- ENSURE THAT THE HEAVY FUEL OIL IN SERVICE TANK IS IN NORMAL TEMPERATURE.
- REDUCE THE ENGINE LOAD TO 25-40% MCR.
- OPEN THE STEAM TO THE PREHEATERS.
- MANUALLY OPERATE THE VISCOTHERM TO RAISE THE TEMPERATURE OF MDO TO 60- 80 °C MAXIMUM. THE TEMPERATURE RAISE SHOULD BE SLOW BUT CONSISTENT. THE VISCOSITY OF DIESEL OIL AT NO POINT SHOULD BE MADE LESS THAN 3 CST OR IT WILL LEAD TO FUEL PUMP AND FUEL VALVE SCUFFING, LEADING TO RISK OF STICKING DUE TO FALL OF LUBRICATION ABILITY OF DIESEL OIL.
- NOW SLOWLY OPEN THE HFO BY OPERATING THE CHANGE OVER VALVE. THE TEMPERATURE IS MADE TO RISE STEADILY AND VISCOTHERM IS SET FOR 10-15 CST. 20 CST IS ALSO OK AS BEFORE FUEL PUMP VISCOSITY IS NOT A STRICT CRITERION.
NOTE :- THE TEMPERATURE OF HFO AT THE TIME OF CHANGEOVER SHOULD NOT BE MORE THAN 25°C MORE THAN MDO AS IT WILL LEAD TO SCUFFING SAME AS BEFORE.