PLUMBING VALVES AND ACCESSORIES
LEARNING OBJECTIVE: Recognize types of valves, accessories and their use,
methods of installation, maintenance, and repair.
In this chapter, you are provided information
regarding types of valves and procedures for installing
and repairing them, valve accessories, and pipe
fittings. Also discussed are testing of systems, erecting
shoring and scaffolding, and laying out wastewater
systems, and water distribution systems.
LEARNING OBJECTIVE: Recognize types of
valves and methods of valve repair.
Flexibility in the operation of a water-supply
system requires the proper valves for the condition that
is to be controlled. Valves are used to stop, throttle, or
control the flow of water in a pipeline. Other uses
include pressure and level control and proportioning
flow. A number of different valve designs are used by a
Utilitiesman. In this section, different types of valves,
their purpose, and maintenance and repair of valves are
The gate valve (fig. 4-1) is used in systems where a
straight flow with the least amount of restriction is
needed. These valves are used in steam lines,
waterlines, fuel oil lines, and fire-main cutouts.
The part of a gate valve that opens or closes the
valve flow is known as the GATE. The gate is normally
wedge-shaped; however, some are uniform in
thickness throughout. When the gate is wide open, the
opening through the valve is equal to the size of the
piping in which the valve is installed; therefore, there
is little resistance in the flow of the liquid. Since
regulating the flow of liquid is difficult and could
cause extensive damage to the valve, the gate valve
should NOT be used as a throttling valve. The gate
valve should be left in one of two positions-
completely open or closed.
Figure 4-1.Gate valve.
Figure 4-1 shows a cross-sectional view of a gate
valve. The gate is connected to the valve stem. Turning
of the handwheel raises or lowers the valve gate. Some
gate valves have NONRISING STEMS. On these, the
stem is threaded on the lower end, and the gate is
threaded on the inside; therefore, the gate travels up the
stem when the valve is being opened. This type of
valve usually has a pointer or a gauge to indicate
whether the valve is in the OPEN or in the CLOSED
position. Some gauge valves have RISING STEMS. In
these valves, both the gate and the stem move