Biosystems PhD Ultra Reference Manual - page 16
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If the instrument is operated in the “Text Only” mode
an “OK” message will be displayed as long as an
alarm set point has not been exceeded. If the
readings exceed a pre-set alarm level, the message
changes from “OK” to a numerical reading, the LED
alarm light flashes, and the audible alarm sounds.
2.1.3 Other start-up screens
Several additional screens may be shown under
some circumstances. Usually the screen message
is self-explanatory.
2.1.3.1 “Self-adjusting” or “Correcting”
In some cases the PhD Ultra may detect an
electronic fault or need for adjustment when first
turned on. A screen will indicate the nature of the
fault. If the instrument is capable of correctly
adjusting itself a screen will indicate “Self Adjusting”
or “Correcting”. When the correction has been
successfully completed the instrument will continue
the self-test and start-up sequence.
2.1.3.2 “Non-standard alarms”
If the instrument determines that dangerously non-
standard or custom oxygen or LEL combustible gas
alarms have been selected, the LCD will display the
message “Non-Standard Alarms” at start-up. The
LCD will display the alarm settings for the affected
sensors.
Press the mode button to proceed with the non-
standard settings.
Note: Factory default settings may be easily
restored at any time. The procedure for
restoring factory default alarm settings is
discussed in Chapter 4.
2.1.3.3 “Needs Cal”
Biosystems EEPROM equipped “smart” sensors
automatically identify themselves to the PhD Ultra in
which they are installed. The PhD Ultra is aware
any time sensors are added, deleted, changed or
replaced. Any time a change is made to the
sensors, the PhD Ultra will display the message
“Needs Cal” followed by a list of the affected
sensors. This is an indication that the accuracy of
the affected sensors should be verified by exposure
to known concentration test gas before further use.
Following a “Needs Cal”
warning, the PhD Ultra should not be put back
into service or used until the accuracy of any
affected sensor has been verified by exposure to
the appropriate known concentration test gas.
The “Needs Cal” warning message may be
acknowledged (and silenced) by pressing the mode
button.
2.1.4 Turning the PhD Ultra off
Hold the mode button down for three seconds to
turn the instrument off. In order to prevent
accidental shut downs, the mode button must be
depressed for a full three seconds in order to turn
the instrument off. After three seconds (marked by
three beeps of the audible alarm) the LCD display
will display the message "Release button”.
If the button is released prior to the display of the
"Release button" message, the instrument will not
turn off.
After the button is released the LCD display will
save intrument data and then shut down
The shutdown sequence is complete when the
meter display blanks out in about ten seconds.
2.2 Operating
modes
The PhD Ultra offers a choice of three modes of
operation, "Text Only”, "Basic”, and "Technician”.
Mode selection is a function of how much
information is required, the skill level of the user,
and the nature of the job.
Regardless of operating mode selection, anytime
the PhD Ultra is on it is remembering the peak
readings of all gases measured, and is calculating
both Time Weighted Averages and Short Term
Exposure Levels for any toxic gas sensors installed.
Regardless of operating mode, the PhD Ultra will go
into alarm whenever an alarm set point is exceeded.
An alarm condition occurs when one of the sensor
readings exceeds a pre-set alarm level. When an
alarm condition occurs, the current gas readings
screen will change to reflect the new gas value, the
LED alarm lights will flash, and the audible alarm
will sound.
2.2.1 Text Only mode
The simplest mode of operation is the "Text Only"
mode. In this mode, during normal operation, the
LCD screen does not display numerical readings,
only the indication "OK”.
An alarm condition occurs when one of the sensor
readings exceeds a pre-set alarm level. The
indication will change from "OK" to the numerical
gas value that is registered by the instrument. The