iWorX GA-200A User manual

GA-200A Carbon Dioxide and Oxygen Gas Analyzer GA-200A-1
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Overview
The GA-200A is an analyzer that integrates a gas
sampling system with sensors to measure and display
the concentrations of oxygen and carbon dioxide in a
sample as the percentage of a gas in the sample by
volume. This method of expressing the concentration of
a gas in a sample is also known as the percent volume
fraction. In addition to the sampling and sensing systems
in the GA-200A, the unit has a fluorescent display used
for programming the unit and observing measurements,
a keypad for programming the unit’s operation and
calibration, and analog outputs that allow the unit to be
connected to data recording units like the iWorx 214.
When measuring the concentrations of oxygen and
carbon dioxide in a gas, a sample is pumped from the
input port on the front panel of the GA-200A, through the
sample cell, and out an exhaust port on the back panel
of the unit. Gas samples are drawn into the unit through
an external filter on the input port that protects the
sensors from contamination and through Nafion tubing
on the filter that removes moisture from the samples that
would affect the measurements and the units calibration.
The oxygen concentration of the gas in the sample cell
is measured using laser diode absorption technology.
The laser diode in the oxygen sensor produces light at a
wavelength (760 nanometers) that is absorbed by
oxygen. The light passes through the gas pumped into
the sample cell and onto the surface of a detector. The
output of the sensor is inversely proportional to the
concentration of oxygen in the sample because the
amount of light reaching the detector decreases as the
concentration of oxygen in the sample increases. The
GA-200A has a very fast response time that enables
breath to breath analysis of gas concentrations because
the unit analyzes the gas sample every 10 milliseconds,
or 100 times per second. During each measurement
interval, the analyzer is zeroed automatically by
electronic tuning of the laser to a wavelength not
absorbed by oxygen.
Figure GA-200A-1: The front panel of the GA-200A gas analyzer with filter.
Front Panel: Keypad and Display
The front panel of the GA-200A has a keypad, a
display used to program the modes and parameters of
the unit, and an inlet port for the gas sample (Figure GA-
200A-1 on page GA-200A-1). The main operational
modes of the unit are selected by pressing one of the
following keys: RUN, TEST, CAL 1, CAL 2, FLOW, or
ALARM. After a key is pressed, the settings for that
function will appear in the display window.
If the SETUP key is pressed, the user enters a
succession of windows that allow the operations and
measurement parameters of the unit to be programmed.
Pressing the UP or DOWN key will change the mode or
value of the parameter. Pressing the ENTER key stores
the setting or selected value, and pressing the RUN key
exits the Setup menu.

GA-200A Carbon Dioxide and Oxygen Gas Analyzer GA-200A-2
Figure GA-200A-2: The rear panel of the GA-200A gas analyzer
Rear Panel of GA-200A
The rear panel of the GA-200A has the following
features: switch; power input; a RS-232 serial port for
connection to a computer, oxygen sensor output, and
gas outlet. The output of the carbon dioxide sensor is
incorporated into the relay terminal which allows the unit
to be connected to other devices (Figure GA-200A-2 on
page GA-200A-2).
1Power for the GA-200 is supplied by an external power
supply. The power supply is connected to the unit through
the connector labeled 12V, 1.5A. Press the side of the
power switch labeled Ito turn on the GA-200A. Press Oon
the switch when it is time to turn the unit off.
2The GA-200A can be interfaced to a computer through a
serial (RS-232) data stream. The default data format is 9600
baud, 8 bit, and no parity with alternate baud rates of
2400, 4800, 19200, and 38400 selected by the interface
commands. The signals present are RXD, TXD, and ground
through the 9-pin D connector on the back panel of the unit.
3The signal from the oxygen sensor can be recorded from
the BNC output labeled OXYGEN SENSOR, 0-1V=0-100%.
The amplitude of the signal ranges from 0 to 1 Volt DC
which corresponds to a range of 0 to 100% oxygen, or 1mV
for each 0.01% oxygen. The ground of this output is
common to the instrument case and the power supply.
4The exhaust port of the sampling circuit is labeled OUTLET.
A scavenging system can be connected to this port to
collect any gases passing through the GA-200A.
