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PhD Ultra alarms are normally self-resetting, which
means that the alarms cease as soon as reading
drops below the alarm set point.
PhD Ultra alarms can be configured so that they
"latch”. In the latched condition, once an alarm
occurs both visual and audible alarms continue to
sound even after the atmospheric hazard has
cleared. The instrument must be manually reset by
pressing the mode button. Pressing the mode
button silences the alarms and restores normal
operation.
Press the “+” or “-” key to change the alarm latch
setting.
4.3.5 OK Latch - Text Only mode
To access the OK latch settings, first enter the
configuration set up choices menu as described in
section 4.3.1. Then press and release the “CAL”
button to advance to the “OK Latch” screen.
If an alarm condition occurs and clears while the
PhD Ultra is operated in text-only mode with the OK
latch enabled, the instrument will continue to display
numeric readings for the sensor that was in alarm.
This allows the user to know that an alarm condition
was present during the current operating session.
If an alarm condition occurs and clears while the
PhD Ultra is operated in text-only mode with the OK
latch disabled, the PhD Ultra will automatically
return to the OK display for the sensor that was in
alarm.
Use the “+” or “-” keys to change the “OK Latch”
setting.
4.3.6 Security
beep
To access the security beep settings, first enter the
configuration set up choices menu as described in
section 4.3.1. Then press and release the “CAL”
button to advance to the “Security Beep” screen.
The security beep screen allows the PhD Ultra to be
programmed to emit an audible alarm "beep" on a
specified interval while the instrument is in
operation. This periodic beep serves as a reminder
that the instrument is on.
Use the "+" and “-” buttons to turn the security beep
on or off.
Once the security beep is turned on the screen will
show an additional indicator message showing the
minutes and seconds between beeps. Use the "+"
and "-" keys to set the interval. (Setting the interval
to “0” will turn the security beep off.)
4.3.7 Low temperature alarms
To access the low temperature alarms settings, first
enter the configuration set up choices menu as
described in section 4.3.1. Then press and release
the “CAL” button to advance to the “Low Temp
Alarms” screen.
The PhD Ultra includes both high and low
temperature alarms for all sensors recognized by
the instrument. The alarm setpoints are pre-
programmed into the individual sensor EE-proms
and may not be modified in any way, but the high or
low temperature alarms for all recognized sensors
can be enabled or disabled depending on the needs
of the user.
Press the “+” or “-“ key to change the setting.
4.3.8 Operating
mode
To change the operating mode, first enter the
configuration set up choices menu as described in
section 4.3.1. Then press and release the “CAL”
button to advance to the “Operating Mode” screen.
Use the “+” or “-” buttons to choose the operating
mode of the instrument when next turned on in
normal operation.
See section 2.2 above for a detailed description
of operating modes and functions.
4.3.9 Combustible sensor setting
The PhD Ultra may be configured to show
combustible gas readings in terms of percent of LEL
(Lower Explosive Limit) or in terms of the percent by
volume of methane (CH
4
).
With the PhD Ultra configured to read in terms of
percent by volume of methane (CH
4
), the LEL
sensor must be calibrated to the actual percent by
volume of methane used in Biosystems calibration
gas cylinders, not to the %LEL value given on the
label. The actual percentage by volume of CH
4
will
be stamped in indelible black ink on the side of the
cylinder body. For example, Biosystems popular all-
in-one mix, part number 54-9044E, with 50% LEL
propane equivalent will list ±1.62% CH
4
on the side
of the cylinder body. In this case, the percent by
volume CH
4
calibration gas value should be set to
1.62%.
To change this setting do the following:
(1) Move to the “Instrument Setup” screen as
described in section 4.3.1 and use the ‘CAL’ key
