MaxTech MAXO2 - Manual (Page 5)

1.4 MAX-250+ Oxygen Sensor
The MAX-250+ oxygen sensor offers stability and extra life.
The MAX-250+ is a galvanic, partial pressure sensor that is specific to oxygen. It
consists of two electrodes (a cathode and an anode), a teflon membrane and an
electrolyte. Oxygen diffuses through the teflon membrane and immediately reacts
at a gold cathode. Concurrently, oxidation occurs electrochemically at the lead
anode, generating an electrical current 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 electrochemi-
cal reaction and therefore, negligible current is produced. In this sense, the sen-
sor is self-zeroing.
CAUTION: The Maxtec ® MAX-250+ oxygen sensor is a sealed device containing a mild acid
electrolyte, 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: Do not use ethylene oxide sterilization. Do not immerse the sensor in any
cleaning solution, autoclave or expose the sensor to high temperatures.
CAUTION: Dropping sensor can adversely affect its performance.
2.0 OPERATING INSTRUCTIONS
2.1 Getting Started
2.1.1 Protect Tape
Prior to turning on the unit, a protective film covering the threaded sensor
face must be removed. After removing the film, wait approximately 20
minutes for the sensor to reach equilibrium.
2.1.2 Remove the Battery Ribbon
A ribbon has been inserted between the two case halves to prevent a battery
connection. Remove the ribbon by pulling it completely out of the case. To
energize the unit tighten all three screws with the included Phillips screwdriver.
NOTE: If you do not tighten all three screws, the unit may not turn on or it may erratically turn
on and off.
3 W W W . M A X T E C I N C . C O M 2 M A N U F A C T U R E D B Y M A X T E C , I N C .
1.2 Component Identification
1.3 Component Description
1. 3 1/2-Digit Display - The 3 1/2 digit liquid crystal display (LCD) provides
direct readout of oxygen concentrations in the range of 0 – 105.0%
(100.1% to 105.0% used for calibration determination purposes). The
digits also display error codes and calibration codes as necessary.
2. Low Battery Indicator - The low battery indicator is located at the top of the
display and is only activated when the voltage on the batteries is below a
normal operating level.
3. “%” symbol - The “%” sign is located to the right of the concentration
number and is present during normal operation.
4. Calibration symbol - The calibration symbol is located at the bottom of the
display and is timed to activate when a calibration is necessary.
5. ON/OFF Key - This key is used to turn the device on or off.
6. Calibration Key - This key is used to calibrate the device. Holding the key
for more than three seconds will force the device to enter a calibration mode.
CAUTION: The device will assume a percent oxygen concentration when calibrating. Be
sure to apply 100% oxygen, or ambient air concentration to the device during calibration
or the device will not calibrate correctly.
Sample Inlet Connection
This is the port at which the device is connected to determine oxygen concentration.
FIGURE 1
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