5Several relays are available from the terminal block on the
rear panel of the GA-200A: These relays are normally open,
but close when the oxygen sensor detects various alarm
conditions. For DC loads, these relays are rated from 5
Amps at 30 Volts DC to 0.25 Amps at 300 Volts DC in an
open circuit. For AC loads, these relays are rated from 5
Amps at 250 Volts. When the sockets are numbered from
left to right:
•Sockets 1 (Common), 2 (NC), and 3 (NO) are the connec-
tions for Limit Relay A.
•Sockets 4 (Common), 5 (NC), and 6 (NO) are for Limit
Relay B.
•Sockets 7 (Common), 8 (NC), and 9 (NO) are for Warning
Relay.
•Sockets 10 (Common), 11 (NC), and 12 (NO) are for
System OK.
6An analog output for the carbon dioxide sensor and an
additional analog output for the oxygen sensor are available
from the terminal block. These outputs are non-isolated
current sources that are referenced to the current output
ground. The range of each current output is 4 to 20 mA and
a maximum output voltage of 10 Volts. The oxygen and
carbon dioxide concentrations that are equal to the outputs
at 4 mA and 20 mA are normally set to the low and high
limits of the sensitivity ranges of the two gases, respec-
tively: For example, the 4 mA current output of the oxygen
sensor is set to 0%, and the 20 mA current output is set to
100%
•Socket 13 is the Ground for the both current outputs.
•Socket 14 is the oxygen current output.
•Socket 15 is the carbon dioxide current output.
Items Provided with the GA-200A Gas Analyzer
External filter with Luer–Lock fittings
Nafion sampling tube with Luer-Lock fittings
Power supply
Male BNC-BNC cable
Male BNC-Two Wire cable
GA-200A Users Manual
GA-200A Setup
1Position the GA-200A gas analyzer on the desktop, so that
the analyzer can be connected to the data recording unit
and the source of the gas sample at the same time.

GA-200A Carbon Dioxide and Oxygen Gas Analyzer GA-200A-3
2Connect the male BNC-two wire cable included with the
GA-200A between the output of the carbon dioxide sensor,
which is located on the terminal block on the rear panel of
the analyzer, and the BNC input of Channel 1 on the IWX/
214:
•Find the color-coded wires on one of the cable.
•Insert the red wire into Socket 15 on the terminal block, as
counted from left to right. This socket is the current output
signal of the sensor (Figure GA-200A-3 on page GA-200A-3).
•Insert the black wire into Socket 13 on the terminal block, as
counted from left to right. This socket is the is the reference
ground for that signal.
•Connect the other end of the cable to the BNC input of
Channel 1 on the recorder.
3Connect the BNC output of the oxygen sensor, labeled
Oxygen Sensor and 0-1V=0-100%, to BNC input of
Channel 2 on the recorder using a male BNC-BNC cable.
Figure GA-200A-3: The back of the GA-200A gas analyzer showing the
cables attached to the outputs of the carbon dioxide sensor, on the left, and the
oxygen sensor, on the right.
4Place a filter on the inlet port of the GA-200A (Figure GA-
200A-1 on page GA-200A-1). Connect a Nafion sampling
tube to the open end of the filter.
5Insert the coaxial connector on the end of the power supply
cable into the socket on the rear panel of the unit that is
labeled 12V and 1.5A. Connect the power cord to the power
supply. Plug the power cord into the electrical outlet.
6Use the power switch to turn on the GA-200A. As the unit
powers up, the display on the front of the unit will light up.
7When the GA-200A is powered up, the instrument initially
displays the model of the unit, the version of the firmware on
the unit, and the measurement mode. It also indicates that it
is conducting a SEARCH for the calibration relationships
used on the unit.
8When the calibration functions are found, SEARCH
changes to LOCK and the measured concentration of
oxygen in the sample is displayed.
9As the temperature of the sample cell increases to its
nominal temperature, the message on the display indicated
WARMUP.
10 When the GA-200A is ready to be used, the Run Mode
message will appear on the display. The GA-200A will
display a message that looks like either Figure GA-200A-4
on page GA-200A-3, or Figure GA-200A-5 on page GA-
200A-3.
Figure GA-200A-4: One of the possible Run Mode display seen on the front
panel of the GA-200A.
Figure GA-200A-5: Another possible Run Mode display seen on the front
panel of the GA-200A.
Programming the GA-200A Gas Analyzer
The GA-200A is ready to measure the concentra-
tions of gases when it comes from the factory. If the
user needs to change the measurement parameters
of the unit, the directions for changing these param-
eters are included in the next few sections of this
manual.
