Extech Instruments CO250 User manual

User's Guide
CO
2
Meter
Model CO250
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Introduction
Congratulations on your purchase of this Model CO250 Meter. This meter measures CO2 (Carbon
Dioxide) levels, air temp., dew point, wet bulb temperature and humidity 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.
Meter Description
METER
1. Temperature and Humidity sensor
2. CO2 sensor (rear)
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
Wet Bulb Temperature
SYMBOLS
TWA Time weighted average (8 hours)
STEL Short-term exposure limit (15 minutes weighted average)
HOLD Freezes current reading on display
MIN/MAX Minimum/Maximum readings
Low battery indicator
DP Dew point temperature
AIR Air temperature
WBT Wet bulb temperature
% Unit of relative humidity
C or F Celsius/Fahrenheit
KEYPAD
Turns the meter on and off.
Enters setup mode.
Sets as non-sleep mode with .
Exits setup page/mode.
Enters CO2 calibration with .
Enters RH calibration with
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.
Selects unit or decreases value in setup.
Activates MIN,MAX,STEL,TWA function.
Saves and finishes settings.
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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, and “Lob” will appear on the display, a beeper sounds and readings
are no longer displayed. (Press any key but the
to stop the beeps). Replace the batteries to
resume normal operation.
You, as the end user, are legally bound (
EU Battery ordinance
) to return all used
batteries,
disposal in the household garbage is prohibited!
You can hand over your
used batteries / accumulators at collection points in your community or wherever batteries
/ accumulators are sold!
Disposal:
Follow the valid legal stipulations in respect of the disposal of the device at the
end of its lifecycle
POWER ON/OFF
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.
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 CO
2
sensor to
respond and 30 minutes for RH.
NOTE: Do not hold the meter close to your mouth or any other source of CO
2
.
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.
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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 CO2(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 CO2 readings for the
past 15 minutes (STEL) or 8 hours (TWA). The lower displays are the current measurements
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.
3. The STEL and TWA values will keep updating every 5 minutes.
ALARM
The meter features an audible alarm to give warnings when CO2 concentration exceeds the set
limit. It emits beeps (Abt.80dB) when CO2 level goes over the set value and stops when any key
(except
) is pressed or the readings fall below the set value. It beeps 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, 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.
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SETUP (alarm limit and temperature scale)
In the normal mode press and hold the
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.
0
and “AL” are displayed.
Press the M
N
/AV button to scroll to P1.
1
for setting CO
2
alarm threshold. The current CO
2
set
value will be blinking.
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
N
/AV button to exit and save the setting or the CAL/Esc button to exit
without saving and return to P1.
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
N
/AV button to save the setting or press the CAL/Esc button exit without saving and return
to P3.
0.
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Calibration
CO2 CALIBRATION
The meter is calibrated to a standard 400ppm CO2 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 CO2 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 CO2 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 MN/AV button to enter 75% calibration.
3. “CAL” and calibrating value (75.2% if at 25°C) will blink 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 WindowsTM 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.
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Specifications
Function Range Resolution Accuracy
CO2
0 to 5000ppm 1ppm ±(%5rdg + 50ppm)
5000 to 9999ppm 1ppm Not specified
Pressure dependence: +1.6% reading per kPa deviation from
normal pressure, 100kPa
Temperature -10 to 60°C
14 to 140°F 0.1° ±0.6°C/0.9°F
Humidity 0.0 to 99.9% 0.1% ±3%(10 to 90%)
±5%(< or > 10 to 90%)
Wet Bulb -5 to 60°C
23 to 140°F 0.1° Calculated from RH and
Temperature
Dew Point -20 to 60°C
-4 to 140°F 0.1°
Display Triple LCD with backlight
Sensor Type CO2: NDIR (non-dispersive infrared) technology
Humidity: Capacitance sensor;
Temperature (air): Thermistor
Operating Conditions 0 to 50oC (32 to 122oF); < 95% RH non-condensing
Storage Conditions -20 to 60oC ( -4 to 140oF); <99% RH non-condensing
Power Supply 4 x 1.5V ‘AA’ batteries or AC adaptor (9V/1A)
Battery Life approx. 24 hours (alkaline batteries)
Dimensions / Weight 200x70x57mm (7.9x2.7x2.3”)/190g (6.7 oz.)
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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).
TROUBLESHOOTING
Can’t power on
Press
for more than 0.3 seconds and try again. Check that the batteries have good 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
2
sensor damaged.
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
2
, replace batteries or use an adaptor.
E11: Retry humidity calibration.
E17: Retry CO
2
calibration.
E31: Temperature sensor damaged.
E34: Humidity sensor damaged.
CO
2
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
2
concentration in occupied building should 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
2
at 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.
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All rights reserved including the right of reproduction in whole or in part in any form
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