Reference Manual
Calibration procedure
MAN-0076, Revision 09
June 2016
Calibration procedure
25
Section 5:
Calibration procedure
5.1
Full calibration procedure
Prior to attempting calibration read and understand the calibration procedure below. Also see
Figure
5-1
for additional reference.
The following calibration procedure should be followed to ensure an accurate correlation between the
output signal and the gas concentration. For accurate performance, the Millennium II is calibrated
using 50% span gas. The transmitter will however, allow some flexibility in the use of calibration gas
with some sensors; calibration gas outside of 50 % span (10% - 60% span gas) will be allowed on specific
sensor models (see specific sensor manual for details). The calibration gas value can be chosen by
selecting it under “cal. gas value” in the main menu. A full calibration will take approximately 5 minutes
to complete.
Air movement, drafts and wind can cause dilution of calibration gas flow which can cause an erroneous
calibration and inaccurate performance. To avoid this, use a Calibration Cup attached to the bottom of
the sensor. The cup doesn’t have to be removed for normal operation. When the cup is in place, inject
calibration gas at a rate of 0.5 – 1.0 liter per minute.
Ensure the transmitter is functioning properly as indicated by the status LED and current output.
1.
Enter the main menu by selecting/activating any key to get the “enter main menu” prompt, then
activate switch 1 to select “yes”.
2.
When “Calibrate Sensor?” is displayed, activate the enter key (switch 3).
3.
When “Calibrate Sensor #1?” is highlighted, activate the enter key (switch 3) if this is the sensor
to be calibrated.
4.
If sensor #2 is to be calibrated, select the down arrow key (switch 2) to scroll to “Calibrate Sensor
#2?”
5.
Select the desired sensor to be calibrated (1 or 2) by activating the enter key (switch 3).
6.
Select “YES” with switch 1 to confirm the selection, and then apply clean air (zero gas) from
canister when “Apply Clean Air” is displayed. Ensure no contaminant gases are around if
ambient air is being used.
7.
Select “Z & Span” using switch 1 for normal (full) calibration. “Setting zero” will be displayed as
the sensor is being zeroed.
8.
Apply 50% calibration gas (* or % cal. gas value chosen) when prompted.
9.
The display will show “Spanning” with the gas value (%LEL or PPM depending on the sensor) as
the gas is detected.
10.
Remove the calibration gas when “Remove Cal Gas” is displayed.
11.
“Cal Complete” will be displayed when calibration is complete.
12.
Apply zero gas (clean air) to purge system. This is particularly important when using long tubing.