JUNE 7, 2013 — MAN PrimeServ – MAN Diesel & Turbo's service division – recently retrofitted its 20,000th slide fuel-valve. Introduced at the turn of the millennium, slide fuel-valves improve the low-load operating capability of engines. Standard on all new MAN B&W engines, they can also be retrofitted on MC engines.

The slide fuel-valve eliminates the so-called "sac volume" which reduces fuel-oil consumption and also eliminates dripping from the fuel-valve nozzle.

Compared to conventional valves, the slide fuel-valve has NOx-reduction potential. The reduced sac volume leads to an improved combustion process, resulting in fewer deposits throughout the gas ways and a reduction in overall emissions, such as HC, NOx and particulate matter. Visible smoke conditions are also greatly reduced as a result of the improved combustion.

Engines with slide fuel-valves have, due to improved low-load performance with regard to soot formation, a significant advantage in an era where "slow steaming" (sailing at part load) has become the industry norm. This reduces/eliminates the need to run at high revolutions in order to clean exhaust channels.

The procedure for replacing standard valves with slide fuel-valves is straightforward and can be carried out by ship personnel after instruction or MAN PrimeServ as required.

• Fitting the new valve type brings many benefits to the table, including:
• Improved low-load performance
• Better combustion process
• Reduced fouling of gas ways and exhaust-gas boiler
• Reduced fouling of piston top land
• No drips – no sac volume
• Less visible smoke formation
• Lower HC, NOx and particulate matter emission levels

Hydrocarbon consumption versus load for conventional and slide fuel-valves

Christian Ludwig – Head of Retrofit & Upgrade – MAN Diesel & Turbo, said: "Slide fuel-valves have proved to be very popular within the marine, two-stroke market. Really, it's a case of having introduced the right technology at the right time and the slide fuel-valve's strong market performance is testimony to the fuel savings and increased environmental profile it brings to working vessels. It is important to note that slide fuel-valves improve the low-load operating capability of engines."