KCO-NO2 User’s Manual
90-0201-01
Kele • 3300 Brother Blvd. • Memphis, TN 38133
Page: 11
WWW.KELE.COM
Figure 9:
Location of Calibration Controls. CO is
green; NO2 is yellow.
5 Sensor Calibration
The KCO-NO2 must be calibrated at least every six
months to maintain the specified accuracy.
Calibration entails individually exposing each of the
sensors to two gases of precisely known
concentrations (See
) so the measurement
system can compensate for changes in the sensor’s
sensitivity.
The
UCK-3 kit
is available at Kele.com.
Both sensors first use the same zero gas cylinder for
zero calibration, but then each sensor uses a different
span gas cylinder for the span calibration.
A ‘calibration cap’ is required to cover the sensor body and form an isolated pocket at the sensor
that is filled with the appropriate calibration gas supplied from cylinders of compressed gas through
a regulator connected to it by typically ¼” OD gas tubing. Refer to the documentation for the
calibration kit being used for instructions on how to assemble and operate its gas supply
components.
Each sensor must be sequentially calibrated with two different gases. The Zero gas is the same for
both sensors and is used for the ‘zero’ calibration, which must be done first. The ‘span’ gas is
different for each sensor and used for the ‘span’ calibration which MUST be done ONLY AFTER a
successful zero calibration. Each calibration is started with one of the two calibration buttons
(ZERO and SPAN) for each sensor module as shown in
During calibration and for a period thereafter, the analog outputs are forced to 4 mA and the alarm
relays are both deactivated to avoid spurious alarm conditions from residual span calibration gas
that has not yet dissipated from the sensor.
5.1 Calibration Gases
The table below shows the calibration gases required to calibrate the KCO-NO2.
Sensor
Calibration
Gas
Mixture (by volume)
Kele Order
Nomenclature
BOTH
Zero Gas
Air (18% to 21% O
2
, balance N
2
)
Often called “zero air” or “clean
air”
GAS-02-18
CO
Span Gas
25 ppm CO, balance air
GAS-CO-25
NO
2
Span Gas
10.0 ppm NO
2
, balance air
GAS-NO2-10
TABLE 6
: Gases required to calibrate KCO-NO2