Principle of Design
The system design principle satisfies the IMO requirements for the bulk carriers as SOLAS Chapter XII Regulation 12 & 13.
IMO Resolution MSC 145(77)
IACS US S 24 & UI SC 180 & 179.
Additionally, the system design satisfies the requirements of IMO resolution A. 861(20). i.e
Apart from the above compulsory operations, the system provides additional features. These contribute to better and safer ship operation, i.e.
1. The water level height (in cm) is indicated, this helping the master to estimate the real cause of the water accumulation in the holds and the capability to differentiate between condensation from cargo or actual ingress from the sea.
2. Signals of any level alarm can be transmitted to the VDR. This feature should satisfy any relevant IMO requirement in the future.
3. In case an alarm signal isn’t acknowledged within a reasonable time period (about 60 sec.), it can be transferred to other spaces i.e. engine room alarm panel, general alarm, deck, duty officer cabin etc.
4. The system has the capability to monitor the vessel’s draughts (Fwd., Mid Port, Mid Std, Aft.), any time.
5. The system can be connected to a personal computer or main computer and direct to printer.
6. The system has the possibility to monitor more parameters depending of the kind of existing cargo (special customer requirements), such as holds’ temperature, humidity, quality of ventilation, etc.
Generally, the system’s characteristics are dynamic. Its potential may be increased on the basis of managers’ experience, charters’ requirements and shipping practice.
The system consists of an annunciation alarm panel that is usually installed in the navigation bridge area, a group of direct liquid contact pressure sensors, which are permanently installed in hold areas or elsewhere. The sensors are connected to the panel, by means of marine type cables.
The panel may be connected to other elements of ship equipment and be activated via or by the system i.e. (VDR, Engine room alarm panel, other computer etc). The electric current for pressure gauging is a low voltage of D.C 24 V and fluctuates from 4 mA, when the pressure is zero, to 20 mA, when the pressure corresponds to the full depth of the vessel. The signals are collected and protected by I/S ZennerBarriers on various analogue input units and are directed to the Programmable Logic Controller (PLC), where they are processed. The processed data, as well as logic decisions and controls, appear on the touch screen. Users may now interfere with the touch screen -a feed back type of data to PLC - in order to set up new parameters, insert new inputs and actions. The system is user friendly and does not require any special knowledge in automation from the user. Its operational design offers a high level of safety and security.
The touch screen can be dimmed in order not to interfere with the bridge environment. It will be automatically reenergized and light up once touched again or in the event of an alarm signal. In the latter case, the screen cannot be dimmed again until the cause that triggered the alarm is corrected.
The system’s interface consists of four basic screens and an optional one. The alarm listing screen, the bar graph screen, the ballast screen and the alarm settings screen. The optional screen is the ship’s draft screen.
1. Alarm listing screen
When an alarm is activated:
At the top of the screen a red colour text trailer will continuously move over a horizontal line, indicating the alarm point. The corresponding button and alarm level setting (L.L or H.L or Ballast Level) will flash. The “Alarm” indication will be added at the end of the right side alarm list, marking the position, the time of activation and the reset time. If the list is full, then every new alarm will be scrolled down on screen. If the button “View” is touched, the next screen appears.
2. Level indication (Bar graph Screen)
This screen indicates the water level in a bar graph mode. In the example below, the water level, in way of the five holds, is in zero position (no water) and the fore peak tank is at the level of 14.67 m. sounding.
In the View Menu, various buttons are listed. Each bar per hold reflects the data transmitted from the corresponding sensor, which is located on the centreline of each hold, up to 30 mm (recommended) above the level of the tank top. Over the bar, the number of the corresponding hold is indicated. The Blue colour numbers, located under each bar, indicate the actual water level, in cm. The Green colour numbers show the High level alarm set up point and the Cyan coloured numbers below them indicate the Low level alarm set up point.
In the example screen above, The level bar of No 5 hold is located at 0.13 m. this indication is below the Low Level limit. Accordingly, no relevant alarm is activated, at present.
In the top right area of the screen, the forecastle level indicator flashes, indicates that the water level in forecastle area is more than 20 cm above the deck level. At this time, once the officer touches the screen button “open”, the remote drain valve or the relevant drain pump activate.
At the end of the operation the drain valve switch should be correctly closed by touching the “Close” button. If the operation is forgotten, alarm will be triggered to indicate that this valve has not been correctly closed. A text trailer to this effect will also move on the screen top.
3. Water Ballast Level indication
It is very useful for the officers to be aware of the exact quantity of ballast water in ballast holds during a ballast voyage and to be able to set an alarm to indicate, when the water level is dangerously low, for any reason. This mode will further protect the ship’s stability against excessive free surface effect and will avoid ship’s sides and bulkheads being damaged by sloshing.
In this example screen opposite, the water level in way of hold No 3 has already been dangerously reduced. Consequently, the alarm is activated, the frame and the level numbers flash and the movable text trailer appears. At this screen the forecastle space is dry, because the button, which is connected to the corresponding sensor, is green coloured. Additionally, the bar graph, related to the fore peak tank, shows that this tank is slack.
This alarm is not automatically transferred to the VDR unless specifically required by the owner.
4. Alarm Settings Screen
This screen shown opposite is used to set up the low and high level alarm for each hold sensor. These settings are considered as default settings. They are defined by IMO rules. That is why, only the makers can interfere with them.
Master and officers may set up various other alarms(by code), if they want to monitor other parameters i.e. forepeak ballast tank level, ballast holds level, or max draught(s), trim etc.
All the alarm settings comes automatically to factory settings with simple switch off and on the system.
5. Draughts Alarm Screen
The opposite screen is the Draughts Alarm screen. Level bar graphs indicate the vessel’s draughts (forward at mid ship port and starboard and aft.), assisting the crew to monitor them, during a voyage. Officers may set up alarm(s), when they navigate in draught restricted areas.
Details of Sensor’s Container for each hold
FOR MORE DETAILS PLEASE CONTACT :
A) P L P AUTOMATION LTD. GERASSIMOS PRONOITIS
26, BOTSARI STR.
185 38 PIRAEUS
TEL. 210 4284023
FAX. 210 4534188
Email : firstname.lastname@example.org
B) P&C INTERNATIONAL CONSULTANCY MARINE SERVICES LTD.
143, KOLOKOTRONI STR.
185 36 PIRAEUS
TEL. 210 4515526
FAX. 210 4599349