(2) Compression-type fittings. These fittings (fig 8), also known as
flared fittings, are used only with flexible copper tubing. Their principal use is
in air piping and in fuel oil lines because they resist vibration better than
solder-type fittings. For general plumbing, they are not recommended for
connections to be sealed in walls.
a. Definition. A valve is a device used to stop, start, or regulate the flow
of a liquid or gas into, through, or from pipes. It usually is made of brass. The
body of the valve has an opening and a way of closing the opening with a valve disk
or plug which can be tightly pressed against a seating surface around or within the
Only a few of the many types are discussed here.
(1) Gate valve. The gate valve (1, fig 9) has a wedge-shaped movable gate
which closely fits the movable seat when the valve is closed. When the valve is
open, the gate clears the opening formed by the seat and allows a straight line
passage for the flow. To limit wear on the gate and seat, gate valves should be
used on lines which remain either completely open or shut most of the time. The
valve shown is a rising stem, single disk, gate valve. Other common types are the
double disk and the nonrising stem.