Oxygen Measurement Mode
The measurement mode of the oxygen sensor can be
viewed by pressing the RUN key. The current
measurement mode of the unit is indicated in the upper
left corner of the display (Figure GA-200A-4 on page
GA-200A-3). On the GA-200A, the operating modes of
the oxygen sensor are designated:
•XC, which is the sensitivity correction mode. This
mode offers the best accuracy for the oxygen sensor in
gas mixtures with components like carbon dioxide and
nitrous oxide, which tend to change the absorption
relationship of the oxygen sensor. This is the best mode
to use when measuring oxygen in the presence of high
concentrations of carbon dioxide, 20%or greater.
•LN, which is the low noise mode. This mode gives
accurate results for the oxygen sensor in gas mixtures
that cause little change to the absorption relationship of
the oxygen sensor. This is the best mode to use the
range of carbon dioxide is normal, 0% to 5%.
Each measurement mode has its own calibration and
pressure compensation factors, which are loaded when
the mode is selected. Each mode must be calibrated
individually prior to its use.
1To select the measurement mode, press the SETUP key on
the front panel of the GA-200A until the display on the unit
reads: Oxygen: Current Concentration (%) on the top
line; and Mode: Current Measurement Mode (XC, LN) on
the second line (Figure GA-200A-6 on page GA-200A-4).

GA-200A Carbon Dioxide and Oxygen Gas Analyzer GA-200A-4
Figure GA-200A-6; The current oxygen concentration detected by the GA-
200A and its measurement mode as seen in Setup mode.
2To change the measurement mode, press the UP or DOWN
key on the front panel of the GA-200A. Press the ENTER
key to store the mode selected.
3Press the RUN key to take measurements.
Setup Mode
The concentrations of the gases used in the calibration
of each sensor, the air flow through the sample cell, and
the set points for the alarms warning of abnormal gas
concentrations or flow rates can all be configured in
setup mode.
1To enter the setup mode, press the SETUP key on the front
panel of the GA-200A. Each press of the SETUP key
advances the programming to the next parameter. Press the
BACK key to return to the preceding parameter.
2To modify the displayed parameter, press the UP or DOWN
key until the desired value for the parameter is displayed.
Press the ENTER key to store the displayed value of the
parameter in the programming.
Time Response Filters
The controls of the time response filters, labeled O2
Filter and CO2Filter, are the first parameters to appear
on the display after the Setup key is pressed. These
functions set the time response of the analyzer during
oxygen and carbon dioxide measurements. The filter
settings, which range from 0 to 13, control how
frequently the measurements are updated (Table GA-
200-1 on page GA-200-4). For example, a setting of 3
provides a running average of the gas measurements
every 80 milliseconds. This is the appropriate filter
setting for measuring oxygen and carbon dioxide
concentrations during breath by breath determinations of
VCO2and VO2. The appropriate filter setting for
measuring oxygen and carbon dioxide concentrations
from a mixing chamber is 7, which is the default setting.
1To change the O2filter setting, press the SETUP key until
O2Filter and its Filter Setting (0-13) and Response Time
appear on the display (Figure GA-200A-7 on page GA-
200A-4). Press the UP or DOWN key to select another
setting for the O2Filter. Press the ENTER key to store the
setting.
2To change the CO2 filter setting, press the SETUP key. CO2
Filter and its Filter Setting (0-13) and Response Time will
appear on the display. Press the UP or DOWN key to select
another setting for the CO2Filter. Press the ENTER key to
store the setting.
Figure GA-200A-7: The setting of the O2 Filter as seen in Setup mode.
3Press the SETUP key to continue programming, or press
the RUN key to take measurements.
Sampling Flow Rate
To measure oxygen and carbon dioxide concentra-
tions, gas samples are taken from the main stream of
gas flowing through spirometry equipment or other
devices using a pump system built into the GA-200A.
The gas sample enters the unit through the inlet port on
its front panel. Place a filter on the inlet port to prevent
contamination of the sensor. Place a Nafion sampling
tube on the filter to humidify dry calibration gases, or
dehumidify saturated gases from breathing circuits, to
the same level as the room.
Calibration gas can be flowed into the unit from a
pressured cylinder when the sample pump is either ON
or OFF at a rate of 50 to 350 milliliters/minute (ml/min).
