20
3.4.2 “Span” auto-calibration
sequence
After successful completion of the “zero”
auto-calibration adjustment the display
will show the message “SPAN MODE”.
↔
If the MODE button is not pushed within
five seconds a span calibration
adjustment will not be made, and the
instrument will be returned to normal
operation.
(1) Press the MODE button within 5
seconds to initiate “span” auto-
calibration. A screen will ask you to
“FLOW GAS”. The instrument will
continue to display this screen until it
determines that calibration gas has
been applied.
↔
Note: It is possible to exit the auto-
calibration mode at any time prior to
completion by pressing and holding
down the MODE button for 3 seconds
to turn the instrument off.
(2) Attach the cylinder of calibration gas,
regulator, short section of tubing and
calibration adapter to the Toxi Plus
detector.
Make sure the
regulator, cylinder seating surfaces
and threads are clean and dry before
attaching the regulator to the cylinder
of gas. Introduction of contaminants
through the regulator fittings may
alter or degrade the concentration of
the gas contained in the cylinder and
may lead to inaccurate and potentially
dangerous gas readings.
The regulator will automatically begin
flowing calibration gas as soon as it is
screwed into the cylinder of gas.
(3) The instrument will display the
sensor readings as they rise. When
they have stabilized at their highest
value, the instrument will note the
response and, if necessary, adjust the
readings to match the concentration of
gas being used to calibrate the
detector. (The instrument will beep as
the adjustment is being made.)
Calibration values
shown on the “Span Adjust” screen
as the sensor is adjusted must match
those appearing on the calibration
gas cylinder(s) that will be used to
calibrate the Toxi Plus. Non-matching
calibration gas and calibration gas
value settings will lead to inaccurate
and potentially dangerous readings.
If the concentration does not match it
will be necessary to assign a new
calibration gas concentration as
discussed in Chapter 4 before
continuing with the auto-span
adjustment.
(4) When span adjustment has been
completed, the display will show the
message “DONE”, after which the
instrument will return to the gas
indicator mode, and display the
current gas readings.
Note: Make sure the calibration
adaptor and all other fittings have
been removed from the detector
before it is returned to service.
3.5
Manual calibration
procedure
It is also possible to calibrate the Toxi
Plus manually using the four buttons on
the instrument keypad.
3.5.1 “Forced” fresh air
"zero" through keypad
buttons
Only perform the
“forced” fresh air calibration in an
atmosphere that is known to be free
