User's Guide
99 Washington Street
Melrose, MA 02176
Phone 781-665-1400
Toll Free 1-800-517-8431
CO2 Meter
Model CO250
Visit us at www.TestEquipmentDepot.com
Introduction
Congratulations on your purchase of this Model CO250 Meter. This meter measures
2 (Carbon Dioxide) levels, air temp., dew point, wet bulb temperature and humidity
CO
and is an ideal instrument for indoor air quality (IAQ) diagnosis. This meter is shipped
fully tested and calibrated and, with proper use, will provide years of reliable service.
Warranty
EXTECH INSTRUMENTS CORPORATION (A FLIR COMPANY) warrants this instrument to
be free of defects in parts and workmanship for one year from date of shipment (a six
month limited warranty applies to sensors and cables). If it should become necessary to
return the instrument for service during or beyond the warranty period, contact the
Customer Service Department at (781) 890-7440 ext. 210 for authorization or visit our
website www.extech.com for contact information. A Return Authorization (RA) number
must be issued before any product is returned to Extech. The sender is responsible for
shipping charges, freight, insurance and proper packaging to prevent damage in transit.
This warranty does not apply to defects resulting from action of the user such as misuse,
improper wiring, operation outside of specification, improper maintenance or repair, or
unauthorized modification. Extech specifically disclaims any implied warranties or
merchantability or fitness for a specific purpose and will not be liable for any direct, indirect,
incidental or consequential damages. Extech's total liability is limited to repair or
replacement of the product. The warranty set forth above is inclusive and no other
warranty, whether written or oral, is expressed or implied.
Technical support: Extension 200; E-mail: support@extech.com
Repair & Returns: Extension 210; E-mail: repair@extech.com
Product specifications subject to change without notice
For the latest version of this User’s Guide, Software updates, and other up-to-the-
minute product information, visit our website: www.extech.com
Support line (781) 890-7440
2
CO250 V1.2 1/09
Meter Description
METER
1. Temperature and Humidity sensor
CO2 sensor (rear)
2.
3. LCD display
4. AC Adaptor connector
5. RS232 port
6. Keypad
7. Battery compartment (rear)
LCD DISPLAY
1. CO2 concentration in ppm
2. Relative Humidity in %
3. Air Temperature, Dew Point or
SYMBOLS
KEYPAD
Wet Bulb Temperature
TWA Time weighted average( 8 hours)
STEL Short-term exposure limit (15 minutes weighted average)
HOLD Freezes current reading on display
MIN/MAX Minimum/Maximun readings
Low battery indicator
DP Dew point temperature
AIR Air temperature
WBT Wet bulb temperature
% Unit of relative humidity
C or F Celsius/Fahrenheit
Turns the meter on and off.
SET
Enters setup mode.
Sets as non-sleep mode with .
Exits setup page/mode.
CAL
Esc
Enters CO
Enters RH calibration with
2 calibration with .
DP/WBT
Freezes the current reading on display.
Cancels data hold function.
Activates or cancels the backlight.
Selects unit or increases value in setup.
Selects AIR, DP, WBT temps display.
DP/WBT
Selects unit or decreases value in setup.
Activates MIN,MAX,STEL,TWA function.
N
X
M/AV
Saves and finishes settings.
TWA
HOLD
ftm
m/s
STEL
O
CO
1
2
3
4
5
6
7
2
1
%
2
3
3
CO250 V1.2 1/09
Operation
BATTERY INSTALLATION
The meter is powered by 4 AA batteries or a DC adaptor. Install the batteries into the rear
battery compartment observing correct polarity. When an adaptor is used, the batteries will
be disconnected from the meter. The adaptor cannot be used as a battery charger. When
the battery voltage drops below the required level,
display, a beeper sounds and readings are no longer displayed. (Press any key but the
SET
to stop the beeps). Replace the batteries to resume normal operation.
CO
2
O
POWER ON/OFF
SET
Press
to turn the meter on and off. At power up, the meter emits a short beep and
performs a 30 second countdown for meter warm up. It then enters the normal operation
mode with current CO
2, temperature and humidity readings displayed.
CO
2
%
O
TAKING MEASUREMENT
The meter starts measurements when powered on and updates readings every second. If
the operating environment changes (ex. from high to low temp.), it takes 30 seconds for
2 sensor to respond and 30 minutes for RH.
CO
NOTE: Do not hold the meter close to your mouth or any other source of CO
AIR, DP and WBT Measurements
Press the DP/WBT button to switch temperatures display. The lower left display will cycle
from “AIR” air temperature, “DP” dew point temperature and “WBT” wet bulb temperature.
DATA HOLD
Press the HOLD button to freeze the readings, The "HOLD” icon is displayed on the left
top of the display. All current readings are held unchanged, except STEL and TWA. Press
“HOLD” again to cancel the hold function.
