az-instrument 7755 User manual

PORTABLE CO2METER
User Manual
English and Deutsche
Languages

ENGLISH
- 1 -
INTRODUCTION
POWER SUPPLY
Thank you for purchasing this portable CO2meter. The meter measure CO2level, air
temperature, dew point, wet bulb temperature and humidity (DP, WB and RH) and is an ideal
instrument for indoor air quality (IAQ) diagnosis.
Poor indoor air quality is considered unhealthy because it causes tiredness, loss of ability to
concentrate, and even illness (ex. Sick Building Syndrome). IAQ monitoring and survey,
especially on CO2level and air ventilation become widely applied in public areas such as
offices, classroom, factories, hospitals and hotels. It is also suggested in regulations of
industrial hygiene in some countries. (See Appendix)
The portable CO2meter uses NDIR (non-dispersive infrared) technology to ensure the reliability
and long term stability. It’s useful in verifying HVAC system performance and air ventilation
control.
FEATURES:
• Triple displays of CO2level, temperature and humidity
• Stable NDIR sensor for CO2detection.
• Statistics of weighted averages
TWA (8 hours weighted average), STEL (15 minutes weighted average)
• Backlight for working in dark area.
• Audible CO2warning alarm,
• Battery and adaptor power supply.
• Easy manual calibration on CO2and humidity.
• PC connects via RS232 interface.
MATERIAL SUPPLIED
This package contains:
• Meter
• 4pcs AA batteries
• Operation manual
• Hand carrying case
OPTIONAL ACCESSORY:
• 33% calibration salt (VZ0033AZ1)
• 75% calibration salt (VZ0075AZ1)
• Adaptor (9V/100 ~ 240V ac)
• RS232 cable and software
The meter is powered by either 4 AA batteries or a DC adaptor (9V/1A output).
Install the batteries into the battery compartment on the rear and make sure they are in correct
polarity and good contact. When an adaptor is used, it will cut off the power supply from
batteries. The adaptor can’t be used as a battery charger.
Fig.1
When battery voltage gets low, “ ” and “Lob” will appear on the
LCD (Fig.1 ) and the beeper will sound. The CO2sensor can’t
work under low voltage, so it beeps to indicate failed CO2
measurement (press any key, except “ ”, to stop the beeps)
and the readings won’t be displayed. Please replace with new
batteries or connect with an adaptor.

ENGLISH
- 2 -
TWA
STEL
HOLD
MIN/MAX
DP
AIR
WBT
%
°E (C/F)
AVG/ftm/m/s
Time weighted average (8 hours)
Short-term exposure limit (15 minutes weighted average)
Readings are freeze unchanged
Minimum/Maximum reading
Low battery indicator
Dew point temperature
Air temperature
Wet bulb temperature
Unit of relative humidity
Celsius/Fahrenheit
Vain icons in these models
CO2concentration in ppm
Relative humidity in %Air temp, Dew point, Welt
bulb temp in °C or °F
LCD DISPLAY
KEYPAD
OPERATION
• Turns on and off the meter.
• Enters setup mode.
• Sets as non-sleep mode with “ ”.
• Exits setup page/mode.
• Enters CO2calibration with “ ”.
• Enters RH calibration with “ ”.
• Freezes the current readings.
• Cancels data hold function.
• Activates or cancel 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.
• POWER ON/OFF
Press “ ” to turn the meter on and off. When power on, it emits a short beep and performs
30 seconds countdown (Fig. 2) for meter warm up, then enters normal mode with current
CO2, temp., and humidity readings displayed (Fig. 3).
Fig. 2 Fig. 3

ENGLISH
- 3 -
The meter starts measurement when power on and update readings every second. In the
condition of operating environment changed (Ex. From high to low temperature), it takes 30
seconds to respond for CO2 sensor and 30 minutes for RH.
NOTE: Do not hold the meter close to faces in case exhalation affects CO2levels.
• TAKING MEASUREMENT
Press “ ” to switch temperature display. The lower left display will cycle from air
temperature dew point temperature (Fig. 4) and wet bulb temperature (Fig.5).
• AIR, DP, WBT
Press “ ” to freeze the readings, “HOLD” icon is
displayed on the left top of LCD (Fig. 6). All current readings
are kept unchanged, except STEL and TWA. Press “ ”
again to cancel the hold function.
• DATA HOLD
Hold down “ ” for more than 1 second to activate and cancel backlight function.
• BACKLIGHT
Under normal mode, press “ ” to see the minimum, maximum, and weighted average
readings. Each press of “ ”, it displays MIN, MAX, STEL, TWA in sequence and returns to
normal mode.
In MIN and MAX modes, it shows the minimum and maximum readings of CO2on the upper
LCD and of AIR or DP or WB temperature and humidity on the lower LCD (Fig. 8).
NOTE:
1.
2.
3.
If the meter is turned on for shorter than 15 minutes, the STEL value will be the weighted
average of readings taken since power on. Same for TWA values appears before 8 hours.
It takes at least 5 minutes to calculate STEL and TWA. The LCD shows “----” (Fig. 9) during
the first 5 minutes from power on.
While all readings are held unchanged, STEL and TWA will keep updating every 5 minutes.
In STEL and TWA modes, the upper LCD shows the weighted average of CO2readings for the
past 15 minutes (STEL) and 8 hours (TWA). The lower LCD are the current AIR, DP/WB
temperature and humidity (Fig. 8 ).
• MIN, MAX, STEL, TWA
Fig. 4 Fig. 5
Fig. 8
Fig. 9
Fig. 6
Fig. 7

