

In reading plans of buildings, it is usual to have the front of the building, as represented by the plans, next to the person. Plans represent horizontal sections at the elevations designated; while elevations show the altitude of one floor above the other, etc. The plans of the different floors of a building are usually drawn side by side, with the outside face of the front wall on a line. By this means, a straight edge laid across the plans from side to side, will show which partitions are in line with one another. One can judge with the eye, on the cross-partitions, accurately enough to give a good idea of the relative position of the rooms on different floors, one way; but to locate the partitions running from front to back, it is necessary to measure from the wall on the plans of the different floors. House plans are almost always drawn to 1/4-inch scale. In gasfitting diagrams, all sizes of pipe are represented by single or skeleton lines, because the pipes are small.

Now, assuming the plans to be marked for gas, center the rooms, and chalk all wall openings. Then proceed to diagram the lines representing the pipe, making them as nearly proportional to the length of pipe as can easily be done with pocket-rule and pencil, say to 1/4-inch scale.

Represent all vertical pipes by diagonal lines parallel to one another, whether they be bracket pipes, risers, or offsets in the line. Never represent a horizontal pipe by a diagonal line. Every vertical pipe which falls below the horizontal pipe to which it is connected, should be drawn toward the front of the plan at an angle of 45 degrees to the left. Every vertical pipe which rises above the horizontal pipe to which it is connected, should be drawn away from the front of the plan, at an angle of 45 degrees to the right. Represent all horizontal pipes by parallel lines perpendicular either to front or to side wall. When the run of pipe is from front to back, the parallel lines should be perpendicular to the front wall of the building. When the run is from side to side, the parallel lines should be perpendicular to the side wall of the building. Any line in the diagram that is perpendicular to any other line of the diagram may then be taken to represent a horizontal pipe. Any number of lines representing horizontal pipe and all joined together, are thus indicated to be in the same horizontal plane. Any single line or system of lines representing horizontal pipe, but separated from the others by a diagonal line, is therefore in a different horizontal plane. For instance, the second-floor riser, 10 feet 3 inches long, shown in the diagram, Fig. 102, connects the horizontal pipe under the second floor with that under the third floor. These pipes axe in different planes, one set being 10 feet 3 inches above the other.

There is one exception to the rule concerningdiagonal lines. Several feet of pipe can often be saved by cutting across, instead of making an angle with, the pipe. To do this without danger of confusing one as to whether the diagonal piece is intended for vertical pipe or for a diagonal piece in the horizontal plane, make such lines dotted instead of solid, as shown at C, Fig. 102.

To indicate the direction in which bracket openings look, by the way in which they are drawn, eight skeleton diagrams of bracket pipes, showing how the direction of bracket openings would be indicated for the four walls of a square room, are shown in Fig. 103. A,B, C,and D show that the pipes are vertical and run up from the floor below, A looking into the room from the front wall, B from the rear, C from the left side wall, and D from the right side wall. In accordance with plan drawing, the short lines representing the ears and nozzle of the drop-ells are made in plan position with dots at the ends to represent caps. The ears of the fitting, drawn in front of the outlet, show that the fitting looks to the rear; ears behind the outlet show that it looks to the front; at the left of it, that it looks to the right; and to the right of it, that the fitting looks to the left.

Fig. 102. Diagram of Gaspipe Lines..

A1 Bl, C1, and Dl show fittings that look in the same direction as those shown by A, B, C, D of the same figure, but are on pipes that run down from the horizontal pipe. By varying the positions of the marks representing the drop fittings to suit, the diagram can be made to indicate openings pointing in any direction desired.

All large risers should be exposed to view; and it is desirable to keep all piping accessible as far as possible, so that it may be easily reached for repairs if necessary. When it is necessary to trap a pipe, a drip with a drain-cock must be put in; but this should always be avoided under floors or in other inaccessible places. Where possible, it is better to carry up a main riser near the center of the building, as the distributing pipes will then average smaller, the timbers will not require so much cutting, and the flow of gas will be more uniform throughout.

Unless otherwise directed, outlets for brackets should be placed 5 1/2- feet from the floor, except in the case of hallways and bathrooms, where it is customary to place them 6 feet or more from the floor. Upright pipes should be plumb, so that nipples which project through the walls will be level; the nipples should not project more than 3/4 inch from the face of the plastering. Laths and plaster together are usually about 3/4 inch thick, so that the nipples should project about 1 1/2 inches from the face of the studding. Drop- or side-ells are used where possible for bracket openings. Gas pipes should never be placed on the bottom of floor timbers that are to be lathed and plastered, because they are inaccessible in case of leakage or alterations. Fig. 104 illustrates some lines of gaspipe in a frame building, from which may be gleaned graphic ideas of how to fasten pipe securely in place.