BACKLIGHT
Press the MODE/▲
button for more than 1 second to activate or to cancel backlight
function.
and “Lob” will appear on the
%
2.
4
CO250 V1.2 1/09
MIN,MAX,STEL,TWA
In the normal mode, press the Max/AV button to see the minimum, maximum, and
weighted average readings. With each press of the Max/AV button, the meter displays
MIN, MAX, STEL, TWA in sequence and then returns to the normal mode.
In MIN and MAX modes, the meter shows the minimum and maximum readings of CO
(main display), AIR, DP or WB temperatures (lower left display) and Humidity (lower right
display).
In STEL and TWA modes, the main display shows the weighted average of CO
2 readings
for the past 15 minutes (STEL) or 8 hours(TWA). The lower displays are the current
measurements
STEL
CO
2
%
O
NOTE:
1. If the meter has been powered on for less than 15 minutes, the STEL value will be
the weighted average of readings taken since power on. As well, the TWA mode
will display a weighted average of readings prior to 8 hours of operation.
2. The CO250 takes at least 5 minutes to calculate STEL and TWA. The display
shows “----” during the first 5 minutes from power on.
STEL
CO
2
%
O
3. The STEL and TWA values will keep updating every 5 minutes.
ALARM
The meter features an audible alarm to give warnings when CO
the set limit.. It emits beeps (Abt.80dB) when CO
when any key (except
SET
) is pressed or the readings fall below the set value. It beeps
2 level goes over the set value and stops
2 concentration exceeds
again if the value exceeds the limit. Restart the meter if the beeper will not stop.
AUTO POWER OFF
The meter turns off automatically after 20 minutes of inactivity. To override the function,
SET
press and hold down the
and HOLD buttons until “n” appears in the display (approx.
2 seconds) while turning on the meter on. NOTE: Auto sleep function will be disabled
during calibration mode.
2
5
CO250 V1.2 1/09
SETUP (alarm limit and temperature scale)
In the normal mode press and hold the
SET
button for more than 1 sec to enter the setup
mode.
To exit the setup mode, press the CAL/Esc button when either P1.
0 or P3.0 is displayed.
P1.0 CO
2 ALARM Limit
When entering setup mode, P1.
Press the M
2 set value will be blinking.
CO
N/AV button to scroll to P1.1 for setting CO2 alarm threshold. The current
0 and “AL” are displayed.
Press the MODE/▲ button to increase or the DP/WBT/▼ button to decrease the value.
Each press adjusts 100 ppm. The alarm range is from 100 to 9900ppm. When the
preferred alarm value is set, press the M
CAL/Esc button to exit without saving and return to P1.
N/AV button to exit and save the setting or the
0.
P3.0 TEMPERATURE SCALE
Press the MODE/▲ button or the DP/WBT/▼ button in P1.
0 to access P3.0 for setting
the temperature scale.
Press the M
N/AV button to go into P3.1 for setting the temperature units. The currently
selected units (°C or °F) will be blinking in the display. To switch units, press the
MODE/▲ button. Press the M
button exit without saving and return to P3.
N/AV button to save the setting or press the CAL/Esc
0.
6
CO250 V1.2 1/09
Calibration
CO2 CALIBRATION
The meter is calibrated to a standard 400ppm CO
2 concentration at the factory
NOTE: When the accuracy becomes a concern or after a year of use, return to Extech for
a standard calibration.
CAUTION: Do not calibrate the meter in an atmosphere of unknown CO
2 concentration.
1. Place the meter in the 400ppm calibration chamber. Turn the
meter on and hold down the CAL/Esc and MODE/▲ buttons
simultaneously to enter CO
2 calibration mode. 400ppm and
“CAL” will blink on the LCD while performing calibration.
2. Wait about 5 minutes until the blinking stops. The calibration
is then completed and the meter automatically returns to the
normal mode.
NOTE: Ensure the batteries are fresh prior to calibration to prevent an interruption or failed
calibration.
RH CALIBRATION
The meter is calibrated to a standard 33% and 75% salt solution bottle.
CAUTION: Do not calibrate the humidity without the default calibration salt. Otherwise,
permanent damage could occur. Contact the Extech for calibration salts or services.
33% calibration
1. Plug the sensor probe into 33% salt bottle.
2. In the normal mode, Press and Hold the CAL/Esc and
DP/WBT/▼ buttons to enter the 33% calibration. “CAL” and
calibrating value (32.7% if at 25°C) will blink on the LCD with
current temperature at the left.
3. The meter is now calibrating, and will finish in about 60 minutes
when “CAL” and humidity stop blinking.
75% calibration
1. After the 33% calibration, plug the sensor probe into a 75%
salt bottle.
