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5.0 CALIBRATION
5.1 Sensor Calibration
5.1.1 Setup
Before a successful calibration run, the unit must be properly configured using the configure-
CHANNELS-CALIBRATION menu selection by selecting the CONCENTRATION, SPAN,
and ZERO for each channel intended to be calibrated. Once properly configured, RUN
CALIBRATION may be initiated. The sequence that occurs when RUN CALIBRATION is
selected is described in section 5.1.3. Calibration may be aborted at any time by selecting
the SETUP-STOP CALIBRATION menu function.
5.1.2 Source
A variety of sources may be used for sensor calibration including:
• Cylinder gas
• Gas generators
• Permeation devices
Gas generators are available from De Nora Water Technologies. Consult De Nora Water
Technologies or your local representative for information on gas generators.
Low gas concentrations are not available for reactive gases, i.e. Cl
2
and SO
2
, therefore
sensors may be calibrated with air or nitrogen as the solvent.
The duration for which a controlled calibration gas concentration must be delivered to
the sensor is controlled by the electronics but as long as five minutes may be required.
Gas is delivered to the sensor from the source using tubing with the following required
specifications:
• Made from inert materials, Teflon is preferred but polyurethane is acceptable
• ¼ inch outside diameter (O.D.)
• 1/8 to 3/16 inside diameter (I.D.)
For gas delivery to the sensor, the tubing is inserted into a ¼ inch hole in the “calibration
cup” which attaches to the sensor/transmitter assembly. Gas delivery rate should be set in
the range of 0.5 to 1.0 liters/minute. When calibration is done, the calibration cup should be
removed for normal gas-sensing operation.
NOTE: Chlorine sensors with the optional sensor check feature do not require the use of a
calibration cap assembly. Calibration gas should be delivered via the 1/4 inch hole located
on the side of the sensor assembly.
The procedure for ZERO CALIBRATION using zero air is identical to that above. ZERO
CALIBRATION may be conducted using ambient air only when the ambient air is known not
to contain any target gas, otherwise “zero air” must be used.
The following section describes the calibration process in detail.
5.1.3 Calibration
The following calibration procedure enables CALIBRATION to be performed by one person.
While a ZERO calibration may be performed independently of a SPAN calibration, a span
calibration should not be performed without performing a zero calibration first. The temporary
alarm “lockout” is enabled by the ZERO calibration procedure. If zero calibration is not run
first, alarms will be generated during the SPAN calibration.
5.1.3.1 Calibration Sequence Overview
• The following is for information only, for actual procedures, refer to sections
5.1.3.2 and 5.1.3.3.
• CALIBRATION mode operation is controlled at the receiver by the keypad buttons.
The CALIBRATION mode is activated by selecting the SETUP-RUN CALIBRATION
menu parameter at the receiver. CALIBRATION may be aborted at any time by
selecting the SETUP-STOP CALIBRATION menu parameter.
RUN CALIBRATION
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