that other types of valves also may have globe shaped
bodies. Therefore, the name does not always describe
the valve properly.
In a globe valve, the disk is attached to the valve
stem and seats against a seating ring or seating
surface that shuts off the flow of fluid. When the disk
is moved off its seat, fluid can pass through the valve.
Globe valves may be used to limit fuel flow through
the valve (called throttling) by partially opening the
valve to meet the desired flow. Globe valves are most
commonly found on pump discharges, tank mani-
folds, JP-5 purifier discharges, and any other place
where there is a need for throttling fuel flow.
Globe valve inlet and outlet openings are ar-
ranged in several ways and are used to suit the re-
quirements of the flow. There are three common
types of globe valve bodies. In the straight body, the
inlet and outlet openings are in line with each other.
In the angle body, the inlet and outlet openings are at
an angle to each other. The cross globe valve has
three openings instead of two, and is frequently used
in connection with bypass piping.
The high performance butterfly valve (fig. 4-16)
used in the JP-5 system is designed specifically for
flammable liquids or other hazardous materials. If a
fire guts a piping system or space where these valves
are located, and the fire is hot enough to melt a
special sealing element, a secondary metal sealing
takes place providing effective shut-off of fluid flow
through the piping. No feeding of the fire can take
The high performance butterfly valve has a sin-
gle-piece flexible polymeric seat that is pressure ener-
gized to assure positive shutoff. The seat is so
designed that is compensates for pressure and tem-
perature changes as well as for wear. The design also
allows no metal to metal contact during regular
operations. Also contributing to the valves
effectiveness is its offset shaft and eccentric disk
design that impart a camming action to the disk. This
feature causes the disk to swing completely out of
contact with the seat upon opening, eliminating wear
points at the top and bottom of the seat.
This arrangement allows replacement of the
valve seat, if it is ever required, by simply removing
the body insert and then replacing the seat. You do
not have to disassemble the shaft or disk. With no
Figure 4-16.High performance butterfly valve.
requirement to remove the shaft and disk, repair time
is cut dramatically.
As with the gate valve, the high performance
butterfly valve allows fluid flow in either direction.
High performance butterfly valves are normally used
as isolation valves in distribution piping, but they
may be used nearly anywhere.
Limitorque Valve Operators
On newer CVNs, numerous valves have limitor-
que valve operators. Limitorque valve operators (fig.
4-17) open and close gate and globe valves from a
remote location, usually the pump-room console
(which will be discussed later in this chapter).
Each limitorque, in addition to operating a valve,
also controls and limits the opening and closing travel
of the valve. A torque limit switch on the limitorque
protects all operating valve parts from overload by