2. Press the M
N/AV button to enter 75% calibration.
3. “CAL” and calibrating value (75.2% if at 25°C) will blinking on
the LCD with current temperature at the left.
4. The meter is now calibrating. Wait about 60 minutes until the blinking stops, then
calibration is completed and the meter will return to normal mode.
NOTE: Single point calibrations are allowed. To calibrate 33% only, press CAL/Esc and
exit when 33% calibration is completed. To calibrate 75% only, press MODE/▲
within the 5 minutes while initializing 33% calibration.
PC CONNECTION
The meter is equipped with an RS-232 PC interface jack (3.5mm phono) for connection to
a PC. The supplied cable and Windows
TM
compatible software allows the user to store
readings in a text file and display real-time measurements in a series of selectable formats.
For more information or specific operating instructions, refer to the User Guide included
with the software.
7
CO250 V1.2 1/09
Specifications
Function Range Resolution Accuracy
CO2
Temperature
Humidity 0.0 to 99.9% 0.1%
Wet Bulb
Dew Point
Display Triple LCD with backlight
Sensor Type CO
Operating Conditions 32 to 122
Storage Conditions -4 to 140
Power Supply 4 x 1.5V ‘AA’ batteries or AC adaptor (9V/1A)
Battery Life approx. 24 hours (alkaline batteries)
Dimensions / Weight 7.9x2.7x2.3” (200x70x57mm)/6.7 oz. (190g)
0 to 5000ppm 1ppm ±50ppm±5%rdg
5000 to 9999ppm 1ppm Not specified
Pressure dependence: +1.6% reading per kPa deviation from
normal pressure, 100kPa
-10 to 60°C
14 to 140°F
0.1° ±0.6°C/0.9°F
±3%(10 to 90%)
±5%(< or > 10 to 90%)
-5 to 60°C
23 to 140°F
-20 to 60°C
-4 to 140°F
2: NDIR (non-dispersive infrared) technology
0.1°
0.1°
Calculated from RH and
Temperature
Humidity: Capacitance sensor;
Temperature (air): Thermistor
o
F (0 to 50oC); < 95% RH non-condensing
o
F (-20 to 60oC); <99% RH non-condensing
8
CO250 V1.2 1/09
Maintenance
CLEANING AND STORAGE
1. The meter should be cleaned with a damp cloth and mild detergent when necessary.
Do not use solvents or abrasives.
2. Store the meter in an area with moderate temperature and humidity (refer to the
operating and storage range in the specifications chart earlier in this manual).
CALIBRATION AND REPAIR SERVICES
Extech offers repair and calibration services for the products we sell. Call the Customer
Service Department for information on calibration services available for this product.
Extech recommends that annual calibrations be performed to verify meter performance
and accuracy.
TROUBLESHOOTING
Can’t power on
Press
contact and the correct polarity or that the AC adaptor is properly connected.
Slow response
Check whether the air flow channels on the rear of the meter are blocked.
Error messages
E01: CO
E02: The value is under range.
E03: The value is over range.
E04: The original data error results in this error (DP, WB)
E07: Too low voltage to measure CO
E11: Retry humidity calibration.
E17: Retry CO
E31: Temperature sensor damaged.
E34: Humidity sensor damaged.
SET
for more than 0.3 seconds and try again. Check that the batteries have good
2 sensor damaged.
2, replace batteries or use an adaptor.
2 calibration.
9
CO250 V1.2 1/09
CO2 Levels and Guidelines
Non-Enforced Reference levels:
• 250 - 350 ppm – background (normal) outdoor air level
• 350- 1,000 ppm - typical level found in occupied spaces with good air exchange.
• 1,000 – 2,000 ppm - level associated with complaints of drowsiness and poor air.
• 2,000 – 5,000 ppm – level associated with headaches, sleepiness, and stagnant,
stale, stuffy air. Poor concentration, loss of attention, increased heart rate and
slight nausea may also be present.
• >5,000 ppm – Exposure may lead to serious oxygen deprivation resulting in
permanent brain damage, coma and even death.
Regulatory exposure limits:
ASHRAE Standard 62-1989: 1000ppm: CO
not exceed 1000ppm.
OSHA: 5000ppm: Time weighted average over five 8-hour work days should not
exceed 5000ppm
Building bulletin 101 (Bb101): 1500ppm. UK standards for schools say that CO
averaged over the whole day(i.e. 9am to 3.30 pm) should not exceed 1500ppm.
Germany, Japan, Australia, UK...: 5000ppm, 8 hours weighted average in
occupational exposure limit is 5000ppm.
Copyright © 2009 Extech Instruments Corporation (a FLIR company)
All rights reserved including the right of reproduction in whole or in part in any form.
2 concentration in occupied building should
2 at
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10
CO250 V1.2 1/09
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