Marine fuels testing company VPS on Thursday (1 October) examined the connection between Safety of Life at Sea (SOLAS) readiness and why correct fuel selection, regular condition monitoring and lubricating oil analysis are essential for lifeboats, emergency generators, fire pumps and other safety-critical equipment.
Neil Chapman, Managing Director of the Americas; Stanley George, VPS Group Science & Technical Manager; and Steve Bee, Group Marketing & Strategic Projects Director, discussed the topic:
In an emergency at sea, there is no second chance. If a lifeboat engine fails to start, an emergency generator cannot take load, or a diesel driven fire pump loses power, the consequences can be immediate and serious. Fuel is only one part of emergency equipment reliability but it is essential and can remain largely unseen as the equipment sits on standby for prolonged periods. Careful selection of this fuel can minimise the risks of failure when it is needed most.
Executive Summary
Safety of Life at Sea (SOLAS) regulations, require emergency equipment to be immediately available and capable of performing its intended safety function. The fuel carried within this key safety equipment must be suitable and maintained in a condition that ensures reliable operation of lifeboats, emergency generators and other emergency assets when called upon. To support SOLAS regulations and requirements, there is within ISO8217, a special-purpose distillate grade fuel, ISO-F-DMX, specification, specifically intended for use in emergency equipment. With DMX-grade fuel, ISO8217 has specified a set of parameters and test scope. The properties of this fuel are designed to ensure rapid ignition after long idle periods, low-temperature operability, long-term storage stability and absence of biodiesel-related degradation risks. Accordingly, these properties include a relatively high minimum cetane index, defined low temperature performance and the requirement that the fuel is free of FAME. In normal marine operations, DMX is suitable for the diesel engines fitted to lifeboats, rescue boats, emergency generators, diesel driven emergency fire pumps and, where fitted, diesel driven emergency compressors.
However, in practice, emergency equipment tanks are not always filled with DMX. VPS has noted that, in a significant number of cases, fuels other than DMX are used in emergency equipment tanks, including DMA, DMB, unspecified marine diesel and automotive diesel. These products should not automatically be regarded as equivalent to DMX, as their FAME content, ignition quality and cold flow characteristics can differ. The condition of the fuel can also change when it remains in storage for extended periods.
A recent VPS review of emergency equipment fuel samples found that 48% were not identified as DMX, 28.6% contained FAME above the 0.1% level, and 6.2% showed microbial contamination. These figures are not equipment failure rates, but they show that fuel selection and the condition of the stored fuel deserve greater attention as part of routine emergency equipment assurance. As such, the use of DMX is less about fuel economics and more about reliability of safety-critical equipment when lives are at risk.
Why DMX Grade Matters
ISO 8217:2024 specifies DMX with a kinematic viscosity at 40°C of 1.400 to 5.500 mm²/s, a minimum cetane index of 45.0, a maximum cloud point of -16°C and a minimum flash point of 43°C. The standard also states that DMX shall be free of FAME. Unlike DMA and some other distillate grades, no density limit is specified for DMX.
The cetane index requirement is relevant to ignition quality. The minimum cetane index for DMX is 45.0, compared with 40.0 for DMA and DMZ and 35.0 for DMB. This is useful for equipment expected to start promptly after remaining idle for long periods.
Cold flow performance is equally important. For DMX, the maximum cloud point is -16°C. At or below the cloud point, wax crystals begin to form and may eventually restrict small bore fuel lines and filters. Fuel used in emergency equipment should therefore remain suitable for the lowest ambient temperature in which the equipment may be required to operate.
ISO 8217:2024 requires DMX, DMA, DFA, DMZ and DFZ fuels to appear clear and bright. If the fuel is dyed and not transparent, preventing this visual assessment, water shall not exceed 200 mg/kg when determined in accordance with ISO 12937.
The requirement for DMX to be free of FAME is also relevant to storage. FAME has a greater affinity for water than conventional hydrocarbon distillate fuel and can influence oxidation stability and storage behaviour. Where water is present, microbial growth can develop at the fuel/water interface, with the potential for sludge formation, deposits and filter blockage.
Key Fuel Related Risks in Emergency Equipment
The concern is not limited to whether an engine can run on a particular fuel. Emergency equipment may remain on standby for long periods and then be expected to start promptly and sustain the required duty. The main fuel related pathways are summarised below.
Lifeboat Fuel Capacity
SOLAS Chapter III, Regulation 31.1.4 (Survival Craft Motor Requirements) states: “Sufficient fuel, suitable for use throughout the temperature range expected in the area in which the ship operates, shall” be provided to run the fully loaded lifeboat at 6 knots for a period of not less than 24 hours. This requirement is important as it is here that SOLAS explicitly refers to fuel quality, requiring the fuel to be suitable for the environmental conditions in which the vessel operates.
Note: The full article by VPS can be found here.
Photo credit: VPS
Published: 2 October, 2026
