JRC JLN-900, Инструкция по установке и эксплуатации

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2. Transducer location requirements
To achieve proper performance of the speed log, special care must be taken to find the best
area in respect of water streaming under the hull and the Transducer (CFT-780) sensor head.
Selecting correct Transducer location shall be done in co-operation with
JRC .
It is recommended to send General Arrangement (GA) drawings, showing suggested
Transducer installation, to
JRC for review and comments. The comments given will only
refer to the hydro-dynamical requirement and not the inside design, such as installation height,
access to closing valve or any inside obstacles that might occur and jeopardise the function or
maintenance.
Following rules must then be considered:
1. For more detailed installation advices please read the complete instruction.
2. The Transducer should be installed in the foremost part of the vessel as close as possible
to the keel line.
3. The bottom Sea Valve shall always be installed perpendicular to the ship’s horizontal
plane. Recommended vertical installation angle 0 - 2 degrees in the forward/longitudinal
direction and +/- 2 degrees in the sideway/athwardship direction.
4. The Sea Valve arrangement and Transducer cable are not intended for submerged
mounting in a water filled tank. If no other alternative is available a separate watertight
(W.T.) compartment must be arranged housing the Sea Valve/Transducer assembly. The
cable must be run in a watertight pipe conduit, connecting directly from the W.T.
compartment to free/dry space where NJC-80 is normally installed.
5. The compartment in which the Transducer is installed may be sealed by a manhole or
hatch but the compartment must always be accessible for service.
6. The Transducer cable must be installed in an accessible way to allow
retraction/dismounting incase of service or replacement of a defective Transducer.
Excessive cable length shall be left uncut and coiled, i.e. one coil/loop close to the Sea
Valve/Transducer and remaining length close to NJC-80.
Do not cut the cable! Warranty is void if cable is cut or violated.
7. Sufficient headroom must be available at the Transducer position to allow for its
installation and removal (see details for appropriate Bottom Parts).
8. On tankers the Transducer location is not to be within the Ex–area. The Transducer must
never come in contact with explosive cargo oil/fuel oil/gas or other hazardous cargo.
9. The Transducer cable shall run directly to the speed log NJC-80 and must never be cut
off, shortened, extended or by any other mean passing through a junction box!
10. JLN-900 speed log operates with ultra-sonic frequencies of 145 - 155 kHz, and 3.8 MHz /
4.2 MHz. The Transducer location must be at least 2 metres from any echo sounder
transmitters or other similar acoustic devices generating the same type of frequencies.
11. The Transducer cable must be separated from other cables to minimise risk of interference.
The Transducer cable shall not share pipe with other cables.
12. In the vicinity of the Transducer location, the outside of the vessel must be free from
sudden projections, welding joints, steps and sharp edges. Special care must be taken that
no obstacles appear, especially forward of the Transducer. These conditions will cause
water turbulence, which may give unreliable speed readings from the system.