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SECTION 7
SERVICE INSTRUCTIONS
body and valve manifold should also be
removed.
2.
Remove the 4 screws from the ends of the
valve
so that the
end
plates,
plastic
spacers and spring can be removed. Note
position of these parts.
3.
Carefully remove spool from valve body.
Using a non-metallic rod or dowel with a
diameter
no
greater
than
the
sleeve,
slowiy push the sleeve out either end of
the valve body. (Note: Pushing too fast
will cause o-rings to roll and jam).
Remove the "O" rings from the sleeve and
inspect them for signs of damage. If they
are damaged,
they should
be replaced
using valve rebuild
Kit #MC44D-707 prior
to reinstallation of the sleeve into the
valve body.
5.
Wash the spool and sleeve (less "O" rings)
in warm,
soapy water
until all of the
deposits have been removed. The plastic
spacers and spring may also be cleaned if
needed. (Important: Never try to scrape
the spool or sleeve or use an abrasive
substance
for
cleaning.
This
would
adversely affect the operation
of the
valve). Reinstall or replace "O" rings on
sleeve.
6.
Rinse the spool
and sleeve thoroughly
and dry with a soft, clean lint-free cloth.
7.
Ensure that the air passages (ports)
in
both the valve body and manifold are free
of any foreign matter. A clean lint-free
cloth or a compressed
air hose can be
used to clean these.
8.
Carefully push sleeve
into valve
body
(turning it slightly) so you do not cut or
knick
the o-rings.
To
ensure
proper
placement
of spool,
use white
plastic
spacer and push until spool is flush with
valve body.
9.
Reassemble
remaining
parts of valve in
reverse order.
To replace purge valve:
1.
Align valve body and gasket on manifold.
Ensure that gasket is aligned properly.
Secure with two allen head screws.
Attach pilot pressure tubing to pilot valve.
Reconnect the two wires on terminals of
pilot valve.
19
4.
Replace the cabinet covers and
secure
with cabinet fasteners.
Compressor
The DeVO/MC44 uses a double head, oil free,
Thomas compressor (14 Fig. 14) to pressurize
the system up to a maximum
of 28 PSI (193
KPa) every cycle. It is secured to the base of
the unit by four rubber motor mounts (13 Fig.
14).
A defective compressor will cause longer cycle
times resulting in lower oxygen
concentra-
tions. Long cycle times will activate the alarm
system when the maximum
pre-set cycle is
exceeded. In this case, the red long cycle light
will illuminate. See Section 5, Alarm System.
A compressor that is worn or defective may
cause excessive noise and/or vibration. It may
also result in a reduced
pressure
output.
Usually this is caused by a defective internal
component
such as a reed
valve,
o-ring,
gasket, or teflon ring. These
components
(except the teflon ring) are included
in the
compressor service kit (21 Fig. 26), Part #955-
566.
NOTE: These internal components should be
inspected and changed
if necessary at ap-
proximately 10,000 hours of unit operation.
A built-in thermal cutoff switch will shut the
compressor off if it becomes overheated. This
protects the compressor from damage caused
by a heat build-up.
To test compressor voltage:
A 240 VAC is required to operate the com-
pressor. If the compressor does not start when
power is turned on, the voltage input must be
tested. This voltage can be checked
at the
compressor connector using a volt meter or
test light. (See Figure 18).
İf no voltage is detected check for loose or
broken wires between the compressor con-
nector and MC board. If the wiring is good,
replace the MC board. If there is voltage at
the compressor connector then
either the
capacitor or compressor itself is defective.
To test the compressor for proper output:
Testing the compressor
involves
both
the
testing of the pilot pressure and
sieve bed
pressures. First, test for pilot pressure. See
Service Instruction "J". If pilot pressure is low
or rising slowly, test sieve bed pressures. If it is
also low or rising slowly, then:
10/87
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