ALL ABOUT WIDAS – WATER INGRESS DETECTION & ALARM SYSTEM

Bulk carriers must be fitted with an approved water ingress detection system to comply with the SOLAS XII Regulation 12 regardless of their date of construction not later than the date of the annual, intermediate or renewal survey, whichever comes first, to be carried out after 1st July 2004.

The system is for the early detection of any leakage into all cargo holds, ballast tanks, forward of the collision bulkhead (ex. F.P.T), and dry spaces (ex. bosun store) which extends forward of the foremost cargo hold.

SOLAS XII REGULATION (FOR CARGO HOLD, BALLAST & DRY SPACES)

1. Bulk carriers shall be fitted with water level detectors

• In each cargo hold, giving audible and visual alarms, one when the water level above the inner bottom in any hold reaches a height of 0.5m and another at a height not less than 15% of the depth of the cargo hold but not more than 2m. On bulk carriers to which regulation 9.2 applies, detectors with only the latter alarm need be installed. The water level detectors shall be fitted in the aft end of the cargo holds. For cargo holds which are used for water ballast, an alarm overriding device may be installed. The visual alarms shall clearly discriminate between the two different water levels detected in each hold.
• In any ballast tank forward of the collision bulkhead required by regulation II-1/12, giving an audible and visual alarm when the liquid in the tank reaches a level not exceeding 10% of the tank capacity. An alarm overriding device may be installed to be activated when the tank is in use and
• In any dry or void space other than a chain cable locker, any part of which extends forward of the foremost cargo hold, giving an audible and visual alarm at a water level of 0.1m above the deck. Such alarms need not be provided in enclosed spaces the volume of which does not exceed 0.1% of the ship maximum displacement volume.

2. The audible and visual alarms specified in paragraph 1 shall be located on the navigation bridge.

3. Bulk carriers constructed before 1 July 2004 shall comply with the requirements of this regulation not later than the date of the annual, intermediate or renewal survey of the ship to be carried out after 1 July 2004, whichever comes first.

WIDAS OVERVIEW

The WIDAS (Water Ingress Detection & Alarm System) is a simple system that consists of a Water detector, I.S barrier box for intrinsically safety and Main alarm panel for visual & audible alarm, etc. The sensor and the alarm panel are connected together with an intrinsically safe barrier.

Each component is designed and approved especially for marine circumstance endurance and convenient operation.

OPERATING PRINCIPLE

This system consists of the Main alarm panel/Repeat alarm panel (Optional) on which the audible and visual alarms are activated and Electrode Type Level Switch operated by detecting the conductivity in the liquid. When the presence of water has reached the detecting point of the level switch installed on the preset detection level in the cargo hold or other space, the electric signals which are activated on the level switches are transmitted to the main alarm panel provided with alarm unit, power supply unit and alarm buzzer, malfunction alarm as well as overriding device. At the same time, the audible and visual alarms are activated on the main alarm panel installed on the Navigation Bridge and the repeat alarm panel installed on the bridge. The overriding device for which the alarm can be deactivated or reactivated for the detector installed in the tank and holds used barrier carriage of water ballast will be provided on the alarm panel according to the SOLAS regulation XII/ 12.1. An override visual General Information & Application should be continuously provided throughout deactivation of the water level detector for the hold or tanks used for the carriage of water ballast. Where such an override function is provided, the override condition should be automatically reactivated after the hold or tank has been a level below the lowest level alarm indicator level. When the fault is detected on a water level detector, The Malfunction Alarm having visual and audible alarm the same as detection alarm on the main alarm panel should be activated to monitor continuously the system. The audible alarm should be capable of being muted but the visual indication should remain active until the malfunction is cleared. The Main power and Standby power should be prepared on this system and if the main power is failed, the standby power should be supplied to the main alarm panel so as to monitor continuously. When the main power is failed, the power failure alarm having audible and visual alarm should be operated. The water ingress detection system should be continuously operated while the ship is at sea. The Electrode Type Level Switch installed in appointed space should be satisfied with the intrinsically safe type with the I.S barrier. These level switches should be installed either in the aft part of each cargo hold or in the lowest part of the spaces other than cargo holds to which these requirements apply. Level Switch or Sensors can be float type, Water sensor type, Reed Type, Capacitance type.

For CARGO HOLD:
1) An alarm, both visual and audible for which the space is identified on the main alarm panel will be activated when the depth of water at the level sensor reaches the pre-alarm in the space being monitored.

2) An alarm, both visual and audible on the main alarm panel will be activated when the level of water at the sensor reaches the main alarm level, indicating increasing water level in a cargo hold. In addition, the both alarms will identify the space and the audible alarm should not be the same as that for the pre-alarm level.

For COMPARTMENTS OTHER THAN CARGO HOLDS:
1) An alarm, both visual and audible, indicating the presence of water in a compartment other than a cargo hold on the main alarm panel will be activated when the level of water in the space being monitored reaches the sensor. The visual and audible characteristics of the alarm indication will be the same as those for the main alarm level in a hold space.

Moreover, it has the Malfunction monitoring function for power failure, line break & shorted circuit.

REFERENCES

• PSM MARINE www.psmmarine.com/
• HONEYWELL www.honeywellprocess.com/
• HANLA IMS www.hanlaims.com/

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