Solid and waste pipe BRANCHES are horizontal branch takeoffs that connect various fixtures and the vertical stack (fig. 8-19). One method of installing a branch takeoff from the vertical stack is to use a Y-branch with a 1/8 bend caulked into it. Another method is to use a sanitary tee, which is an extra-short-pattern 900 Y-branch. Of these two methods, the sanitary tee is better because you eliminate one fitting and an extra caulked joint, both of which arc required for the 1/8 bend takeoff.

In some cases, however, the combination Y and 1/8 bend is used more often than the sanitary tee when local codes allow more fixture units to be connected to a stack of a given size.

Generally, waste pipes are graded downward to ensure complete drainage. Horizontal vents are also pitched slightly to facilitate discharge of condensation.

A mechanical plan, as used in this chapter, includes drawings, layouts, diagrams, and notes that refer only to water distribution and sanitary drainage systems. Heating and air conditioning, refrigeration, and other like systems will not be discussed in this section. In the Navy, mechanical systems vary, depending on whether these systems are aboard ship or shore-based. As an EA, you will be mainly concerned with the shore-based systems, which may be permanent installations with the most modern fixtures, equipment, and appurtenances, or temporary installations at advanced bases. For temporary installations, the most economical materials that will serve the purpose are normally used.

The water supply system for a building starts from a single sourcethe water main. Water is tapped from this source with a self-tapping machine (fig. 8-23, view B), and a corporation stop (fig. 8-23, view A) is installed. Cold water enters the building through a cold-water service

line. Figure 8-24 shows typical hot- and cold-water service lines for a single-story residential building and how they are connected to feed the fixtures. This type of layout is often called a RISER DIAGRAM. This diagram, in isometric, is a method of visualizing or showing a three-dimensional picture of the pipes in one drawing.