Figure 4-17.—Limitorque valve operator.
limiting the torque and thrust loads applied to the
valve. It also provides a constant seating thrust, thus
assuring the valve is tight on each closure. This seat-
ing thrust can be varied by a fine adjustment on the
torque limit switch. The torque limit switch operates
and disconnects the source of motive power should an
obstruction be met while the valve is being closed.
Limit switches on the limitorque govern valve
disk travel in the opening and closing directions of
valve stem travel. The switches also operate position
indicator lights for both the open and closed position
of the valve. In case of motor failure, the limitorque
unit can be operated manually by use of the hand-
wheel. To prevent accidental operator injury, a motor
declutch mechanism disengages the handwheel when
the motor is energized.
Limitorque valves may be used in the following
areas:
— Valves in manifolds serving JP-5 storage tanks
— Valves for filling JP-5 service tanks
— Valves taking suction from JP-5 service tanks
— Selected cut-out valves in all three sub-systems
— Selected valves in the drainage and ballast system
To the ABF, the limitorque valve operator is a
valuable asset as long as it is operating and used
correctly.
Swing Check (One-Way) Valves
Swing check valves (fig. 4-1 8) are designed to
prevent back flow by allowing fluid transfer in only
one direction in the piping systems.
Figure 4-18.—Swing-type check valve.
4-21
