Penlon AV-S, Service Manual, Page: 37 / 94

DESCRIPTION - O
2
Monitor
3.12 Oxygen Monitor
The oxygen monitor continuously measures and indicates
the concentration of oxygen in the breathing system, and
triggers an alarm when the concentration varies from the
set levels.
3.12.1 System Description
The Oxygen Monitor uses a fast-responding, oxygen-
specific, self powered sensor that achieves 90% of final
value in less than 10 seconds.
An external probe (1) is supplied with a 2 m (6 ft)
extendable cable.
The system has user-adjustable high-level and low-level
alarms with visual and audible indication of alarm
conditions.
Bacterial Filter
Use a breathing system bacterial filter in the
expiratory limb of the breathing circuit to protect the
oxygen sensor (see section 5 in the AV900 or AV-S
user manual).
CAUTION
Replacement/Disposal - always follow the instructions
supplied with the filter, and always replace at the
recommended interval.
3.12.2 The MOX-3 Oxygen Sensor
The MOX-3 oxygen sensor offers quick response, linear
output over the entire 0-100% oxygen range, and long
service life.
The MOX-3 is a self-powered galvanic cell that generates
a current proportional to oxygen concentration.
The cell has a highly stable output over its operating life.
Significant output loss is only shown at the very end of its
life.
Typical sensor drift rates are less than 1% per month when
the sensor is exposed to gas in typical applications.
Sensor life:
approximately 1500 000 O
2
percent hours at 20
o
C
(minimum one year in most normal applications).
Sensor lifetime is governed by the mass of lead available
to react with the oxygen and its rate of consumption. High
oxygen partial pressure and high temperature will increase
the sensor output current, thus shortening the operation
life.
At the point where all lead has been consumed, the output
will fall very quickly to zero over a period of two to three
weeks.
31
O
2
Sensor Location
Prima SP with A200SP Absorber
1