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LED alarm lights will flash and the audible alarm will
sound during an alarm condition.
PhD Ultra alarms are normally self-resetting. When
readings drop back below the pre-set alarm levels,
the screen returns to the "OK" indication, and visual
and audible alarms cease.
In Text Only mode, press the mode button to toggle
between the two available screens. The first screen
is the current gas readings screen, which in Text
Only mode will show OK unless an alarm set point
has been exceeded. Press the mode button to
access the runtime screen, which shows the time,
battery voltage, running time for the instrument
since last turned on (in hours and minutes), and
temperature (in both Fahrenheit and Centigrade).
Note: It is not possible to make calibration
adjustments while the PhD Ultra is operated in
the Text Only mode. The PhD Ultra must be
operated in either Basic or Technician mode in
order to initiate the “Auto-Calibration”
sequence.
2.2.2 Basic
mode
The "Basic" mode of operation provides the user
with numerical readings at all times, but keeps
operation of the gas detector simple.
In Basic mode the user has access to two "screens"
of information. Press the mode button to toggle
between the two available screens. The first screen
is the current gas readings screen, which will always
provide numerical readings in Basic mode.
Press the mode button to access the runtime
screen, which shows battery voltage, running time
for the instrument since last turned on (in hours and
minutes), and temperature (in both Fahrenheit and
Centigrade).
In Basic mode it is possible to enter the “Auto-
Calibration” mode in order to make zero and span
calibration adjustments. This feature is not enabled
when the instrument is operated in the Text Only
mode.
Calibration procedures are discussed in detail in
Chapter 3.
A
n alarm condition occurs when one of the sensor
readings exceeds a pre-set alarm level. The
numerical reading changes to reflect the new value,
the LED alarm light flashes, and the audible alarm
sounds.
PhD Ultra alarms are normally self-resetting. When
readings drop below the pre-set alarm levels, visual
and audible alarms cease, and the instrument
resumes normal operation.
2.2.3 Technician
mode
The "Technician Mode" provides access to all
advanced functions and displays, including the
automatic calibration subroutines.
Calibration procedures are discussed in detail in
Chapter 3.
In Technician mode, following completion of the
start-up and self-test sequence, the current gas
readings screen will be shown with numeric displays
for all sensors. An alarm condition occurs when one
of the sensor readings exceeds a pre-set alarm
level. In an alarm condition, the numerical readings
change to reflect the new value, the LED alarm light
flashes, and the audible alarm sounds.
PhD Ultra alarms are normally self-resetting. When
readings drop back below the pre-set alarm levels,
visual and audible alarms cease, and normal
operation of the instrument resumes.
Press the mode button to scroll through the
numerous screens of information available in
Technician mode.
2.2.3.1 Peak readings
From the current gas readings screen in Technician
mode, press the mode button once to display the
“Peak” readings for the gases being measured.
These readings represent the highest (or in the case
of oxygen highest and lowest) values registered by
the instrument during any period of operation. Peak
readings are updated on a second by second basis.
The PhD Ultra will automatically cycle between two
peak reading screens, one for oxygen, and one for
the other gases being measured. The oxygen peak
reading screen shows both the high (HI) and low
(LO) readings.
2.2.3.2 STEL readings
Press the mode button again to display the “STEL”
readings for the toxic sensors currently installed.
The STEL (Short Term Exposure Limit) for a
particular toxic gas is the maximum average
concentration to which an unprotected worker may
be exposed in any 15 minute interval during the day.
The STEL value displayed by the PhD Ultra is the
