6
User Manual EE872 Modular Probe for CO
2
, RH, T and p
3 Product Description
3.1 Operation Principle
The EE872 is available in three versions (see also Fig. 5)
EE872-M10...: The probe measures the CO
2
concentration. The sensing module is heated by factory
default setting to prevent condensation. The CO
2
measurement value is available on the
analogue output or on the digital interface.
EE872-M15...: The probe measures the CO
2
and p. Per factory default, the sensing module is heated to
prevent condensation. The CO
2
concentration and p values are available on the digital
interface.
EE872-M13...: The probe measures CO
2
, RH, T and p, and calculates Td. Since per factory default the
sensing module is not heated, the accurate measurement of RH and T is possible. In
case the user activates the probe heating is activated, the RH and T data is not available.
The calculated Td value is still available. All values are available on the digital interface.
All versions provide CO
2
measurement T and p compensated.
The CO
2
measurement is based on the dual wavelength/dual detector NDIR principle. Infrared light is
led through the gas to be examined. One detector is tuned to 4.2 µm, which is the wavelenght absorbed
by CO
2
. The second detector is tuned to 3.9 µm, a wavelenght that is not affected by any gas. The
CO
2
concentration is calculated trom the different outputs of the two according detectors. For more
information, please see
E+E‘s paper on the principles of CO
.
Please note:
Changing the factory setup with respect to heating (on/off) may lead to an additional
measurement error of max. +/- 50 ppm CO
2
. This might lead to a CO
2
measurement accuracy out of
specification.
3.2 Dimensions in mm (inch)
135 mm
(5.3")
M12x1 male connector
64 mm
(2.1")
Ø
25 mm
(0.98
")
61 mm
(2.4")
Fig. 1 Dimensions of EE872
