CGP-31
Handheld Carbon Dioxide Meter

CO2 Measurementin Gas or Liquid Phase Samples

Wide Range（0.1 to 100％）

Power Saving Design
2000 hhours continuousimeasurementwith two AA batteries

CGP-31 Handheld Carbon Dioxide Meter
Measurement principle

Speciﬁcations

A diaphragm-type glass electrode based on theelectrochemical principle is employed for this CO2 gas
sensor. According to this principle, when CO2 gas passes
through the diaphragm and dissolves in the inner solution,
the pH of the solution changes. Because the change of thepH is proportional to the CO2 concentration, the degree ofchange is measured to determine the CO2 concentration. The
following ﬁgure indicates the relationship, which exhibits good
linearity characteristics, between the CO2 concentrationand the electric potential of the glass electrode. If there
is a 10-fold change in the CO2 concentration, there is anapproximately 60 mV change in the electric potential.

AmplifierpH electrode
Innersolution

Reference electrode

Measurement
range

CO225℃
50

Diaphragm-type glass electrode method
Liquid phase : 1.49 to 1490 mg/L
Gas phase : 0.1 to 100%

Temperature 5.0 to 50.0℃

CO2Display
range

Liquid phase : 0.000 to 2.020 mg/L, 0.00 to 20.20 mg/L,
0.0 to 202.0 mg/L, 0 to 2020 mg/L
Gas phase : 0.000 to 0.202%, 0.00 to 2.02%,
0.0 to 20.2%, 0 to 202%
Range selection : Automatic/ ManualTemperature −5.0 to 110.0℃
CO2Repeatability±5% FS or less
(Measurement conducted using standard solutions)Temperature ±0.5℃ or less
Response time

90% response : Approx. 2 min.
(Measurement conducted using standard solutions)

Calibration method

Two-point calibration using a standard CO2solutions or standard gases

External output
ports *・RS-232C (non-isolated) : Personal computer orexternal printer EPS-P30 (optional)
・Analog output (non-insulated) : Three output
ports for concentration, temperature, and range

Waterproof
construction(meter part)

IP 67 (enabled when the sensor is connected andon the external I/O ports are masked)＊The meter part can be submerged at a depth of
1 m for up to 30 min.

100

Electric potential（mV）

Principle of diaphragm-type
glass electrode

Relationship between the CO2 concentrationand the electric potential differenceof the glass electrode

Measurement method

Ambient temperature/
0 to 45 ℃ , no more than 90% (no condensation)
humidity

0Power source−50

Two AA alkaline batteries/ nickel hydrogen batteries
Dedicated AC adapter (6 VA, optional) also available

Power consumption Approximately 0.003 W (when using batteries)
CO2 gasCO2 permeable
diaphragm−100

External dimensions Meter part : Approx. 68 mm (W)×35 mm (H)×173 mm (L)0.1

110100CO2 concentration (%)

WeightMeter part : Approx. 280 g (includes batteries)＊Special cable is required to use the RS-232C interface and the analog output
port simultaneously. Please contact us for details.
If the sample is grounded, make sure to insulate the RS-232C and analog
output port.

Features■Excellent selectivity

Note 1）A DKK-TOA stirrer or commercially available stirrer
would be needed to use standard solutions for calibrations.

The diaphragm-type glass electrode method is employed
to guard against the effects of other mixed gases (exceptacid gases and basic gases). There is also no need fordrying sample because the sensor is relatively unaffectedby humidity.

Note 2）The lower (sensing) part of the sensor probe has been designed
for immersion into a liquid samples. However, the upped part,around where the cable entry is located, is not suitable forimmersion into liquid samples. Therefore the sensor probe should
not be completely immersed into liquid samples.

■Concentration conversion function
You can specify to switch between the gas phase
concentration (%(v/v)) and the liquid phase concentration(mg/L).

■Memory function capable of saving
up to 1,000 data items
Supports auto-save for speciﬁed intervals*＊Short interval memory function: 1 sec. to 99 min. 59 sec.
Long interval memory function: 2 min. to 99 hrs. 59 min.
(When using the long interval memory function, the switch turns off (enters sleepmode) after measuring concentration for 1 minute. It remains off until the next
measurement starts.)■Interface for External Devices(Ability to connect the meter to a personal computer, an external printer,and a recorder.)Standard accessories
CO2 electrode ELX-008（cable length : 1m）（Only included when full set is ordered）
Calibration cell CGC-202L（3 pcs）
Powder of CO2 calibration solution : 143D044
Ion strength adjuster: 143D045

Protection cover（with shoulder belt）
Electrode standElectrode holder
AA alkaline battery（trial use）
（2）
Instruction manual

Optional parts
ProductStirrer
External printer（with connection cable）
Analog output cable（1.5 m）
Data acquisition software
RS-232C connection cable（2 m）
AC adapter

Model / Code No.
ST-7
EPS-P30
118N063
GP-LOG
118N062─We also provide special data acquisition sof tware forloading saved measurement data into a personal computerin text format.

Do not operate producuts before
consulting instruction manual.

International Operations:
DKK-TOA Corporation
29-10, 1-Chome, Takadanobaba, Shinjuku-ku, Tokyo 169-8648 Japan
Tel : +81-3-3202-0225 Fax : +81-3-3202-5685

http://www.dkktoa.net

Information and specifications are for a typical system and are subject to change without notice.
Issued on 10/11/2011