Chapter 6 Cooling Water
System
_5_.
P_re_s_s_u_re_C_a_p_a_n_d_S_u_b_T_a_n_k
______________________
3,4JH3(B)(C)E
5.
Pressure Cap and Sub Tank
5-1
Pressure cap construction
The pressure cap mounted
on
the fresh water filler neck
incorporates a pressure control valve. The
cap
is
mounted
on
the
filter neck
cam
by placing
it
on
the rocking tab and
rotating. The top seal of the cap seals the top of the filler
neck, and the pressure valve seals the lock seat.
5-2 Pressure cap pressure control
The pressure valve
and
vacuum
seal
both
seal
the
valve
seat when the pressure
in
the fresh water system
is
with-
in the specified value of 0.9kg/cm
2
•
This seals the fresh
water system.
When the pressure within the fresh water system exceeds
the specified value, the pressure valve opens, and steam
is
discharged through the overilow pipe. When the fresh
water
is
cooled and the pressure within the fresh water
system drops below the normal value, atmospheric
pressure opens the vacuum valve, and air
is
drawn
in
through
the
overflow pipe.
Pressure
valve
spring
Overflow
pipe
\
_______
\\\
~[ITCJ
The sub tank {which will be described later), keeps the
water level from dropping due to discharge
of
steam when
the pressure valve opens.
Action
of
pressure control valve
Pressure
valve
Open
al
0.9
kg/cm'
Vacuum
valve
Open
at
0.05
kg/cm'
or
below
6-10
5-3 Pressure cap inspection
Precautions
Do
not open the pressure cap while the engine
is
running
or right after stopping because high temperature steam
will
be
blown out. Remove the cap only after the water
has had a chance to cool down.
(1)
Remove scaie and rust, check the seat and seat valve,
etc. for scratches or wear, and the spring for corrosion
or settling Replace if necessary
NOTE : Clean
the
pressure cap with fresh water as it will
not close completely
if
it
is dirty.
(2)
Fit the adapter
on
the tester
to
the pressure cap. Pump
until the pressure gauge
is
within the specified pres-
sure range (0.75~1.05kg/cm
2
)
and note the gauge
reading. The cap
is
normal
if
the pressure holds for
six seconds
If
the pressure does not rise, or drops
immediately, inspect the cap and repair
or
replace as
necessary.
Parts No. of cap tester
i
20445-44600
5-4 Function
of
the sub tank
The pressure valve opens
to
discharge steam
when
the
steam pressure
in
the
fresh water tank exceeds 0.9kg/cm'
(12.80lb/in.').
This consumes water. The sub tank maintains the water
level
by
preventing this discharge of water.
The steam discharged into the sub tank condenses into
watch, and the water level
in
the sub tank rises.
When the pressure in the fresh water system drops
below the normal value, the
water
in
the
sub tank is
sucked back into the fresh water tank to raise the water
back to its original level.
The sub tank facilitates long hours of operation without
water replacement and eliminates the possibility of burns
when the steam
is
ejected from the filler neck because the
pressure cap does not need to
be
removed.
Printed in Japan
HINSHI-118009
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