valve functions as outlined above. If the flow rate
suddenly decreases, two things occur:
a. Any pressure rise is offset by the opening
of the defueling valve.
b. The fueling valve closes rapidly.
7. Figure 5-9 shows that delivery pressure is re-
flected under the diaphragm of both pressure-relief
control valves, opposing the force applied by the
spring. When a downstream pressure rise occurs that
is sufficiently high to overcome the force of the
spring, the defueling valve pressure-relief control
valve opens to relieve pressure from the cover of the
defueling valve. This allows the defueling valve to
open, thereby relieving excess pressure into the
defueling line.
8. When pressure and flow conditions return to
normal, all valves resume their normal functions.
Defueling Operation of the Cla-Val
The defueling operation of the Cla-Val follows.
Figure 5-10 shows the valve in the defueling position.
1. The solenoid is deenergized.
Figure 5-10.—Cla-Val defueling operation.
5-7