If the flow rate of the gas sample from a pressurized
cylinder exceeds the flow rate of the sample system, the
sample pump will automatically turn off. This condition
will not damage the analyzer, but it should be corrected
before calibration and measurement are performed.
Ta bl e GA -2 00-1: O2- CO 2Fi lters
Se tt ing R esp ons e
0 No fil ter ing
1 20 m s run nin g ave rag e
2 40 m s run nin g ave rag e
3 80 m s run nin g ave rag e
4 16 0 ms ru nni ng av era ge
5 20 0 ms ex pon ent ia l res pon se
6 30 0 ms ex pon ent ia l res pon se
7 50 0 ms ex pon ent ia l res pon se
8 1 seco nd ex pon ent ial r esp ons e
9 2 seco nds e xpo nen tia l res pon se
10 4 seco nds e xpo nen tia l res pon se
11 8 seco nds e xpo nen tia l res pon se
12 16 s eco nds e xpo nen ti al re spo nse
13 Pr edict ion f ilt er t o enh anc e re spon se

GA-200A Carbon Dioxide and Oxygen Gas Analyzer GA-200A-5
1Use the controls on the regulator of the gas cylinder to
adjust the flow of gas into the GA-200A to a value between
100 and 150 ml/min to conserve gas. If a sensitive external
flow meter is not available, the flow meter in the GA-200A
can be used to adjust the flow rate. Press the FLOW key on
the front panel of the GA-200A to display the flow rate of the
gas entering the unit (Figure GA-200A-8 on page GA-200A-
5) and adjust the rate to the appropriate level using the
regulator on the gas cylinder. The operating capacity (drive)
of the sample pump is also displayed on the screen.
Figure GA-200A-8: The flow rate and pump efficiency as seen in Flow mode.
2The sampling system of the GA-200A can be used to bring
calibration gases and samples into the unit at a rate of 50 to
250 ml/min. At the factory, the flow rate of the sample
system is set to 100 ml/min. To adjust the flow rate of the
sampling system in the GA-200A, press the SETUP key
repeatedly until the Flow Setpoint parameter is displayed
on the screen (Figure GA-200A-9 on page GA-200A-5).
Press the UP or DOWN key to adjust the flow rate. Setting
the flow rate to zero disables pump drive. Press the ENTER
key to store the selected sample flow rate in the
programming of the unit.
Figure GA-200A-9; The flow setpoint as seen in Setup mode.
3Ordinarily the sample pump runs continuously under
feedback control that maintains the flow rate through the
sampling system at the desired setpoint. However, special
applications may require that the pump be turned off for
long periods of time or turned on only for short durations.
Press the SETUP key to the display: Flow: current flow
rate; and Pump State: On, Off, or Max (Figure GA-200A-
10 on page GA-200A-5). Press the UP or DOWN key to
change the pump mode.
Figure GA-200A-10: The flow rate and pump state as seen in Setup mode.
Note: The Pump Mode function in the Setup Menu is used
only for testing the pump. Its value is not saved in the
programming of the unit.
Calibrating the GA-200A
The GA-200A is calibrated at the factory and is ready
to measure and record both oxygen and carbon dioxide
concentrations over the ranges normally recorded from
human and animal subjects.
The gas analyzer will need to be calibrated prior to each use.
When calibrating the analyzer, use the following precautions:
•Select the calibration gases that are suited to the calibration
protocol to be performed and the range of concentrations to be
measured.
•Make sure that the expected calibration values displayed on
the analyzer agree with the actual gas being used. These
values are set using the Setup key.
• If the procedure takes longer than expected between
steps of a calibration procedure, the analyzer may time-
out. Return the analyzer to the proper place by pressing
the appropriate Cal key the proper number of times.
•Check Gas errors indicate that the calibration gas used in
the unit does not match the analyzer’s expectations. Verify
proper flow and gas selection should this appear.
•Keep a filter on the analyzer input at all times to prevent
contamination of the analyzer gas sensor cell.
•If you are unable to calibrate, start over by using the Test key
to Restore Factory Calibration.
Start up the GA-200A for Calibration
1Turn on the unit and let it warm up for 30 minutes before
performing the calibration.
2While the unit is warming up, the sampling pump should be
turned off. To turn off the pump, press the SETUP key until
the following display appears: Flow: current flow rate; and
Pump State: On (Figure GA-200A-10 on page GA-200A-5).
