DeVilbiss DeVO/MC44-90 - Normal Cycling Sequence of DeVO;MC44

SECTION 7
SERVICE INSTRUCTIONS
2. Refer to Service Instruction B to open
front cover.
3. Disconnect the termina! connectors at
end of wire harness (12 Fig. 12) from the
MC board by pulling them straight out.
4. Remove the 1/16” (1.6 mm) hose attached
to the transducer (14 Fig. 12).
5. Remove the four screws (6 Fig. 12) that
secure the board to the cabinet and
remove the MC board.
6. Install the new MC board and secure it
using the four screws.
7. Reconnect the terminal connectors and
transducer hose.
8. Close front cover and secure with cabinet
fasteners.
. Normal! Cycling Sequence of DeVO/MC44
When pressure test gauges are attached to
the test points (Fig. 22) on the manifold the
following cycling sequence should be
observed. Most types of unit malfunctions will
cause a deviation in this sequence and
possibly a unit shutdown or a change in cycle
times.
When the concentrator is turned on, this
normal cycling sequence should be observed.
A. Right sieve bed is pressurized (approxi-
mately 26 PS! (179 KPa)) and left sieve bed
is depressurized.
1. Four-way valve is activated.
a. Pilot pressure is entering four-way
(approximately 22-28 PS! (152-193
KPa)).
b. A 12-15 VDC signal from MC
board is present at terminals on
pilot valve and the green four-
way indicator light is illuminated.
B. Purging action is present (approximately
1.0 seconds) and bed pressures equalize at
approximately 15 PSI (103 K Pa).
1. Purge valve is activated.
a. Pilot pressure is entering purge
(approximately 22-28 PS! (152-193
KPa)
b. A 12-15 VDC signal from MC
board is present at terminals on
pilot valve for approximately 1.0
10/87
24
seconds and the green purge
indicator light is illuminated.
C. Left sieve bed is pressurized (approxi-
mately 26 PSI (179 KPa)) and right sieve
bed depressurizes to 2 PSI (13.8 KPa).
1. Four-way valve is deactivated.
a. The pilot valve shuts off pilot
pressure to four-way.
b. No voltage is present at terminals
of pilot valve and the green four-
way indicator light is not illum-
inated.
D. Purging action is present as described in
step B.
E. Step Ais repeated again.
NOTE: Cycle time is approximately 11
seconds for each sieve bed at 2 LPM.
However increases in altitude and flow rate
will increase cycle times slightly and
decreases will shorten cycles.