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SECTION 7
SERVICE INSTRUCTIONS
10.
Secure compressor heads with the screws.
To replace compressor:
1.
Remove the intake baffle ( 8 Fig. 14) from
the compressor intake fitting (8 Fig. 25)
and attach it to the intake fitting on the
new compressor.
2.
Inspect rubber motor mounts. Replace if
damaged.
3.
Install
motor
mounts
on
bottom
of
compressor.
Tighten
them
only
"hand
tight".
4.
Place compressor on base assembly with
threaded
rods
at
bottom
of
motor
mounts extending through holes in base.
5.
Reconnect
black
rubber
hose
to
com-
pressor fitting (2 Fig. 25) and secure with
hose clamp.
6.
Reconnect the compressor
quick-connect
terminal (9 Fig. 25).
7.
Turn unit face down
with
compressor
directed upward and install washers and
nuts on motor mounts.
NOTE:
When
tightening
nuts, hold
motor
mount
with
one
hand
to avoid
twisting
rubber mount. A twisted motor mount may
cause excess vibration or noise.
8.
Reconnect
compressor
intake
hose
(11
Fig. 14) to intake baffle (8 Fig. 14).
9.
Replace cabinet covers.
Ensure that all
quick-connect
terminals
are
properly
connected
before securing covers with
cabinet fasteners.
Pilot Pressure System
The compressed
air in the
pilot pressure
system is used to activate the four-way and
purge valves. This compressed
air (approxi-
mately 22-28 PS! (152-193
KPa))
is stored
in
the
pilot accumulator
cavity
within
the
manifold (1 Fig. 20). An internal check valve
allows compressed air to enter and prevents it
from
escaping. The
inlet side of the pilot
accumulator
is connected
internally within
the
manifold.
The
outlet
of the
pilot
accumulator cavity is connected to the pilot
valves
on
the
purge
and
4-way
by
an
externally mounted "T" fitting and 1/16" (1.6
mm) tubing.
A
defective
check
valve
in the
pilot
accumulator
or leak in the pilot pressure
21
tubing would result in lower pilot pressure.
This, in turn, could cause a malfunction of the
four-way and/or purge valve.
To test pilot pressure:
1.
Refer to Service Instruction
B to open
cabinet covers.
2.
Remove the pilot pressure tubing from
the pilot valve on the four-way (4 Fig. 23).
3.
Attach the pilot pressure tubing to the
barbed fitting on one end of the pressure
test assembly (3 Fig. 23) that is included in
the DeVO Service Kit.
4.
Attach
the
1/16"
(1.6 mm)
hose
on
the
other end of the test assembly
to the
fitting on the pilot valve (Point D, Fig. 23).
5.
Install
a pressure
gauge
on
the
test
assembly.
6.
With the unit operating,
pilot pressure
readings should be alternating between
22 to 28 PSI (152-193
KPa). This pressure
range may vary slightly from one unit to
another.
This is essentially
the
same
pressure as that being exhausted
by the
compressor. Therefore, it can also be used
to help determine
if the compressor
is
working properly.
7.
If pilot pressure is low, check sieve bed
pressure.
8.
If sieve bed pressures are normal, check
for leaks in the pilot pressure system. If no
leaks are found, then the check valve in
the pilot accumulator
may
be leaking
internally.
If confirmed,
the
manifold
base must be replaced.
9.
If sieve bed pressures are also low or rising
slowly, then:
(A) Compressor reed valves, teflon ring,
or the
compressor
itself
may
be
defective.
(B) There is a severe leak in system.
(C) One
or more
of unit filters may
be
occluded.
. Manifold Assembly
The manifold assembly is located on the front
of the vertica! divider and has two externally
mounted valves, the four-way and purge (see
Fig.
16).
These
valves
can
be
removed
separately for cleaning or replacement when
10/87
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