Press the UP or DOWN key to change the pump mode to
Off.
3Press the SETUP key until Oxygen and its concentration
(%) appears on the top line; and, Mode and the current
measurement mode (XC, LN) appears on the second line
(Figure GA-200A-4 on page GA-200A-3). Press the UP or
DOWN key until the LN mode is displayed. Press the
ENTER key to store the measurement mode in the
programming.
4After the 30 minute warm-up period, turn on the sampling
pump of the GA-200A. Press the SETUP key until the
following display appears: Flow: current flow rate; and
Pump State: Off (Figure GA-200A-10 on page GA-200A-5).
Press the UP or DOWN key to change the pump mode to
On

GA-200A Carbon Dioxide and Oxygen Gas Analyzer GA-200A-6
Setup the Expected Values of the Calibration Gas
1To set the known concentration of low O2calibration gas,
press the SETUP key until O2Low Cal appears on the first
line of the display (Figure GA-200A-11 on page GA-200A-
6). Press the UP or DOWN key until the concentration of the
low calibration oxygen appears on the display. Press the
ENTER key to save the displayed value as the low oxygen
calibration concentration.
Figure GA-200A-11: The low oxygen calibration concentration as seen in
Setup mode.
2To set the known concentration of high O2calibration gas,
press the SETUP key until O2High Cal appears on the first
line of the display (Figure GA-200A-12 on page GA-200A-
6). Press the UP or DOWN key until the concentration of the
high calibration oxygen appears on the display. Press the
ENTER key to save the displayed value as the high oxygen
calibration concentration.
Figure GA-200A-12: The high oxygen calibration concentration as seen in
Setup mode.
3To set the known concentration of low CO2calibration gas,
press the SETUP key until CO2Low Cal appears on the
first line of the display (Figure GA-200A-13 on page GA-
200A-6). Press the UP or DOWN key until the concentration
of the low calibration carbon dioxide appears on the display.
Press the ENTER key to save the displayed value as the
low carbon dioxide calibration concentration.
Figure GA-200A-13: The low carbon dioxide calibration concentration as
seen in Setup mode.
4To set the known concentration of high CO2calibration gas,
press the SETUP key until CO2High Cal appears on the
first line of the display (Figure GA-200A-14 on page GA-
200A-6). Press the UP or DOWN key until the concentration
of the high calibration carbon dioxide appears on the
display. Press the ENTER key to save the displayed value
as the high carbon dioxide calibration concentration.
Figure GA-200A-14: The high carbon dioxide calibration concentration as
seen in Setup mode.
Factory Calibration Procedure
This is the calibration procedure that is the same as
the one used at the factory. This procedure allows:
•Room air to be used as the low calibration values for both the
oxygen and carbon dioxide sensors.
•100% oxygen and 10% carbon dioxide to be used as the
high calibration values for both sensors.
Warning: 1. The concentration of oxygen in any
calibration gas (O2, CO2, or a mixture) should be at least
2%. 2. The difference in the concentrations of oxygen in
gases use for calibration must be at least 8% apart. For
example, a high O2calibration gas of 20.93% can be used
with a low O2calibration gas of 12.0%.
A. Low Point Calibration using Cal1 Key and Room
Air (20.9% O2& 0.04% CO2)
1Connect a Nafion sampling tube to the filter on the inlet of
the gas analyzer. The open end of the tube should be away
from the users to prevent the sampling of exhaled air.
2Press the Cal 1 key. This displays the current O2reading
and the O2low cal point (Figure GA-200A-15 on page GA-
200A-6).
Figure GA-200A-15: The current and low calibration concentrations of
oxygen as seen in CAL 1 mode.
3Wait ten seconds for the calibration gas to move into the
analyzer.
4Pressing the Enter key to start the oxygen calibration cycle.
5Wait for the display to indicate calibration cycle complete,
Calibration OK.
6Press the Cal 1 key again to show the current CO2concen-
tration and the CO2low cal point (Figure GA-200A-16 on
page GA-200A-7).
7Press the Enter key to start the CO2calibration cycle.

GA-200A Carbon Dioxide and Oxygen Gas Analyzer GA-200A-7
Figure GA-200A-16: The current and low calibration concentrations of
carbon dioxide as seen in CAL 1 mode.
8Wait for the display to indicate that the calibration cycle is
complete, Calibration OK.
9Press the Run key to restore display to normal.
