
Unit I: Legends,
MEASURING PIPE RUN LENGTHS 1. A plumber is often required to make a list of plumbing materials from a construction drawing or a set of construction drawings. The list must contain all the materials by type, size, and length to install a part of or the complete plumbing system. 2. Horizontal pipe run lengths are measured using either graphic or ratio construction scales. a. To make graphic scale measurements with a divider, first spread the divider from the center of one fitting to the center of the next fitting to get the length of the pipe run (fig 21). Then place one end of the divider on 0 (fig 22). Where the other end falls on the scale is the pipe run length. FIGURE 21. DIVIDER ON DIAGRAM FIGURE 22. DIVIDER ON SCALE b. To make graphic scale measurements with the straightedge of a piece of paper, place the straightedge along the pipe run and mark the center of each fitting (fig 23) on the paper. Then place one mark on 0 (fig 24). Where the other mark falls on the scale is the pipe run length. FIGURE 23. STRAIGHTEDGE ON DIAGRAM FIGURE 24. STRAIGHTEDGE ON SCALE c. To make ratio scale measurements with a ruler, place the zero of the ruler at the center of one fitting and the measuring edge along the pipe run. Read the ruler mark at the center of the other fitting. See figure 25. If the ratio scale is 1/4 inch = 1 foot, the reading of 1 5/8 inches on the diagram means 6 feet 6 inches of pipe. FIGURE 25. USE OF RULER WITH RATIO SCALE 3. Vertical waterpipe lengths are computed using simple math. The pipe run can come down from the ceiling level or up from below the floor level. a. To determine a pipe run length from the ceiling level, use the floortoceiling measurement, the distance the pipe hangs from the ceiling, and the fixture's roughin measurements. To find the length of pipe X in figure 26, make the following computation: Floor to ceilings  7 feet 11 inches. The length of pipe X is 3 feet 3 inches FIGURE 26. PIPE RUN FROM CEILING b. To find a pipe run length from below floor level to ceiling, use the floortoceiling measurement, the distance the pipe hangs from the ceiling, and the distance the pipe is below the floor. To find the length of pipe Z in figure 27, make the following computation: Floor to ceiling  7 feet 11 inches. The length of pipe Z is 8 feet 1 inch: FIGURE 27. PIPE RUN FROM BELOW FLOOR TO CEILING c. To find a pipe run length from below floor level to a fixture, use the distance the pipe hangs below the floor and the fixture's roughin measurements. To find the length of pipe Y in figure 28, make the following computation: Pipe hangs from floor  3 inches. The length of pipe Y is 14 inches. FIGURE 28. PIPE RUN FROM BELOW FLOOR TO FIXTURE 1. Use the graphic scale given in figure 29. What is the length, in feet, of line X? FIGURE 29. USE OF GRAPHIC SCALE Did you get 7 1/2 feet? If not, read Lesson 1, paragraph lb, again. If you did get 7 1/2 feet, good work. Continue with the lesson. 2. Use the ratio scale in figure 210. What is the length, in feet, of line Z? FIGURE 210. USE OF GRAPHIC SCALE Did you get 8 feet? If you did, good work. Continue with the lesson. If not, read Lesson 1, paragraph lb, again until you understand ratio scales. 3. Refer to figure 211. Compute the length of pipe Z. FIGURE 211. MEASUREMENT OF PIPE How did you do? Did you get 3 feet 8 inches for the length of pipe Z? Let's see how we got this answer. Floor to ceiling  8 feet 0 inches. Therefore, the length of pipe Z is 3 feet 8 inches. If you have any problems with this computation, study the example closely. Get your squad leader or platoon sergeant to assist you if you need additional help. Then continue with the lesson. 4. Vertical wastesystempipe lengths are computed in the same way as vertical water pipe. a. To find a wastepiperun length from below the floor level to a fixture, use the distance from the center of the bend to the floor and the fixture's roughin measurements. To find the length of pipe needed in figure 212, make the following computation: Bend to floor  6 inches. The length of pipe required is 23 inches. FIGURE 212. VERTICAL WASTEPIPE b. To find a wastepipe length from below the floor up through the roof, use the total of all measurements from the bend below the floor toVTR. To find the length of pipe needed in figure 213, make the following computation:
The length of waste pipe required is 10 feet 21 inches or 11 feet 9 inches. FIGURE 213. VERTICAL WASTE PIPE TO VTR Refer to figure 214. Compute the length of the vent through the roof (VTR) shown. FIGURE 214. VTR MEASUREMENT Did you get 12 feet 1 inch? Let's see how we arrived at that answer. If you had any problems with this exercise, look at the drawing again until you understand. Continue with the lesson. 
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