Hamburg based Manufacturer Lemag, Lehmann & Michels has indigenously designed a system that is approved by MAN Diesel & Turbo. This system allows safe changeover from heavy fuel oil (HFO) to marine distillate oil (MDO) and vice versa.
The system can be operated either from the engine control room, or directly. The design includes a DIESEL switch changeover valve, sealed with magnetic coupling, with a feedback sensor over the rotor position. Three special valve designs also enable changeover when the HFO and MDO tanks have different tank levels. A difference of 20m in tank level can be accommodated. In total more than 50 alarm systems control the process and protect the engine.
The best part of the system is supply of dosage and blending equipment for fuel additives, which can be automatically switched during the changeover process to prevent incompatible fuels from flocking. A system to enhance lubrication dosage during MDO operation is also available.
Few other lucrative features which include the backup storage of the time – and, as an option, the GPS position – at which changeovers were made. The data is stored on a data logger that cannot be manipulated, but is available for port state control to read. Data is logged at the beginning of the changeover, when the HFO valve is closed and when flushing is theoretically completed
The system is available in several variations, from a low-budget standard version to a system with full control of the fuel consumption, using Coriolis flow meters to measure the amount of HFO and MDO coming from the service tanks.
Source: Motorship
A small sketch of the lines would have very helpfull for the circuit to be fully understood.