10 Remove cal gas tubing from analyzer.
Note: This simple Low Point Calibration using room air can be
performed to check the calibration of the unit.
B. High Point Calibration using Cal2 Key and 100%
O2and 10% CO2
1Connect the input port to the oxygen calibration source.
Make sure that the gas is flowing properly.
2Press the Cal 2 key. This displays the current O2reading
and the O2high cal point (Figure GA-200A-17 on page GA-
200A-7).
Figure GA-200A-17: The current and high calibration concentration of
oxygen as seen in CAL 1 mode.
3Wait ten seconds for the calibration gas to move into
the analyzer.
4Pressing the Enter key to start the oxygen calibration
cycle.
5Wait for the display to indicate calibration cycle complete,
Calibration OK.
6Remove the oxygen cal gas from the analyzer input and
turn off the oxygen cal gas valve.
7Connect the input port to the CO2calibration source. Make
sure that the gas is flowing properly.
8Press the Cal 2 key again to show the current CO2concen-
tration and the CO2high cal point (Figure GA-200A-18 on
page GA-200A-7).
9Wait ten seconds for the calibration gas to move into
the analyzer.
10 Press the Enter key to start the CO2calibration cycle.
Figure GA-200A-18: The current and high calibration concentrations of
carbon dioxide as seen in CAL 2 mode.
11 Wait for the display to indicate calibration cycle complete,
Calibration OK.
12 Press the Run key to restore display to normal.
13 Remove the carbon dioxide cal gas from the analyzer input
and turn off the carbon dioxide cal gas valve.
Reduced-Range Calibration Procedure
This is the calibration procedure that sets the sensi-
tivity of the gas analyzer to the normal physiological
range. This procedure allows:
•A standard calibration gas mixture, which is commercially
available, to be used as the low calibration value for the
oxygen sensor and the high calibration value for the carbon
dioxide sensor. The most popular mixture contains 12.0% O2
and 5.00% CO2.
•Room air to be used as the high calibration value for the
oxygen sensor and the low calibration value for the carbon
dioxide sensor. Room air contains 20.9% O2and 0.04% CO2.
Warning: 1. The concentration of oxygen in any
calibration gas (O2, CO2, or a mixture) should be at least
2%. 2. The difference in the concentrations of oxygen in
gases use for calibration must be at least 8% apart. For
example, a high O2calibration gas of 20.93% can be used
with a low O2calibration gas of 12.0%.
A. Low Point Calibration using Cal1 Key and
Recommended Gases (12% O2& 0.04% CO2)
1Connect a Nafion sampling tube to the filter on the inlet of
the gas analyzer. Connect the open end of the tube to the
12% oxygen calibration source. Make sure that the gas is
flowing properly.
2Press the Cal 1 key. This displays the current O2reading
and the O2low cal point (12%)
3Wait ten seconds for the calibration gas to move into the
analyzer.
4Pressing the Enter key to start the oxygen calibration cycle.
5Wait for the display to indicate calibration cycle complete,
Calibration OK.
6Remove the oxygen cal gas from the analyzer input and
turn off the oxygen cal gas valve.

GA-200A Carbon Dioxide and Oxygen Gas Analyzer GA-200A-8
7Prepare to sample room air. The open end of the tube
should be away from the users to prevent the sampling of
exhaled air.
8Press the Cal 1 key again to show the current CO2concen-
tration and the CO2low cal point (0.04%)
9Press the Enter key to start the CO2calibration cycle.
10 Wait for the display to indicate that the calibration cycle is
complete, Calibration OK.
11 Press the Run key to restore display to normal.
12 Remove cal gas tubing from analyzer.
Note: This simple Low Point Calibration using room air can be
performed to check the calibration of the unit.
B. High Point Calibration using Cal2 Key and
20.93% O2and 5% CO2
1Prepare to sample room air. The open end of the tube
should be away from the users to prevent the sampling of
exhaled air.
2Press the Cal 2 key. This displays the current O2reading
and the O2upper cal point (20.93%)
3Wait ten seconds for the calibration gas to move into
the analyzer.
4Pressing the Enter key to start the oxygen calibration
cycle.
5Wait for the display to indicate calibration cycle complete,
Calibration OK.
6Connect the input port to the CO2calibration source. Make
sure that the gas is flowing properly.
7Press the Cal 2 key again to show the current CO2concen-
tration and the CO2 high cal point.
