MetriGuard – Water Ingress Alarm

• Satisfies SOLAS Chapter XII, Regulation 12 for Bulk Carriers
• Optional direct connection to VDR
• Optional level indicatior for ballast and floodable holds

JOWA USA's MetriGuard Water Ingress Alarm System is intended for usage on bulk carriers. It complies with the proposed SOLAS regulations (Chapter XII, Regulation 12) requiring water level alarms in cargo holds and certain other spaces.

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​The major elements of the MetriGuard Water Ingress Alarm System are:

1. Metritape resistance-tape sensor and sensor housing
2. Float switch and junction box
3. Signal Conditioning Unit with intrinsic safety barriers
4. Alarm unit

Figure 1 shows a block diagram of a typical system. The primary sensor used in the cargo holds and ballast tanks is the Metritape type LA series water sensor. This continuous sensor allows two alarm setpoints to be derived from one sensor. The sensor mounts in a customer stillpipe which protects the sensor from the cargo. A sensor housing bolts to a pipe flange on top end of the stillpipe allowing the sensor to be easily installed (or removed) from the deck. In addition, all electrical connections are made in the sensor housing.

In other spaces where there is never any cargo or ballast, a simple float switch that does not need a high degree of physical protection may be supplied. The float switch cable must be terminated in a small junction box suitable for the deck cable.

All deck cables will be brought to a Signal Conditioning Unit that will contain any required intrinsic safety barriers. This enclosure must be mounted in a non-hazardous protected area but it does not have to be mounted on the bridge or in any area that requires frequent access.

Figure 2 shows the layout of a typical water ingress alarm unit. The alarm unit has all indicators, switches, relays and power supplies. It will accommodate a maximum of 16 total spaces (cargo holds, forward ballast tanks and other spaces) and will provide two high level alarms per space. The front panel has a common buzzer, an acknowledge (buzzer silence) switch and a test switch. Associated with each space will be three light emitting diode (LED) indicators: High Level Alarm (HLA), High-High Level Alarm (HHLA) and Override. Three switches are provided to enable or disable (Override) any alarms in each space (that may be used to carry ballast) when that space is carrying ballast.

The resistance-tape sensor may be operated in hazardous classified areas when used with approved intrinsic safety barriers. In addition, the sensor can easily be installed in stillpipes that have slight curves and slopes but some restrictions apply.

A sensor or cable open circuit will cause a fault indication - both HLA and HHLA LED's will flash. When acknowledged, only the HHLA LED will illuminate. Any sensor or cable short circuit will actuate both alarms.

Key Features

• Two high level alarms one fixed at 0.5 meters, the other adjustable between 0.5 to 2.5 meters
• Alarms can be disabled with 'Override' switch. Indicator shows that the cargo hold or tank is in 'override' mode
• Used with holds and tanks up to 35 meters high
• Sensor fault will also set off alarm
• Common buzzer, acknowledge (buzzer silence) switch and test switch
• Provision for operation from backup (secondary) power source; includes automatic switchover
• Provides standard common relay outputs for HLA and HHLA alarms and Fault / Loss-of-Power

Metritape – Tank Gauging

• Resistance-tape technology
• Full height and Independent High Alarm combined within a single deck penetration
• Integral temperature detector options
• Flexible sensor for J-Shaped Ballast tanks

Sentry IV – Tank Gauging System

• Cost competitive, computer-based solution to monitor cargo, ballast, draft and service tank levels
• Digital, tabular and analog bar graphs for presentation of tank levels
• Optional inert gas pressure measurement

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In response to the industry trend of integrating onboard instrumentation with a streamlined approach to system gauging, JOWA USA provides a family of Metritape tank level gauging systems including: Vanguard IV, Sentry IV, DeckMaster IV, Metricircuit 60,000 Metrimeter, and Metriguard Tank Monitor. Utilizing our Metritape technology, the systems are cost-effective, reliable, low-maintenance and stable. All systems offer computer-based centralized control and monitoring. Independent high alarm can be achieved by installing two resistance-tape sensors in a single deck penetration. These systems can also include temperature detection and IG/tank pressure monitoring.