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The shipping industry must be sustainable. Since 2020, an upper limit of 0.5% has been in place for the sulphur content in ship fuels. As the cleanest fossil fuel, LNG can comply with this limit. It is therefore no surprise that it is the fastest-growing segment in the shipping fuel sector.

This future-ready alternative requires the installation of a suitable cryogenic fuel tank, as well as a system to convey the fuel to the engines. This FGSS (fuel gas supply system) comprises evaporators, compressors, pumps and a central automation system. In the explosion-protected sector, intrinsically safe remote I/O systems, such as IS1+, monitor all processes. What's more, they transmit diagnostics signals, which enable proactive maintenance to be performed. The compact IS1+ system is particularly suitable for tight spaces on ships. As well as international Ex certifications, it has also been granted a number of ship approvals, including DNV-GL, ABS and ClassNK. Robust Ex e stainless steel enclosures guarantee a long lifetime. For harsh environments at sea, the range also includes explosion-protected, rugged operating stations.

Double-walled, cylindrical cryogenic tanks are used to store LNG. Here, LNG is kept under a constant pressure; the inner tank is designed as a pressurised container. Despite this, a certain amount will evaporate, which causes the internal pressure inside the tank to increase. However, suitable pressure limiting equipment, particularly safety valves are used to avoid critical internal pressures. This results in the formation of "boil-off gas" (BOG), which can be re-liquefied and returned. BOG compressors, which can be controlled using explosion-protected remote I/O stations such as IS1+, are used for this purpose. Tank shut-off valves and recirculation valves, flow regulation systems, and tank pumps for draining are key elements of the storage units in combination with control systems of this kind. In addition, LNG storage tanks are equipped with ATEX-certified pressure, temperature and fill level sensors. The values from this measuring equipment can also be recorded using remote I/O systems.

Alongside storage tanks, filling hoses or permanently installed loading arms are also installed at LNG filling stations. The filling process for trucks that are powered by LNG is performed using pumps or using the differential pressure between the storage tank and fuel tank. During the filling process, the cryogenic LNG is brought to the saturation pressure in the fuel tank (6–10 bar) using a heat exchanger.

One thing that cannot be overlooked here is electrostatic grounding. A combination of a grounding clamp, cable and monitoring device does more than just prevent explosions when filling LNG. Grounding monitoring devices from the 8485 and 8146 series also continuously monitor the state of the grounding. They can be selected depending on the ambient temperature and required degree of protection for Zone 1 or Zone 2.

In addition, explosion-protected operating panels and control units for monitoring the temperature and pressure, as well as for controlling the pumps, are key elements of the safety concept for LNG filling stations.

Further safety equipment includes gas warning devices for detecting leaks and devices for potential equalisation. These are complemented by signalling devices, alarm devices and camera monitoring. In this area, too, R. STAHL offers a wide, explosion-protected range of linear luminaires, tubular light fittings, floodlights, emergency luminaires, monitoring cameras and even thermal cameras, which can detect leaks.