14 3600 Analyzer for O
2
Measurement—Operator’s Manual
3600O2.OM.E9903
instrument simply needs to be reset to its default “Expected Current” after
repeated re-calibrations.
To reset the instrument, enter the “Modify Options/Membrane”, highlight the
membrane model number you are using, and press “ENTER” to “re-select” the
membrane (see also section 1.4.11).
This informs the instrument that it should perform its calibration against expected
current, rather than against the “Last Calibration”. If the sensor is performing
properly, the instrument will accept a new calibration, and you should now receive
a “Calibration Complete” message.
1.3.3.3 Oxygen Sensor Direct Calibration
A “Direct” calibration routine is used when calibrating the oxygen sensor against a
sample of a known oxygen content (that is, a span gas).
(Note that a instrument normally making dissolved oxygen measurements but
calibrated against a gaseous sample using the procedures below will first have to
be configured as a “partial pressure” analyzer, using the “Modify Options” menus
described in section 1.4.1.)
To calibrate, first select the “Calibrate” from the main menu. Press “ñ” or “ò”
until “Direct” is blinking, then press “ENTER”, to bring up this screen:
CALIBRATION 0000
CONDITION ^
Assuming you know the oxygen content to be a certain value, say 8.123 parts per
million of oxygen, you can adjust the value for these four digits with the“ñ” or
“ò” key, and press “ENTER” to activate. This calibration condition screen
(abbreviated “CC”) appears:
CC = 8.123 ppm 3
UP/DOWN MODIFIES
As with instrument menus for alarms and outputs, the unit of measurement and
range are displayed on the top line along with the known value. Pressing
“ENTER” will record this calibration value; the next screen will relate this
calibration to the previous one, as seen before in the “Calibration in Air” menu. As
before, if the value is not within 50 to 150% of the previous calibration, a
“CALIBRATION OUT OF BOUNDS” message prompts you to take corrective
action.
1.3.3.4 Model 28117 External Pressure Sensor Calibration
The 3600 instrument can be fitted with an external pressure sensor, model 28117,
capable of measuring up to 3.5 bar (50 psia). This pressure sensor is mated to the
model 32002 multi parameter flow chamber, as described in the Installation
Guidelines, and interfaces with the instrument via a 4-pin LEMO connector.
If you wish to calibrate your 28117 pressure sensor against a known pressure,
choose “Extern. Pressure” from “Calibration” menu, and press “ENTER” for the
pressure sensor screen.
PRESSURE SENSOR
50 psia
Press “ENTER”, and the instrument now displays what it believes to be the
current external pressure. You can use this as a monitoring screen later:
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