Biosystems PhD Ultra Reference Manual - page 13
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pack is momentarily removed or replaced with
another it will be necessary to manually turn the
PhD Ultra off if the instrument is not going to be
put to immediate use.
1.9.2.1 NiCad battery pack
The rechargeable NiCad battery pack is designed to
provide up to 12 hours of continuous use. The
NiCad battery pack is a sealed assembly and may
not be disassembled in the field.
The NiCad battery may be recharged while the pack
is installed in the instrument, or the battery pack
may be removed from the instrument for separate
recharging in the PhD Ultra Fast Charger.
Fully assembled NiCad battery packs may be
removed or replaced while the instrument is being
used in a hazardous location.
To maintain intrinsic safety,
the PhD Ultra may not be located in a hazardous
location while being recharged. If the NiCad
battery pack is being recharged separately from
the instrument, then the PhD Ultra Fast Charger
must not be located in a hazardous area.
1.9.2.2 Disposable alkaline battery pack
The PhD Ultra may also be equipped with a battery
pack designed to hold 3 AA disposable alkaline
batteries. A set of alkaline batteries will provide up
to 12 hours of continuous use. The alkaline battery
pack is removed in the same manner as the NiCad
pack. The alkaline pack must be removed from the
instrument in order to replace expended batteries.
The alkaline pack is opened by removing the
Phillips screw on the bottom of the battery pack,
then squeezing the ends of the pack and gently
removing the cover.
Only fully assembled alkaline
battery packs may be removed or replaced while
the instrument is being used in a hazardous
location. Alkaline battery packs may not be
opened and alkaline batteries may not be
replaced while the battery pack is located in a
hazardous area.
Battery replacement and charging procedures
are covered in greater detail in chapter 2.
1.9.3 Continuous sample draw pump
An optional slip-on, motorized sample-draw pump is
available for situations requiring continuous "hands
free" remote monitoring. The PhD Ultra’s Intrinsic
Safety Classification by UL and CSA includes the
use of the PhD Ultra pump.
The pump contains a pressure sensor that detects
when water or other fluids are being drawn into the
unit, and immediately acts to shut off the pump in
order to protect the sensors, pump, and other PhD
Ultra components from damage.
Pump status is continuously monitored by the
microprocessor. A flashing “P” in the upper left
corner of the instrument display indicates when the
pump is attached and operating properly. Low flow
or other pump fault conditions activate an audible
alarm and cause the display of the appropriate
explanatory message.
The sample pump is powered directly by the PhD
Ultra battery. Both alkaline and NiCad battery packs
are designed to provide at least 8 hours of
continuous pump operation even when the
instrument is operated in low light conditions and the
backlight is continuously lit.
1.10 PhD Ultra design components
Figure 1.10.1. Major PhD Ultra Features (Top and
Front Surfaces)
Figure 1.10.2. Major PhD Ultra Features (Bottom)
(1) Case: The instrument is enclosed in a solid,
stainless steel-impregnated polycarbonate case.
A water-resistant PVC gasket between the upper
and lower sections of the case protects against
leakage or exposure to liquids.
(2) Front face: The front face of the instrument
houses the meter display and alarm lights.