10
Use of these procedures is reserved for
authorized personnel.
1.5 Instrument
identifiers
The PhD Ultra includes two built-in instrument
identifiers: the Instrument ID and Serial Numbers.
The instrument serial number is assigned at the
factory and is shown on the label on the back of the
instrument case. It is also permanently stored in the
instrument memory and is displayed in the startup
screens. The instrument serial number may not be
modified by the user.
The instrument ID number is an identifier that is
assigned by the user. For instructions on changing
the instrument ID number see section 4.3.3.
1.6 Alarm
logic
PhD Ultra gas alarms are user adjustable and may
be set anywhere within the range of the sensor
channel. When an alarm set point is exceeded a
loud audible alarm sounds and a bright red LED
alarm light flashes for each sensor that is in alarm.
PhD Ultra gas alarms are normally self-resetting.
When readings drop back below the pre-set alarm
levels, the instrument returns to normal operation,
and the visual and audible alarms cease.
It is possible to set PhD Ultra gas alarms 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 then be manually
reset before the alarms are silenced.
1.6.1 Atmospheric hazard alarms
The PhD Ultra portable gas
detector has been designed for the detection of
deficiencies of oxygen, accumulations of
flammable gases and vapors, and
accumulations of toxic vapors. An alarm
condition indicating the presence of one or
more of these potentially life-threatening
hazards should be taken very seriously.
In the event of an alarm
condition it is important to follow established
procedures. The safest course of action is to
immediately leave the affected area, and to
return only after further testing determines that
the area is once again safe for entry. Failure to
immediately leave the area may result in serious
injury or death.
A rapid up-scale reading
followed by a declining or erratic reading may
indicate a hazardous combustible gas
concentration that exceeds the PhD Ultra’s zero
to 100 percent LEL detection range. Failure to
immediately leave the area may result in serious
injury or death.
The combustible gas alarm is activated when the
percent LEL (Lower Explosive Limit) gas
concentration exceeds the pre-set alarm point.
Two oxygen alarm set points have been provided;
one for low concentrations associated with oxygen
deficiency and one for high concentrations
associated with oxygen enrichment.
Three alarm set points have been provided for each
toxic gas monitored; TWA (Time Weighted
Average), STEL (Short Term Exposure Limit), and
Ceiling.
Appendices A and B discuss alarm levels and
factory default alarm settings. The procedure
for adjusting alarm set points is discussed in
Chapter 4.
1.6.2 Sensor overrange alarms
If a sensor is exposed to a concentration of gas that
exceeds its established range, the PhD Ultra will go
into alarm. If the PEAK alarm is enabled, the
overrange alarm appears exactly the same as a
PEAK alarm, that is, the LED over the gas name
and the audible alarm are activated. If the PEAK
alarm is disabled, the overrange alarm is indicated
by flashing the numerical reading on and off while
the LED over the gas name and the audible alarm
are also activated. This applies to all toxic sensors.
If the LEL sensor goes into overrange alarm the
display will alternate between an “X” for the LEL
reading and an “LEL SENSOR OVER LIMIT”
message.
In the event of an LEL
overrange alarm the PhD Ultra must be turned
off, brought to an area that is known to be safe
and then turned on again to reset the alarm.
Note: The PhD Ultra features automatic warning
against LEL sensor response failure due to lack
of oxygen. When oxygen levels fall below 10%
of gross volume, the PhD Ultra will intermittently
display a message indicating that O
2
is too low
for LEL to operate.
1.6.3 Low battery alarms
The PhD Ultra may be equipped with either a
rechargeable NiCad or an alkaline battery pack.
Alarms will be activated whenever battery voltage is
too low to allow the safe operation of the instrument.
The PhD Ultra is designed to automatically
determine which type of battery pack has been
installed, and use the appropriate low battery alarm
settings.
