Dokument
Rev
V1.0
Page
1 (4)
User manual
CO2 CALIBRATOR
General
CO2 CALIBRATOR is used to zero calibrate carbon dioxide sensors. The unit produces
carbon dioxide free air from the ambient air.
The main process is that soda lime is used to absorb the carbon dioxide in the air. Carbon
dioxide reacts chemically with the calcium hydroxide and sodium hydroxide in soda lime to
form calcium carbonate and sodium carbonate. The air that has passed through soda lime
contains much less carbon dioxide.
If the soda lime has a violet colour it has lost much of its absorbing capability and can no
longer be used to produce carbon dioxide free air. Several tests show that this colour
indicator cannot be trusted. The colour indication disappears after a short time so the
absorption power of the cartridge can easily be overvalued. If a sensor is zero calibrated with
air containing to much carbon dioxide the readings of the sensor will be too low. Tests have
shown that a cartridge with 5 ml of soda lime has an average absorption time of about 9
hours.
Dokument
Rev
V1.0
Page
2 (4)
Function parameters
Battery charging
The red LED is lit with a fixed light when the battery is charged (no indications of any alarm)
Change CO
2
absorber
The CO
2
absorbent cartridge needs to be replaced when red LED is flashing evenly. (The
CO
2
absorbent cartridge has been used more than 8.5 hours)
Pump on
The green LED is lit with a fixed light when the pump is working (no indications of any alarm)
Prealarm
The unit is operating and after 21 min the green LED starts to flash with long pulses. This
indicates that the unit will shut down automatically within 4 min if operated on battery.
The unit will continue to operate if the charger is used. The green LED will flash with long
pulses but the unit will continue to operate.
Low battery
The unit is operating and the green LED starts to flash with short pulses. This indicates that
the battery voltage is below 7,1V.
Technical data
Weight 258 grams included absorbent cartridge (8 grams)
Length 156mm
Width 89mm
Thickness 26mm
Gas flow out 320-340ml/min
(Gas flow can be changed between 50ml-350ml/min by hard ware)
Volume of CO
2
absorbent cartridge
The volume with maximum filling = 7ml (marked size 5ml length=72.2 mm outer diameter
=13.7 mm)
The absorbent power of the absorbent cartridge is dependent of several factors, but the
minimum operational time is 8.5 hours with soda lime from Scarlau.
(Factors that affect the absorbent power is type of chemicals, packing density of chemicals
the tilt of the unit and the suction/pressure of the pump)
The average flow of the pump through an OBA8 sensor is 320ml/min
Dokument
Rev
V1.0
Page
3 (4)
Verification of absorbent by high CO2 concentration
The CO
2
concentration of incoming air is 3000 ppm.
For best result the Zero Calibration Kit should be in operation a while after changing the CO
2
absorbent cartridge so that the cartridge will stabilise.
Battery performance
Battery type Li Ion 2/2S1-LP103450AR/SR 7,4V 1550mAh. 11,47Wh
Charging time is about 5.2-6 hours.
CO2 concentration after passing through Zero Calibration Unit
0
20
40
60
80
100
120
140
160
180
200
00:00:00 02:24:00 04:48:00
07:12:00 09:36:00 12:00:00 14:24:00 16:48:00
19:12:00
21:36:00
Time hours
ppm CO2
Battery performance
7
7,2
7,4
7,6
7,8
8
8,2
8,4
8,6
00:00:00 01:12:00 02:24:00 03:36:00 04:48:00 06:00:00 07:12:00
Time hours
Battery voltage V
0
0,01
0,02
0,03
0,04
0,05
0,06
0,07
Battery voltage (V)
Charge current (A)
Dokument
Rev
V1.0
Page
4 (4)
The battery is charged during operation
Operation time of the battery
Operation time by normal operation is 15 hours before the low battery alarm is activated. The
battery will shut down automatically when the battery voltage is below 5,0V.
Service life of the battery
The service life of the battery is dependent of its discharging and charging cycles. The
service life of the battery should be 1000 cycles before the capacity is below 85% if the
charging current is 400mA and the discharging current is 80mA.
The battery will last about four years with three cycles of discharges and recharges a week.
(High storage temperatures or frequent cycles of discharges and charges may shorten the
battery life)
If the Zero Calibration Kit is in standby mode the battery should be charged at least once in a
month. Before longer storage the battery should only be charged to about 75 %, four hours
charging time.
0
1
2
3
4
5
6
7
8
9
13:40
14:32
15:25
16:17
17:10
18:02
18:55
19:47
20:39
21:32
22:24
23:17
00:09
01:02
01:54
02:46
03:39
04:31
05:24
06:16
07:09
08:01
08:53
09:46
10:38
11:31
12:23
13:16
14:08
-0,1
-0,05
0
0,05
0,1
0,15
0,2
0,25
0,3
0,35
0,4
Battery vol tage (V)
Charge current (A)
Typical trickle charge
Battery voltage (V)
/
