Biosystems PhD Ultra Reference Manual - page 12
12
1.6.4.5 Down-scale or negative reading alarms
Significantly negative or “down-scale” readings
cause the activation of PhD Ultra audible and visual
alarms. Downscale alarm settings are assigned at
the factory on a sensor-specific basis. For most
toxic sensors the downscale alarm is set to negative
one-half of the TWA alarm currently installed. (As
an example, if the TWA alarm is set at 15 PPM,
readings of negative 7.5 PPM would activate this
alarm.)
1.6.4.6 Temperature out of range
The PhD Ultra design includes a temperature sensor
located inside the instrument case in the area where
the gas sensors are located. The microprocessor
automatically adjusts the sensor output to
compensate for temperature changes in the area in
which the instrument is being operated. If the
temperature falls outside the range for which the
instrument can fully compensate, the current gas
reading screen will show a “T” in place of the
reading for the affected sensor.
1.6.4.7 Other electronic safeguards
Several automatic programs prevent tampering and
misuse of the PhD Ultra by unauthorized persons.
Each time the detector is turned on, an electronic
self-test is performed that assures the user of proper
performance. The sensors, LED alarm lights, and
audible alarm are automatically tested whenever the
PhD Ultra is turned on. The battery is monitored
continuously for proper voltage. Detected electronic
faults cause the activation of the appropriate alarms
and the display of the appropriate explanatory
message.
1.6.4.8 Security beep
The PhD Ultra may also be set-up to periodically
“beep” to indicate that the instrument is turned on.
Adding a security beep as well as making use of
other optional set-up choices is done by using the
four buttons on the instrument keypad located under
the belt clip on the back of the instrument housing.
Chapter 4 describes PhD Ultra advanced
technical features in greater detail.
1.7
Instrument Firmware Requirement
for Compatibility with the IQ
System
Biosystems IQ System is an automated calibration
station coupled with a data management system.
To be compatible with the IQ System, the PhD Ultra
must have instrument firmware version 3.40 or
higher.
Instrument firmware version is given immediately
after the PhD Ultra is turned on.
1.8
Classification for intrinsic safety
The PhD Ultra is Classified by Underwriters
Laboratories, Inc. and the Canadian Standards
Association as to Intrinsic Safety for use in
Hazardous Locations Class I, Division 1, Groups A,
B, C, & D. This means that the PhD Ultra has been
successfully tested for safety in combustible gas /
air (21 % oxygen) mixtures.
1.9 Options
1.9.1 Sensors
The PhD Ultra can be configured to detect oxygen,
combustible gas, and up to two toxic gases. The
sensor configuration may be changed in the field, or
specified at the time of purchase. Calibration is
required after any sensor change.
1.9.2 Batteries
PhD Ultra batteries are housed in removable snap-
in battery packs. Two types of battery packs
(rechargeable NiCad and alkaline) are available for
use. Battery packs are clearly labeled as containing
either NiCad or disposable alkaline batteries.
Battery packs are interchangeable. Battery packs
can be replaced while the instrument is in the field.
It is not necessary to open the instrument case to
replace the battery pack that is currently installed.
The PhD Ultra should be turned off before changing
or replacing battery packs. A spring-loaded catch
holds the battery pack firmly in place in the
instrument chassis. To remove the battery pack first
pull back on the spring loaded catch, then pull the
battery pack upward and backwards (towards the
rear of the instrument).
To replace the battery pack, seat the notch in the
front of the battery pack housing to the matching lip
in the PhD Ultra instrument case. When the battery
pack is properly positioned, press down gently on
the rear of the battery pack to engage the spring
loaded catch.
Do not store or leave your PhD Ultra with the
battery pack removed.
Toxic sensors must be allowed to “warm-up” or
stabilize when first installed in an instrument. When
there is a power interruption (as when the battery
pack is removed) the toxic sensors begin to
destabilize. The longer a toxic sensor is without
power the longer it will take for re-stabilization.
See the sensor stabilization chart in section 5.1
for more details.
Note: The PhD Ultra is designed to turn itself on
whenever a battery pack is removed and
replaced. This is to ensure that in the event of
an interruption in power the instrument is not
accidentally turned off. Any time the battery