MEO CLASS4 ORAL 25/03/2021

 

MEO CLASS4  25/03/2021

QUESTIONS AND ANSWERS

1. Crank case explosion
2. Main engine one unit exhaust temperature is increased ,what PARAMETERS will you Check,what will be ur action, what can be the reason?
3. BOILER MOUNTINGS
4. AIR IN THE REFER COMPRESSOR,HOW WILL YOU FIND AND WHAT WILL BE THE ACTION.
5. MAIN BEARING AND BOTTOM END BEARING CLEARANCE

CRANK CASE EXPLOSION

HOW IT WILL HAPPEN?

• TO MUCH CLEARANCE BETWEEN BEARINGS,
• OIL FLIMS MAY BREAKDOWN 
• DIAPHRAGM IS NOT SEALING PROPELY
• PISTON CROWN IS BROKEN, EXHAUST GAS MAY LEAK TO CRANK CASE,
• CIRCULATING LUBRICATION OIL NOT PROPER.
• ENGINE CHAIN DRIVE IS TOO TIGHT. WHICH MAY LEADS TO HOT SPOT.
• GEARS DONT HAVE PROPER LUBRICATION.

PRIMARY EXPLOSION?

• DUE TO ANY ABOVE REASON HOT SPOT WILL CREATE. WHEN LUBRICATION OIL CONTACT WITH HOTSPOT  OIL BECOMES VAPOUR, AGAIN VAPOUR WILL COME AND  CONTACT WITH THE HOTSPOT, PRIMARY EXPLOSION WILL HAPPENED.

SECONDARY EXPLOSION?

• AFTER THE PRIMARY EXPLOSION, PRESSURE WILL INCREASED INSIDE THE CRANKCASE.
• NOW CRANKCASE RELIEF VALVE WILL ACTIVATED RELEASE ALL PRESSURE .
• AFTER THIS CRANK CASE BECOME VACCUM AGAIN. NOW IF FRESH AIR WILL COME INSIDE THE CRANKCASE SECONDARY EXPLOSION WILL TAKE PLACE.

TO AVOID THE SECONDARY EXPLOSION

• ALL MAIN BEARINGS AND TRUST BEARINGS HAVE TEMPERATURE SENSORS. IT WILL GIVE ALARM ONCE TEMPERATURE INCREASED. 
• IN NEW TYPE OF ENGINES WE HAVE A SENSOR OF WEAR DOWN OF MAIN BEARINGS. (IF UNEQUAL WEAR DOWN MEANS OIL FLIMS WILL BREAKDOWN.)
• AND WE HAVE NON RETURN VALVE TYPE RELIEF VALVE WHICH WILL RELEASE ALL PRESSURE WHEN PRIMARY EXPLOSION TAKE PLACE INSIDE THE CRANK CASE.

MAIN ENGINE ONE UNIT  EXHAUST TEMPERATURE IS INCREASED- WHAT PARAMETERS YOU WILL CHECK,WHAT WILL BE YOUR ACTION AND WHAT CAN BE THE REASON?

REASON FOR ONE UNIT EXHAUST TEMPERATURE INCREASED?

• THERMOMETER FAULT
• BLOW PAST 
• SCAVENGE FIRE
• EXHAUST VALVE LEAKING
• FUEL PUMP MALFUNCTION
• FUEL INJECTOR FAULT
• LESS AIR IN FUEL 
• TAPPET CLEARANCE IS MORE.

WHAT ARE THE PARAMETERS SHOULD CHECK IF ONE UNIT EXHAUST TEMPERATURE IS INCREASED?

• THERMOMETER SHOULD CHECK IF IT'S WORKING PROPELY OR NOT.
• SCAVENGING MANIFOLD TEMPERATURE SHOULD CHECK 
• SHOULD CHECK TAPPET CLEARANCE 

ACTION WHEN INCREASED EXHAUST TEMPERATURE IN SINGLE UNIT.

• REDUCE ENGINE RPM 
• INCREASE CYLINDER LUBRICATION
• TAPPET CLEARANCE CHANGE 
• OVERHAULING FUEL PUMP 
• OVERHAULING FUEL INJECTOR
• ADJUST FUEL INJECTOR TIMING
• SENSORS CHECK OR CHANGEOVER

BOILER MOUNTINGS

 

• OGEE RINGS
• DEMISTER
• RING AND DISTRIBUTER
• FUSIBLE PLUG
• PRESSURE GAUGE
• STEAM STOP VALVE 
• AUXILIARY STEAM STOP VALVE 
• BOTTOM BLOW DOWN VALVE 
• SCUM BLOW DOWN VALVE 
• SAFETY VALVE 
• SALINOMETER VALVE 
• FEED CHECKER VALVE 
• GAUGE GLASS
• VENT

 

REFER AIR IN THE SYSTEM, HOW WILL YOU FIND AND WHAT WILL BE THE ACTION.

AIR IN THE REFER SYSTEM HOW WILL YOU FIND?

• ABNORMAL HIGH DISCHARGE PRESSURE
• JERKING OF COMPOUND PRESSURE GAUGE
• VERY SMALL BUBBLES IN SIGHT GLASS
• CONDENSER TEMPERATURE HIGH.

ACTION IF AIR IN THE REFER SYSTEM?

• CHANGE THE COMPRESSOR TO MANUAL MODE 
• BYPASS THE LOW PRESSURE CUT OUT 
• CLOSE THE LIQUID STOP VALVE AFTER THE CONDENSER.
• PUMPING ENTIRE  REFRIGERATION INTO CONDENSER.
• UNTIL SUCTION PRESSURE IS BECOME ZERO.
• STOP THE COMPRESSOR AND CLOSE THE CONDENSER SUCTION VALVE 
• THEN GIVE SOME TIME TO COOL DOWN
• THEN OPEN THE PURGE VALVE ON THE CONDENSER.
• AIR WILL GO OUT. WAIT FOR REFRIGERANT COME OUT.
• THEN CLOSE THE PURGE VALVE .
• OPEN THE LIQUID STOP VALVE AND COMPRESSOR SUCTION VALVE START THE COMPRESSOR. 
• CHECK THE SIGHT GLASS.

MAIN BEARING AND BOTTOM END BEARING CLEARANCE?

MAIN BEARING (JOURNAL BEARING) CLEARANCE?

• CLEARANCE MEASURES JOURNAL BEARING TO UPPER SHELL USING TELESCOPIC FEELER GAUGE

BOTTOM END BEARING (CRANK PIN)

PISTON - BDC 

• CLEARANCE BETWEEN BOTTOM END BEARING TO BOTTOM SHELL USING FEELER GAUGE.