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6.
Operation
6.1
Instrument Setup
6.1.1 Mounting Suggestions
CAUTION
6.1.2 Surveys
Maximum depth for the OBS-5+ is limited by the installed
pressure sensor. If the maximum depths are exceeded,
the pressure sensor will rupture and the housing will flood.
The depth limits are listed in TABLE 6-1.
TABLE 6-1. Working and Maximum Depths
Pressure Sensor
Working Depth
5 Bar
0 to 50 meters
10 Bar
0 to 100 meters
20 Bar
0 to 200 meters
(1 Bar = 10 dBar ≅ 10 meters of fresh water)
The following precautions should be followed to ensure the unit can function
properly and is not lost or damaged.
•
Always orient the unit so that the OBS-5+ sensor "looks" into water clear
of reflective surfaces.
•
Pad the endcaps that contact metal with electrical tape, neoprene, or
expanded polyethylene tubes.
•
Never mount the instrument by its endcaps or attach anything to them.
This could a cause a leak.
The OBS-5+ will usually be towed with a cable harness for surveys. The serial
cable can tow the OBS-5+ without a depressor weight or vane as long as the
connector is strain relieved. Strain relief can be provided by attaching the
cable to the stainless steel housing (FIGURE 4-1) with a cable grip and a
length of 3 mm (1/8 in) wire rope. Install a cable clamp with a 0.5 m wire rope
to the serial cable, and clamp the wire rope to the pressure housing with two
stainless steel hose clamps, providing a small loop of slack cable to absorb
towing forces. The unit can be powered with an external battery, as shown on
FIGURE 6-1, and the serial output can be transmitted by either RS-232 or
RS-485 protocols. The latter protocol is recommended for cable lengths
greater than 25 m. An RS-485/232 serial converter is provided with each unit.
An RS-232 to USB converter is an available option.
OBS-5+ System
Maximum Depth
75 meters
150 meters
300 meters
7
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