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8.6
C
ALIBRATION
Instruments and sensors are all factory-calibrated and do not normally require further inter-
ventions of the user. Anyway, a new sensor calibration can be performed for:
o
CO at zero ppm,
o
CO
2
at any reference value within the measurement range,
o
High accuracy R.H. (HD35ED…TC and HD35ED…TV models) at 75% and 33%,
o
Differential pressure at zero.
R.H. calibration is not available for HD35ED…TVI models and for models with internal sensors
(HD35ED[G]14bNAB and HD35ED[G]1NAB).
No calibration is scheduled for temperature sensors.
For a correct calibration of the probes, it is crucial to know and respect the physical phenom-
ena which underlie measurements: for this reason, it is recommended to thoroughly follow the
following instructions and to perform new calibrations only if in possession of adequate techni-
cal knowledge and instruments.
To access calibration, the data logger must have the user-calibration option set:
o
In models with graphic LCD, select the menu item
Calibration
⇒
Calibration Type
and set the
User
option.
o
In models with custom LCD, select the menu item
CAL_MENU
⇒
CAL_TYPE
and set the
User
option.
The calibration procedure deletes the data of the previous user calibration. In case of failed
procedure, you can always return the instrument to factory calibration by selecting:
o
in models with graphic LCD, the menu item
Calibration
⇒
Calibration Type
and setting the
Factory
option;
o
in models with custom LCD, the menu item
CAL_MENU
⇒
CAL_TYPE
and setting the
FACT
(factory) option.
Calibration can be performed with HD35AP-S software (see software instructions) or, if the data
logger has a display, through the front keyboard.
8.6.1
CO
SENSOR
C
ALIBRATION
This calibration is available in HD35ED[G]14bNAB and HD35ED[G]1NAB models.
The
zero
of the CO sensor can be calibrated
in clean air (in outdoor environment CO concen-
tration is less than 0.1ppm) or with the aid of nitrogen bottles (cod. MINICAN.12A).
To use the nitrogen bottle, unbolt the two screws fixing the sensor protection grid, remove the
grid and connect the tube with the rubber sleeve coming from the bottle to the CO sensor
head. Supply the gas by adjusting the bottle flow meter so as to obtain a constant flow ranging
within 0.1 and 0.2 l/min.
Fig. 8.6.1: CO sensor position
CO sensor
