Page 346 - Offshore Electrical Engineering Manual

Ballast Control: Basic Control Features 333

their work is such that they frequently require changes of draught, list and trim,
often in a very few minutes’ notice. They can be working in close proximity to other
vessels, carrying out combined operations in the open sea in seriously bad weather
conditions.

BALLAST CONTROL: BASIC CONTROL FEATURES
The central ballast control station should be located above the damage waterline
and in a space not within the damage penetration zone, adequately protected from
weather. The following control and indicating systems should be provided where
applicable:

1. bilge and ballast pump control system
2. pump status indicating system
3. valve control system
4. valve position indicating system
5. tank level indicating system
6. draught indicating system
7. heel and trim indicators
8. power availability indicating system (main and emergency)
9. hydraulic or pneumatic pressure indicating system
10. monitoring systems, e.g., machinery alarm, fire and gas detection system.

To ensure that uncontrolled transfer of ballast water will not continue upon loss
of power, ballast tank valves are to close automatically upon loss of power, or be
provided with an equivalent (or better) facility.
The control and indicating systems should function independent of each other so
that a failure in any one system will not affect the operation of the other systems. The
ballast pump and ballast valve control systems should be arranged so that the loss of
any one of their components will not cause the loss of operation in the other pumps
or valves.
In addition, some facility to calculate the effects of tanks and flooded compart-
ments is advised, especially in emergencies where the ballast control operator may
need to act quickly to avoid serious listing or capsizing. As with any other safety
critical system, the ballast control system will require to be fed from a secure elec-
trical supply (uninterruptible power supply) and located in or near the main control
room in a pressurised (nonhazardous) protected compartment.
It is vital that the ballast control panel is adequately illuminated after the failure
of normal lighting (Fig. 6.1.4).