Cambridge Sensotec Rapidox 1100ZR-H-PFC-E O
2
Analyser Instruction Manual
Version 1.2
8
Last printed 22/07/2015 18:08:00
taken to balance the inlet pressure from the calibration gas cylinder with
the back pressure generated by the ejector. When calibrating always make
sure the ejector is running and set at 2bar compressed air. Next attach your
calibration gas cylinder and adjust the regulator so that the pressure reading
on the Rapidox display is between 0 and 25 mbar. This will give you the
correct gas flow and pressure required for a successful calibration. The
pressure display needs to be enabled by following the instructions in
section 7.11. Alternatively a by-pass arrangement can be used – please see
section Error! Reference source not found. for a diagram.
3)
The sensor needs to be exposed to the first calibration gas from a cylinder
(or exposed to ambient air, 20.95% if this is the calibration gas of choice).
Allow several minutes to pass to flush the sensor properly. Wait for the top
line of the display (1) to become stable. To complete the calibration press
and hold the ENT button for two seconds. During this time you will see a
bar graph progress across the lower display. The analyser will then
recalibrate and display “O
2
recalibrated” and then return to normal run
mode. The display will now correctly read the value of the first calibration
gas. Note that if the ENT button is released before two seconds have
elapsed, the recalibration will be aborted and when the analyser eventually
returns to run mode it will use the existing calibration.
4)
Note that the analyser should ideally be calibrated at normal ambient
pressure. If the pressure correction mode is set to AUTO then it is still
possible to perform an accurate calibration at pressures other than ambient.
However above 25mbar (gauge) or below -25mbar (gauge) the display will
flash and “P?” will display to warn you that the pressure is either above or
below the range recommended for accurate calibration.
5)
The analyser predicts the correct signal from the sensor during calibration
and if this is outside the range of expected values then the display will flash
and display “G?” to warn you that either the cal gas flowing over the sensor
is different to the value you have programmed OR the sensor may be old
and approaching the end of its life. Check before proceeding!
6)
To calibrate against the second or third calibration gas, repeat the
procedure from 2 but this time press ENT followed by the UP or DOWN
button to scroll through to the “O
2
Middle” or “O
2
Low” screen. Flush the
sensor chamber with the second calibration gas allowing several minutes
for the new gas to flush through. Wait for the display to become stable
before pressing the ENT button for two seconds. The analyser will then
recalibrate and display “O
2
recalibrated” and then return to normal run
mode. The display will now correctly read the value of the calibration gas.
7)
The analyser is now correctly calibrated and will read accurately between
these two calibration points. Note that this procedure can be performed
remotely using the software described in section 8. You can now repeat
this process for the third calibration gas if required.