8Wait ten seconds for the calibration gas to move into
the analyzer.
9Press the Enter key to start the CO2calibration cycle.
10 Wait for the display to indicate calibration cycle complete,
Calibration OK.
11 Press the Run key to restore display to normal.
12 Remove the carbon dioxide cal gas from the analyzer input
and turn off the carbon dioxide cal gas valve.
Current Output Setpoints
The current outputs for the oxygen and carbon dioxide
sensors are located in the terminal block on the rear
panel of the GA-200A (Figure GA-200A-2 on page GA-
200A-2). The range of current coming from these outputs
ranges between 4 mA and 20 mA. These outputs can be
calibrated by equating specific concentrations of gases
to the high and low limits of the current output range. For
example, an oxygen concentration of 0% can be equated
to the 4mA current output of the oxygen sensor (Figure
GA-200A-19 on page GA-200A-8).
1Press the SETUP key until O2 4mA Iout and its oxygen
concentration appear on the display (Figure GA-200A-7 on
page GA-200A-4). Press the UP or DOWN key to select
another setting for the 4mA current output (Iout). Press
the ENTER key to store the setting.
2Press the SETUP key until O2 20mA Iout and its oxygen
concentration appear on the display (Figure GA-200A-7 on
page GA-200A-4). Press the UP or DOWN key to select
another setting for the 20mA current output (Iout). Press
the ENTER key to store the setting.
3Press the SETUP key and repeat these procedures for the
4 mA and 20 mA CO2current outputs.
Figure GA-200A-19: The oxygen concentration that is equated to a 4mA
current output of the oxygen sensor as seen in Setup mode.
Alarm Status Mode
1Press the ALARM key to display the current state of the
optional alarm relay outputs: Limit A, Limit B, Warning,
and System OK. Each press of the ALARM key shows the
On/Off status of the next relay. Press the BACK key to
cycle backwards through the list of relays.
2Press the SETUP key while in Alarm Status Mode to set up
the thresholds for gas concentrations, low flow, and
pressures (Figure GA-200A-20 on page GA-200A-8).
Figure GA-200A-20: The window in which an alarm for a low concentration
of oxygen in the sample is programmed in Alarm mode.
•The Limit A Alarm will turn ON when the concentration of
oxygen or carbon dioxide is greater than High Threshold A or
lower than Low Threshold A. Individual threshold detectors
can be disabled by setting the limit value to zero.
•The Limit B Alarm will turn ON when the concentration of
oxygen or carbon dioxide is greater than High Threshold B or
lower than Low Threshold B. Individual threshold detectors
can be disabled by setting the limit value to zero.
•The Warning Alarm will turn ON when warning status is
active for low supply voltage, high or low sample flow, high or
low cell pressure, or an out of range absorption.

GA-200A Carbon Dioxide and Oxygen Gas Analyzer GA-200A-9
•The System OK Alarm is ON when self test is good and
absorption line lock is achieved.
Test Mode
1Press the TEST key to display critical instrument param-
eters, such as: the GA-200A serial number and the version
of firmware on the unit; the sample cell temperature and
pressure; and, the laser temperature setpoint and measured
value.
2Some additional functions available in test mode include:
the restoration of calibration values; the restarting of the
unit; the setting of specific oxygen concentrations to
calibrate the 4-20mA current outputs (Figure GA-200A-21
on page GA-200A-9) and the alarm outputs; and, the
ramping of the oxygen concentrations from 0 to 100% to
check the outputs and calibration of the unit (Figure GA-
200A-22 on page GA-200A-9).
Figure GA-200A-21: The specific oxygen concentration used during the
simulation of an oxygen concentration as seen in Test mode.
Figure GA-200A-22: The oxygen concentration during a point in the ramped
simulation of oxygen concentrations as seen in Test mode.

GA-200A Carbon Dioxide and Oxygen Gas Analyzer GA-200A-10
Troubleshooting
Cleaning and Disinfecting
1The external surfaces of the GA-200A can be cleaned by
wiping them with cloth moistened with a mild detergent
solution.
2The external surfaces of the GA-200A can be disinfected by
wiping them with a cloth moistened with 70% isopropyl
alcohol or a 5% bleach solution. Wipe the disinfecting agent
off the surfaces with another cloth moistened with water.
Allow the surfaces to dry before using the unit.
