GxT Ferret 54 ENGINE DIAGNOSTIC CENTER - Manual (Page 87)

Following this, air is drawn through the
sample system to determine the flow
normally delivered during sampling. The
sample hose should be placed where it can
freely draw fresh air. No sharp bends or
restrictions should be allowed to inhibit the
flow of air.
When prompted by the display, begin the
flow of Calibration Gas.
Slowly adjust the regulator so that the bar
graph ends between the marks shown on the
display.
Press NEXT when the graph is between the
marks.
While the Gas is flowing, a high-pitched
whine or buzz may be heard. This is from the
action of the check valve and is not an
indication of a problem.
After the calibration is completed, a prompt
will appear to turn off the calibration gas.
Turn the calibration gas bottle valve off (fully
clockwise), and adjust the regulator to off
(fully counterclockwise).
If the flow is not in the proper range, or the
Gas sample measurement does not come
close to the selected Calibration Gas values,
a warning message will appear and the
Calibration process will not be completed.
CALIBRATE
To maintain the accuracy of the Gas
Detector, periodic calibration with known
concentrations of gas are required. Monthly
calibration is recommended for general
diagnostic use. State mandated programs
may require specific calibration schedules.
Preparation
Be sure that the calibration gas bottle valve
is off (fully clockwise), and that the hose from
the regulator to the Gas Detector is
connected. Adjust the regulator to off (fully
counterclockwise).
Procedure
The calibration procedure begins with
selection of the Calibration Gas
concentrations to be used. A Calibration gas
selection screen will appear. Refer to the tag
on the bottle, and select the matching
concentration from the list.
HC(Prop) CO CO2
BAR84 : 600 1.6 11.0
BAR90L: 300 1.0 6.0
BAR90H: 1200 4.0 12.0
Press NEXT and select the proper NOx
concentration.
Choose NOx Concentration
2000 ppm
1000 ppm
N O N E
The concentration numbers marked on the
calibration gas bottle may not match one of
the screen choices exactly. If that is the
case, and the numbers are close, use the
screen choice that most closely matches.
The calibration continues with the ZERO
process; air is drawn through an internal filter
to adjust for zero concentration levels.
8-2
T
HIS IS THE ONLY TIME THE VALVE ON THE
C
ALIBRATION
G
AS BOTTLE
SHOULD BE OPENED
!
A
LLOWING
C
ALIBRATION
G
AS TO FLOW
DURING
ZERO
ING OR SAMPLING
MAY RESULT IN
ERRORS!!