Figure 8-30 shows the symbols used for the most frequently encountered valves. The type of material and size of valves are normally not noted on mechanical drawings but must be assumed from the size and material of the connected pipe.

Figure 8-30.-Valve symbols.

However, when specified on the lists of materials or plumbing takeoff, valves are called out by size, type of material, and working pressure; for example, 2-in. gate valve, PVC, 175-lb working pressure.