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OXYGEN CONCENTRATION —
Current oxygen concentration percentage from the oxygen
sensor.
u
HIGH ALARM INDICATOR —
High alarm symbol used for identifying the high alarm
setpoints and when a high alarm is triggered.
i
OXYGEN HIGH ALARM LIMIT —
High oxygen alarm setpoint. Audible and visual alarms
will trigger when this limit is exceeded. Double dashes (--) indicates the alarm is
inactive.
o
CALIBRATION REMINDER —
The calibration reminder symbol is located at the
bottom of the display. This symbol will be lighted after one week has elapsed from the
previous calibration.
p
SLEEP MODE INDICATOR —
The sleep mode Indicator is used to reduce battery con-
sumption. See section 3.5 Sleep Mode Operation.
a
LOW BATTERY INDICATOR —
The low battery indicator is located at the bottom
of the display and is only activated when the voltage on the batteries are below a nor-
mal operating level and need to be replaced.
s
ALARM SILENCE/SMART ALARM INDICATOR —
When the silent key
is pressed the
indicator will display with cross bars
to alert condition. When Smart Alarm Mode
Button is pressed the indicator will display with T-bars to alert condition.
d
OXYGEN LOW ALARM LIMIT —
Low oxygen alarm setpoint. Audible and visual alarms will
trigger when this limit is exceeded.
f
LOW ALARM INDICATOR —
Low alarm symbol used for identifying the low alarm
setpoints and when a low alarm is triggered.
g
<18% ALARM INDICATOR —
The <18% alarm indicator is located above the Low Alarm
Indicator digits. When the low alarm setting is set below <18%, the indicator will flash
each second to alert the operator of this special condition. See section 3.1.1 for setting
this low alarm condition.
1.4 Max-550E Oxygen Sensor
The Max-550E is a galvanic, partial pressure sensor that is specific to oxygen. It consists of
two electrodes (a cathode and an anode), a FEP membrane and an electrolyte. Oxygen dif-
fuses through the FEP membrane and immediately reacts electrochemically at a gold cathode.
Concurrently, oxidation occurs electrochemically at a lead anode, generating an electrical cur-
rent and providing a voltage output. Electrodes are immersed in a unique gelled weak acid
electrolyte which is responsible for the sensors long life and motion insensitive characteristic.
Since the sensor is specific to oxygen, the current generated is proportional to the amount of
oxygen present in the sample gas. When no oxygen is present, there is no electrochemical
reaction and therefore, negligible current is produced. In this sense, the sensor is self-zeroing.
CAUTION:
The Max-550E oxygen sensor is a sealed device containing a mild acid electro-
lyte, lead (Pb), and lead acetate. Lead and lead acetate are hazardous waste constituents and
should be disposed of properly, or returned to Maxtec for proper disposal or recovery.
CAUTION:
Dropping or severely jarring the sensor after calibration may shift the calibra-
tion point enough to require recalibration.
CAUTION:
The flow diverter for the sensor is for use with flowing gases only.
DO NOT
use the diverter when performing static sampling, such as in incubators, oxygen
tents, oxygen hoods, etc.
2.0 SETUP PROCEDURE
2.1 Battery Installation/Replacement
All MaxO2 ME units are powered by four, AA, alkaline batteries (4 x 1.5 Volts) and are shipped
without the batteries installed. The battery compartment is accessible from the back side of
the unit. Batteries should be changed by qualified service personnel. Use only brand name
batteries. Replace with four AA batteries and insert per orientation marked on the device.
When batteries are installed in the MaxO2 ME, the unit initiates a self diagnostic test. All seg-
ments of the LCD readout are turned on for approximately 2 seconds. The audio buzzer sounds
and the high and low alarm LEDs are illuminated. When the diagnostic test is completed suc-
cessfully, the word "CAL" will display and then automatically initiate a calibration.
WARNING:
Battery replacement by inadequately trained personnel could result in a
safety hazard. The MaxO2 ME will automatically perform a new calibration any time the bat-
teries are removed or replaced. Ensure that the sensor is exposed to either 20.9% oxygen
(room air) or 100% oxygen when changing the batteries to avoid mis-calibration.
To install the batteries:
1. Release the thumb screw by turning it counter-clockwise until it pops out.
2. Install the four, AA, alkaline batteries (4 x 1.5 Volts) in the unit, observing the
orientation shown on the plastic inside the compartment.
3. Slide the battery compartment cover back onto the case. Press in on the thumb screw
while turning it clockwise until it engages the thread in the enclosure. Turn until it is
lightly tightened.
DO NOT
over-tighten.
WARNING:
Electrical shock or damage to the equipment may occur if an inappropriate
external power supply is used. Maxtec recommends using only the Maxtec approved external
power supply as listed in Section 9.0 Spare Parts and Accessories.
To protect the unit from potential leaky battery damage always remove batteries when the
unit is going to be stored (not in use for 30 days or more) and replace dead batteries with
recognized name brand AA Alkaline batteries.
2.2 Calibrating the MaxO2 ME Monitor
2.2.1 Before You Begin
A protective film covering the threaded sensor face must be removed; wait approximately 20
minutes for the sensor to reach equilibrium.
Next, the MaxO2 ME monitor should be calibrated. Thereafter, Maxtec recommends calibra-
tion on a weekly basis. However, more frequent calibration will not adversely affect product
performance.
Calibration of the instrument should be performed when the temperature of the gas stream
changes by more than 3 degrees Celsius.
Changes in barometric pressure can affect the oxygen reading. A 1% change in the barometric
pressure results in an error of 1% of actual reading (Example: If you are reading a 50% oxygen
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