Troubleshooting; System Operation; Normal Operating Sequence - DeVilbiss iGo Series Servicehandbuch

TROUBLESHOOTING

System Operation

The DeVilbiss iGo Portable Oxygen System uses a pressure-swing
adsorption system. Air is drawn through filters into a double-head,
pressure-vacuum compressor. The pressure and vacuum created
in the compressor are cycled through a 4-way valve that directs the
pressure to one sieve bed while directing vacuum to the other. A
pressure transducer monitors the accumulator tank and triggers the
valve to direct the pressure/vacuum to the alternate sieve beds
when the tank reaches the specified shift pressure.
The sieve beds contain a synthetically-produced silicate molecular
sieve material with the unique ability to selectively adsorb nitrogen
from the air. As one bed pressurizes and adsorbs nitrogen, the
other bed vacuums forcing the previously adsorbed nitrogen to
exhaust through the valve and an exhaust muffler. During each
pressure-vacuum cycle, a small amount of oxygen from the
pressurizing bed travels to the vacuuming bed through a purge
valve helping to release the nitrogen from the sieve material. The
beds continue to alternately pressurize and vacuum as the unit
operates.
Oxygen leaving each sieve bed travels through a check valve into
the accumulator tank. A pressure regulator on the tank controls the
pressure of the oxygen as it leaves the tank and enters the OSD ®
oxygen sensing device where it is checked for purity. From the
OSD, the oxygen travels to a proportional valve, which adjusts the
flow rate of the oxygen so that the level prescribed by the physician
is delivered accurately. Oxygen leaves the proportional valve and
passes through the final bacteria filter and the oxygen outlet port to
the patient.
The iGo incorporates power efficiency routines. The PC board
adjusts cycle shift pressures and compressor speeds, as needed,
to consume the least amount of power, while maintaining oxygen
delivery with higher than 90% purity levels.
The PC board also activates the electronic alert system. See Alert
System under Maintenance in this manual.
LT-2044
T R O U B L E S H O O T I N G

Normal Operating Sequence

When the concentrator is turned ON @ 3 LPM, the following
cycling sequence can be observed by attaching pressure gauges
to the sieve bed test points.
1. The PC board cycles the 4-way valve quickly several times, to
2. The PC board powers the compressor and sets the
3. The PC board removes voltage from the 4-way and purge
4. When the accumulator tank reaches the shift pressure, the PC
5. The PC board applies voltage to the 4-way valve and removes
6. When the accumulator tank reaches the shift pressure the PC
7. The cycle repeats beginning with step 3.
8
relieve residual bed pressure and prevent a static condition in
the compressor, and opens the proportional valve to relieve
any residual pressure elsewhere in the system. During this
time the PC board conducts a test of the control panel and
audible alerts.
proportional valve to the desired flow rate.
valves. The right bed, as viewed from the front of the unit,
pressurizes while the left bed evacuates to approximately 17
in-Hg.
board applies voltage to the purge valve for 0.8 seconds
sending a small amount of oxygen to the left bed to help
release the nitrogen from the sieve material.
voltage from the purge valve causing the left bed to pressurize
while the right bed evacuates.
board applies voltage to the purge valve for 0.8 seconds
sending a small amount of oxygen to the right bed to help
release the nitrogen from the sieve material.