MAN B&W engines have various proven methods of isolating fuel for a particular unit. Of all the methods, two are very prominent and essential for every watch keeping engineer to know. The Engineer in charge of the watch should decide one of the two methods depending whether the engine is in STOP condition or FULL AWAY at sea. The method described below (check with the engine manufacturer’s manual for individual engine valve number and location) can be adopted when the engine is FULL AWAY at sea.
The steps are:
1. Operating the Puncture Valve
2. Lift the Fuel Pump Roller
3. Shut Fuel Oil Inlet Valve (Only for Maintenance purpose – Not During Running).
Manual actuation of Fuel Pump Lifting Device (148) activates Cylinder 149, which lifts & locks the Fuel Pump Roller, so that there is a gap (approx. 2 mm) between the roller and cam – see picture for details
Here is a clear picture of the Cut-off Cylinder 149 – you can see how it turns the shaft, to lift the Roller. In older engine models, this was done manually by turning the shaft (with a special tool), but on the newer MC engines, the pneumatically operated Cylinder (149) does the job even when the engine is running.
Cylinder 149 is located very near the reversing Cylinder 13 (which shifts the Fuel Pump Roller during Reversing) – Cylinder 13 can be seen on the side of the Fuel Pump block.
Have you encountered any such situation where you have to isolate fuel to a particular unit or any other interesting method – do share with us.