User's Guide 99 Washington Street Melrose, MA 02176 Phone 781-665-1400 Toll Free 1-800-517-8431 Visit us at www.TestEquipmentDepot.
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 1 METER 1. Temperature and Humidity sensor 2. CO2 sensor (rear) 2 3. LCD display 3 4. AC Adaptor connector 5. RS232 port 6. Keypad 7. Battery compartment (rear) 4 5 6 7 LCD DISPLAY 1. 2. 3.
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 and “Lob” will appear on the 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).
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).
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 CO2 ALARM Limit When entering setup mode, P1.0 and “AL” are displayed. Press the MN/AV button to scroll to P1.1 for setting CO2 alarm threshold. The current CO2 set value will be blinking. Press the MODE/▲ button to increase or the DP/WBT/▼ button to decrease the value.
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. 2. 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.
Specifications Function CO2 Temperature Humidity Wet Bulb Dew Point Range Resolution Accuracy 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 0.1° ±0.6°C/0.9°F 14 to 140°F ±3%(10 to 90%) 0.0 to 99.9% 0.1% ±5%(< or > 10 to 90%) -5 to 60°C 0.1° 23 to 140°F Calculated from RH and Temperature -20 to 60°C 0.
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.
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.
