A Guide to Ballast Tank Gas Detection 

The danger of cargo leaks into ballast tanks and the explosive risk associated with a build up of hydrocarbon gas is well known. The deployment of continuous ballast/void space tank gas detection systems on vessels has become a general requirement for leading chartering companies and the vast majority of new tankers are now fitted with gas sampling systems.

Traditionally ballast tank gas sampling systems drew samples from sampling points in the bottom of the ballast tanks. However, this method has several inherent problems such as the difficulty of maintenance and if there is any remaining ballast water or mud in the bottom of the tank, your sampling point can become blocked and you have no monitoring in that tank. Martek advocate the positioning of sample points just below the tank top. Due to the speed that gas dissipates/diffuses around an enclosed space the detection system will pick up concentrations of even the heaviest hydrocarbons.

Recently new tanker specifications have moved towards two sampling points per tank (one near the tank top and one near the bottom of the ballast tank). These specifications now also call for ballast gas detection systems to provide detection of low oxygen content and hydrogen sulphide concentrations within the ballast tanks.

Exxon Mobil issue their MESC (Minimum Environmental and Safety Criteria) which sets down the systems that must be fitted on any tankers they charter. The latest copy of these requirements stipulates that ballast tank gas sampling must be fitted.

The MM5001® - Ballast Tank & Void Space Gas Sampling System

The MM5001® system is a Type Approved (Lloyd's Register) gas sampling system for ballast tanks, void spaces and cargo pump rooms, developed to meet the requirements of the industry.

The MM5001® sequentially draws air samples from each ballast tank and analyses them for hydrocarbon gas and other gases such as hydrogen sulphide and oxygen if required. If a gas concentration above the pre-set alarm threshold is detected, an audio-visual alarm will immediately alert the operator of the problem.

New advances in the central PLC controller means the entire MM5001® system can be monitored and the alarm status be shown through user-friendly touchscreen panels. This allows users to see information, navigate through the set up procedure and programme different aspects of the system to meet their requirements.

The system is also fully compliant with the IACS Unified Requirement UR F43 the outline specification of ballast tank gas sampling systems.

The system is available with a unique infra-red hydrocarbon gas analyser which requires no recalibration in service. This provides a major advantage to operators over conventional systems, which can require annual attendance by the manufacturers' service engineer.

Click here for more information about the MM5001® Ballast Tank & Void Space Gas Detection System.