Reading a fitting tells the size of its inlet, outlet, and branch. A reading procedure has been established by the plumbing trade to assure that there is a standard to go by.

The following "rules" will give you a good idea of how to read a fitting:

1. Elbows are fairly simple; they are full size or reducing. Tees and wyes are a little different; they have an inlet, outlet, and branch. Look at Figure (b) below; see the inlet labeled A, the outlet labeled B, and the branch labeled C.
2. If the inlet, outlet, and branch sizes are of the same diameter, you need only read the one size. Example, a ¾” elbow has a ¾” socket on both ends. A 2” tee would have 2” sockets at all three openings.
3. If an elbow has two different diameters, it’s called a “reducing elbow.” Read the larger diameter socket first, then the smaller diameter socket. Example: a 1” x ¾” reducer ell would have a 1” socket and a ¾” socket. See (a) on the illustration.
4. When reading tees and wyes, read the larger socket first, and the straight through socket next. Then, read the branch diameter. Refer to view (b).
5. If the first and second sockets on a tee or wye have the same diameter, you need only state the size once, as shown in views (c) and (d). If the second socket and the branch are the same size, you must still identify the size separately, as shown in (e).
6. If the branch size is larger than the size of the first and second sockets, the fitting is called bullheaded. You must still read the fitting according to Rule 3 above.