ENGLISH
- 4 -
The meter features audible alarm to give warnings when CO2concentration exceeds the limit.
(See P1.0 in setup for setting the alarm threshold). It emits beeps (Abt. 80dB) when CO2level
goes over the set value and stops when any key (except “ ” ) was pressed or readings
fall below the set value. It beeps again when value goes over the limit. Restart the meter if
beeper can’t be stopped.
The meter turns off automatically after 20 minutes of inactivity. To override the function, hold
down “ ” and “ ” for 2 second to turn on the meter until “n” appears.
NOTE: Auto sleep function will be disabled during calibration mode.
The meter is calibrated at standard 400ppm CO2concentration in factory. It’s suggested to do
manual calibration regularly to maintain good accuracy.
Note:
When the accuracy becomes a concern after a long time usage, return to dealers for standard
calibration.
CAUTION:
Do not calibration the meter in the air with unknown CO2concentration. Otherwise, it will
be calibrated as 400ppm by default and leads to inaccurate measurements.
Hold down “ ” under normal mode for more than 1 second to enter setup mode.
To exit setup, press “ ” in P1.0 or P3.0 and it returns to normal mode.
NOTE: P2.0 is not applicable in this model but for future model with CO and CO2
measurement.
• ALARM
When entering setup mode, P1.0 and “AL” (Fig. 10) are displayed on the LCD. Press “ ”
to enter P1.1 for setting CO2alarm threshold. The current set value will be blinking on the
LCD (Fig. 11).
Press “ ” to increase the value or “ ” to decrease. Each press tunes 100ppm and the
alarm range is from 100 to 9900ppm. When the preferred alarm value is set, press “ ” to
save the setting or “ ” without saving and return to P1.0.
• P1.0 CO2ALARM
Press “ ” or “ ” in P1.0 to access P3.0 for setting up temperature scale (Fig. 12).
Press “ ” enters P3.1 with blinking °C or°F current set (Fig. 13) on the lower left LCD. To
switch °C/°F, press “ ” and “ ”. Then press “ ” to save the setting or “ ” without
saving and return to P3.0.
• P3.0 TEMPERATURE SCALE
AUTO POWER OFF
SETUP
CO2CALIBRATION
Fig. 11Fig. 10
Fig. 13Fig. 12
The manual calibration is suggested to be done in fresh outdoor air that is well ventilated and in
sunny weather.

ENGLISH
- 5 -
The meter is calibrated at standard 400ppm CO2concentration in factory. It’s suggested to do
manual calibration regularly to maintain good accuracy.
Note:
When the accuracy becomes a concern after a long time usage, return to dealers for standard
calibration.
Place the meter in the calibration site. Turn on the meter and hold down “ ” and “ ”
simultaneously to enter CO2 calibration mode (Fig. 14) 400ppm and “CAL” are blinking on the
LCD while performing calibration.
The meter defaults to be calibrated the humidity with 33% and 75% salt solution. The ambient
condition is recommended to be 25°C and stable humidity (better to be close to the calibration
value). To abort calibration, just turn off the meter.
Wait about 5 minutes until the blinking stops and the calibration is completed automatically and
back to normal mode.
To abort the calibration, turn off the meter at any time.
NOTE:
Ensure the batteries are with full voltage during the calibration to prevent from interruption or
failed calibration.
RH CALIBRATION
CAUTION:
Do not calibrate the humidity without the default calibration salt. Otherwise, it will cause
permanent damage. Contact the dealer for calibration salt or services.
Plug the sensor probe into 33% salt bottle. Hold down “ ” and “ ” under normal mode
to enter 33% calibration (Fig. 15). “ ” and calibration value (32.7% if at 25°C) are blinking
on the LCD with current temperature at the left.
Meter is now in calibration, and will finish in about 60 minutes when “CAL” and humidity stop
blinking (Fig. 16).
• 33% calibration
After 33% calibration, plug the sensor probe into 75% salt bottle, then press “ ” to enter
75% calibration (Fig. 17).
• 75% calibration
Fig. 16
Fig. 17
Fig. 14
Fig. 15
The manual calibration is suggested to be done in fresh outdoor air that is well ventilated and in
sunny weather.