3The internal sample circuit and the sample pump cannot be
disinfected. An external barrier filter on the inlet port must
be used to prevent contamination of the sample circuit.
4If the GA-200A is used to collect samples of inspired and
expired air during breath to breath spirometry, a new
external barrier filter and a new Nafion sampling tube must
be used for each subject.
5If the GA-200A is used to collect samples of expired air from
mixing chambers or similar devices, change the external
barrier filter according to its daily usage. If the unit is used
repeatedly each day, then a new filter should be used every
day. If the unit is lightly used, then the filter could be
replaced each week. The Nafion sampling tube usually
needs to be changed every six months. If the recordings of
gas concentrations get noisy, change the external barrier
filter and the Nafion sampling tube.
Ta bl e GA-200-2: Troubleshooting Guide
Pro blem Pos sibl e Caus e Sol utio n
In corre ct O2o r CO2v alu es di splay ed Un it ou t of ca libra tio n Pe rfo rm t wo poi nt ca lib ratio n
Un it wi ll no t ca lib rat e O2co nce ntr at ion o f low c ali bra tio n ga s
is too f ar fr om di sp lay ed va lue
Pe rform h igh c ali bra tio n wit h 100 % O2
an d ret ry low ca lib rat ion
Ca libra tio n dri fts fr om or igi nal s ett in g Se ns or no t a t op er ati ng tem per atu re
wh en a two po int c al ibr ati on pe rfo rm ed
Verif y gas t emp era tu re is a t 45oC and
reca lib rat e
Un stab le O2val ue is d isp la yed Sa mpl e li ne fi lte r not i nsta lle d or fi lte r
is the w ron g por e siz e Ch eck t ha t the p rop er filt er is i ns ta lle d
Re pea ted Low O 2Alar m Ala rm se tp oin t i s h igh er tha n c urr ent
me asu rem en t Che ck O2so urc e
Re pea ted H igh O 2Ala rm Al ar m se tpoin t i s l owe r t han curr ent
me asu rem en t Che ck O2so urc e
Re pe ate d Low Flow A lar m Bloc ked o r pin che d inl et li ne Ch ange or repair i nle t sam ple l ine
Lo w flo w whi le pu mp is O n Sa mpl e li ne is cl og ged Ch ange fi lte r
Pu mp do es no t ope rat e Flow r ate i s set t o zer o an d/o r pum p is
Off
Se t des ire d fl ow ra te an d/o r tur n pum p
On
O2me as ure men t dri ft In te rna l s amp le lin e l eak pos sib ly due
to hig h ove rpr ess ure
Ch eck for l eak s by sa mpl in g 99. 99% O 2,
th en oc clu de sam ple lin e. If lea kin g,
read ing w ill dri ft to wa rd ro om ai r re adi ng
of 2 0.9 % Con ta ct te ch su ppo rt
Wate r in sa mpl e lin e Na fion sa mpl e lin e is s atu rat ed,
requires changing Re pla ce sa mpl e lin e
O2me as ure men t dri ft In te rna l sca ven ge ou tle t lin e lea k
Di splay f low a nd oc clu de sc ave nge
ou tl et po rt. F lo w sho uld d rop t o ne ar
ze ro . If no t, ca ll tech s upp ort
O2me as ure men t i s not c lo se t o
kn own gas c onc ent rat ion
Ca lib ra tio n ent er ed wi th in app rop ri ate
ca lib ra tio n gas
Re set O 2Span with 1 00% ca libra tio n
gas, t he re pea t Cal 1 an d Cal 2
Di splay ed O2v alu e i s z ero or doe s
no t app ea r aft er on e min ute w arm -up
La ser d iod e o utp ut is no t loc ked to
ox yge n li ne du e to ov erh ea tin g or th e
ag ing o f th e lase r
Po we r off an d res ta rt an aly zer ( aft er
co oling o ff , if ne ces sar y). I f res tart i s
po ss ibl e, pe rfo rm tw o poi nt ca lib rat ion
to res et la ser c ont rol par ame ter s. If t his
fa il s, co ntact t ech s upp ort
Di splay ed O2v alu e i s z ero or doe s
no t app ea r aft er on e min ute w arm -up
Mo ist ur e has c ond ens ed on w ind ows o f
sa mpl e cel l
Po we r on fo r one h ou r wit h dry g as
flow ing t hro ugh inl et to d ry the ce ll