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The P-DORT has two modes
of basic operation. Firstly, like a standard DORT, it responds
to securely coded acoustic commands from the surface in
the LF (9-13 kHz) frequency band.
Secondly, it can be pre-programmed
prior to deployment to automatically release when it reaches
a certain depth. This allows heavy items, such as submarine
cables for example, to be lowered precisely to the seabed
and then the lowering apparatus recovered after an automatic
release. The acoustic ranging function within the P-DORT
can also be used to relocate the equipment should the lowering
cable fail.
There are two options for
setting the 'release at depth' option. In the primary mode,
a depth is set and once the unit passes that depth, the
unit will immediately release. The secondary mode allows
for shallower depth to be set for when the primary release
depth has been erroneously set to greater than the actual
water depth. Then, if the unit passes that depth but remains
stationary (i.e. on the seabed) for a specified time, it
will release.
The Windows-based control
software for the automatic depth mode runs on a standard
PC running Windows 98, ME, 2000 or XP and is connected to
the P-DORT using a serial cable and interface box
Technical Specifications
| Feature
|
Type 8048-03 |
| Depth Rating |
7,000 Metres |
Operating Frequency
|
LF (7.5–15kHz) |
| Transducer Beamshape |
Hemispherical |
| Transmit Source Level (dB
re 1µPa @1m) |
190dB Alkaline, 184dB Lithium |
| Receive Threshold (dB re
1µPa) |
85dB |
Safe Working Load (4:1)
|
2,500kg |
| Max Safe Release Load |
2,500kg |
| Breaking Load |
10,000kg |
| Battery Life (Listening) |
Alkaline
Lithium
Long-life Lithium
3 months 8
months 12
months
|
| Mechanical Construction |
Ferralium 255 |
| Dimensions (LxDia) |
868mm (34.2”) x 145mm (5.7”) |
| Weight in Air |
39.2kg |
| Weight in Water |
30.2kg |
| Deck Unit |
Type 7667 LF Lightweight Command
Unit
|
Safe Working
Load - The maximum recommended working load. This is
set as a quarter (1/4) of the Breaking Load and allows
for factors such as corrosion, fatigue, shock loads,
harmonic loads, manufacturing defects and material defects.
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Release Load
- The maximum in-line load that the whole assembly can
release whilst guaranteeing safe and reliable operation.
Note that as the load is released in water, this is
determined by the maximum upthrust from the buoyancy.
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Breaking Load
- The load that induces structural failure in one or
more parts of the instrument causing the load to part
from the release mechanism
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Features
:-
- Acoustic and automatic 'Release at Depth'
operating modes
- Safe Working Load of 2½ Tonnes
(Options for heavier loads)
- Depth rated to 7,000 metres
- Highly reliable, proven release mechanism
- Up to 12 months deployment
- Excellent corrosion resistance - Ferralium
255
- Compact and rugged design
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