ENGLISH
- 6 -
TROUBLE SHOOTING
PC CONNECTION
SPECIFICATION
“CAL” and calibrating value (75.2% if at 25°C) are blinking on the LCD with current
temperature at the left. Meter is now calibrating. Wait about 60 minutes until blinking stops,
then calibration is completed and it returns to normal mode.
NOTE:
Users can also calibrate either point. To calibrate 33% only, press “ ” and exit when 33%
calibration is completed. To calibrate 75% only, press “ ” or “ ” within the 5minutes
while initializing 33% calibration.
Press “ ” for more than 0.3 second and try again. Check whether batteries are in good
contact and correct polarity, or the adaptor is well plugged.
• CANNOT POWER ON
Check whether data hold function was activated. (HOLD icon at the left top)
• FIXED READINGS
Check whether the air flow channels on the rear were blocked.
E01
E02
E03
E04
E07
E11
E17
E31
E34
CO2sensor damaged
The value is under range
The value is over range
The original data error results in this error (DP, WB)
Too low voltage to measure CO2.
Replace batteries or use an adaptor.
Retry humidity calibration
Retry CO2calibration
Temperature sensor damaged
Humidity sensor damaged
• SLOW RESPONSE
• ERROR MESSAGES
CO2
Temperature
Humidity
Dew point
Wet bulb
Resolution
0~9999ppm (2001~9999 out of scale)
-10~60° (14~140°F)
0.1%~99.9%RH
-20.0~59.9°C
-5.0~59.9°C
1ppm, 0.1°C/°F, 0.1%RH
The meter can do PC link for online logging and data analysis via RS232 interface and software.
The protocol is as follow:
MEASURING RANGE
A. 9600bps, 8 data bits, no parity.
B. Format (ASCII)
Cxxxxppm: Txxx.xC(F):Hxx.x%:dxxx.xC(F):wxxx.xC(F) LRC CRLF
Description: $CO2:Air:RH:DPL:WBT LRC CRLF

ENGLISH
- 7 -
CO2LEVELS AND GUIDELINES
CO2
Tair
RH
Relay
LCD size
Operating condition
Storage condition
Power supply
Battery life
Meter size
Weight
Standard package
<30 seconds (90% step change)
<2 minutes (90% step change)
<10 minutes (90% step change)
No
(H) 26 x (W) 44 mm
0~50°C,0~95%RH (avoid condensation)
-20~50°C, 0~95% RH (avoid condensation)
AA x 4 pcs
>24 hours (Alkaline battery)
205 (L) x 70 (W) x 56 (H) mm
200g
Meter, manual, AA batteries, hand carry case
250 ~ 350ppm
600ppm
600~1000ppm
1000ppm
Normal outdoor ambient concentrations
Minimal air quality complaints
Less clearly interpreted
Indicated inadequate ventilation; complaints
such as headaches, fatigue, and eye/throat
irritation will be more widespread. 1000ppm
should be used as an upper limit for indoor
levels.
RESPONSE TIME
CO2
Temperature
Humidity
Warm-up time
±50ppm±5% (0~2000ppm)
±0.6°C / ±0.9°F
±3% RH (at 25°C, 10~90%RH);
±5%RH (at 25°C, others)
30 seconds
ACCURACY
NIOSH recommendations
Type 1
Type 2
Indoor areas such as department stores,
theaters, restaurants, libraries, the acceptable
CO2concentration of 8 hours average is
1000pm.
Indoor areas with special requirements of good
air quality such as schools, hospitals, day care
centers, the suggested CO2 level is 600ppm.
EPA TAIWAN: 600ppm and 1000ppm
• NON-ENFORCED REFERENCE LEVELS

ENGLISH
- 8 -
WARRANTY
The meter is warranted to be free from defects in material and workmanship for a period of one
year from the date of purchase. This warranty covers normal operation and does not cover
misuse, abuse, alteration, neglect, improper maintenance, or damage resulting from leaking
batteries. Proof of purchase is required for warranty repairs. Warranty is void if the meter has
been opened.
RETURN AUTHORIZATION
MEASURING / TESTING INSTRUMETNS
Authorization must be obtained from the supplier before returning items for any reason. When
requiring a RA (Return Authorization), please include data regarding the effective reason, the
meters are to be returned along with good packing to prevent any damage in delivery and
insured against possible damage or loss.
Hygrometer / Psychrometer
Thermometer
Anemometer
Sound level meter
Air Flow Meter
Infrared Thermometer
K type Thermometer
K.J.T type Thermometer
K.J.T.R.S.E type thermometer
pH Meter
Conductivity meter
T.D.S Meter
D.O. Meter
Saccharimeter
Manometer
Tacho Meter
Lux/ Light Meter
Moisture Meter
Data Logger
Temperature/ RH transmitter
Wireless Transmitter
ASHREA Standard 62~1989: 1000ppm
CO2 concentration in occupied building should not exceed 1000ppm.
Building bulletin 101 (BB101): 1500ppm
UK standards for schools say that CO2 at averaged over the whole day (i.e. 9am to 3:30pm)
should not exceed 1500ppm.
OSHA: 5000ppm
Time weighted average over five 8-hour work days should not exceed 5000ppm.
Germany, Japan, Australia, UK… : 5000ppm
8 hours weighted average in occupational exposure limit is 5000ppm.
• REGULATORY EXPOSURE LIMIT