OTT Hydrolab DS5, User Manual

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35
Deployment
5.2.4 Minimum Flow Requirements
When deploying the multiprobe in waters flowing at less than one foot per second
(0.333 mps), a circulator option may be used for additional flow in order to achieve reliable
Clark Cell dissolved oxygen sensor readings. The circulator is activated via Hydras 3 LT
software or the Surveyor.
Turning the circulator on or off will help during profiling and logging D.O. with a Clark Cell
Sensor, depending on the flow rate of the water at the site. If insufficient flow rate is
noticeable, turn the circulator on. Turn the circulator off to extend battery life when data is
not needed for an extended period of time. Turn the circulator on when logging data in
unattended mode and need to have sufficient flow for accurate measurements, note that
this will reduce multiprobe battery life.
When the multiprobe is powered, it takes time to warm-up. The warm-up time refers to the
time a sensor will be ready to record accurate data. Warm-up time will vary according to
the sensors being used and field conditions (e.g. temperature).
5.2.5 Non-submersible Deployment
DANGER
Do not let the flow cell pressure exceed 15 psig. Higher pressure can burst the flow
cell, possibly causing serious bodily injury to oneself and/or others.
For process or pump-through situations, attach the low-pressure flow-cell to the
mulitprobe. This configuration allows studying the water without submerging the
multiprobe. The flow cell replaces the DS storage cup or MS cup (
Figure 13 ). When
measuring D.O. with a Clark Cell Sensor inside a flow cell, the manufacturer recommends
using a circulator in conjunction with the sensor. For use without a circulator, use a flow
rate of more than 4 liters per minute. A ½-inch hose is required for the MS flow cell and a
¾-inch hose for the DS flow cell.
Filter debris from the feed line, if necessary. If possible, invert the multiprobe, so that
bubbles will float away from the sensors and out the port on the bottom of the flow cell.