is the lever operated switch. It is activated by a
physical arrangement of some tanks makes this
horizontal lever attached to a float. The float is
necessary. When multiple sections are used, they
located inside the tank. When the liquid level
are electrically connected as one continuous
reaches a preset point, the lever activates the
divider network.
switch.
Two types of floats are used. In noncompen-
The other type of level switch uses a magnet-
sated tanks, the float is designed to float at the
equipped float sliding on a vertical stem. The stem
surface of the fuel or JP-5. For seawater
contains a hermetically sealed, reed switch. The
compensated tanks, the float is designed to stay
float moves up and down the stem with the liquid
at the seawater/fuel interface.
level. It magnetically opens or closes the reed
switch as the float passes over it. Figure 5-23
shows the construction of the magnetically
CONTACT LEVEL SENSORS
operated float switch. Magnetic float switches
may be constructed with more than one float on
Many times you do not have to know the exact
a stem. This type of switch can detect multiple
level of a tank until it reaches a preset level. When
levels in the same tank, such as a high- and low-
this type of indication is needed, you can use a
level alarm. You may also wire multiple stems
contact or float switch. Two types of float level
together to provide this same feature.
switches are used on gas turbine ships. One type
Figure 5-23.--Magnetic float switch.
5-18
