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(4) Press the mode button three times within two
seconds. This will "wake up" the instrument
from normal operation, and put it into the “Auto-
Calibration” mode. A screen will briefly display
the message “One button Auto-Calibration”.
This screen will be followed by the "Zero
Calibration Adjustment” screen.
This screen also includes a timer that counts
down the number of seconds left to initiate the
adjustment.
(5) Press the mode button within five seconds to
initiate the fresh air adjustment. An information
screen will be briefly displayed while the
adjustments are being made, and another when
the adjustments have been completed.
(6) If the mode button is not pushed within five
seconds a fresh air zero adjustment will not be
made. A message screen indicating that the
zero values have not been changed will be
briefly displayed, and the instrument will return
to normal operation.
3.4.1.1 Reading “Too High” or “Too Low” for
zero adjust
To reduce the chances of the PhD Ultra being
inadvertently zero calibrated in contaminated air,
only small adjustments are allowed through the use
of the “One Button” auto-zero sequence. If the
necessary adjustments are too large the display will
indicate the sensor (or sensors) affected, and a
message screen will indicate that the reading is “Too
Low” or “Too High” for zero adjustment. In this case
the instrument must be fresh air zeroed using the
“CAL” button on the instrument keypad and
procedures discussed in Section 3.5.1 of this
manual.
Once the instrument has been successfully zeroed
using the “CAL” button, subsequent calibration
adjustments may be made using the mode button
and “One Button Auto Calibration” logic discussed in
this section.
3.4.2 “Span” auto-calibration sequence
After successful completion of the “zero” auto-
calibration adjustment the display will show the
“Span Calibration Adjustment” screen.
This screen also includes a timer that counts down
the number of seconds left to initiate the
adjustment.
Note: If the MODE button is pressed at any time
prior to completion of the calibration, the
calibration procedure will be cancelled, no
adjustments will be made and the instrument
will return to normal operation.
Wait at least 3 minutes after
turning the instrument on to allow sensor
readings to stabilize fully before initiating any
calibration procedures. Failure to wait three
minutes before initiating calibration procedures
may lead to inaccurate and potentially
dangerous readings. If a sensor has just been
replaced, the stabilization period may be longer
(see the chart in section 5.1).
(1) Press the mode button within 5 seconds to
initiate “span” auto-calibration. A screen will
instruct you to “Apply Gas”.
The instrument will continue to display this
screen until it determines that calibration gas
has been applied. (Auto-span may be canceled
at any time during the procedure by pressing the
mode button.)
(2) Attach the cylinder of calibration gas, regulator,
short section of tubing and calibration adapter to
the PhD Ultra as shown in Figure 3.4.2.
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.
CAUTION:
The use of regulators with on/off
valves may introduce contaminants into the gas
cylinder and may lead to the breakdown of
reactive gases prior to the cylinder expiration
date. Biosystems strongly recommends the use
of continuous fixed-flow regulators for all
calibration procedures.
Use of non-standard
calibration gas and/or calibration kit
components when calibrating the PhD Ultra may
lead to dangerously inaccurate readings and
may void the standard Biosystems warranty.
