Quick Disconnect Coupling; Filler Valve - Daewoo G420E Service Manual

Quick Disconnect Coupling

The liquid withdrawal or service valve on a DOT tank
has male threads and accepts the female portion of a
quick disconnect coupling (Figure 8). The female
portion is adapted to the liquid hose going to the fuel
system. Both halves are equipped with 100% shutoffs,
which open when coupled together to allow fuel flow.
The coupler has two seals. One is an o-ring and the
other is a flat washer. The o-ring prevents leakage
from the shaft on the other coupling and the flat
washer seals when the coupler is fully connected.
NOTE
The flat seal and/or the o-ring will
sometimes pop off when disconnecting
and slide up the shaft of the mating
connector, causing the valve not to open
when fully mated. The extra washer or o-
ring must be removed from the shaft and
the coupling reconnected.
Figure 8
Tier
G420E/G424E LP Engine

Filler Valve

The liquid filler valve (Figure 9) has a male thread to
receive a fuel nozzle and typically has a plastic or
brass screw on cap that is retained with a small chain
or plastic band to keep debris out of the filler valve.
The filler valve is a one-way flow device that uses two
check valves to allow fuel to enter the tank but
prevent it from exiting. Both check valves are
backpressure type check valves, designed so that
backpressure from the tank assists the check valves
own spring pressure to close the valve. The first valve
uses a neoprene on metal seal and the second valve
uses a metal on metal seal.
A weakness ring is machined into the filler valve just
above the check valves and will allow the filler valve
to shear off in case of an accident. The valve will
break or shear off above the check valves so that the
tank will be sealed and no liquid propane can escape.
Figure 9
11
Weakness
Ring
MI-04 System Overview