PREPARATION
- Bridge informed so that the engine rpm is not varied.
- Engine must be run at constant rated load for atleast an hour.
- The flowmeter reading must be taken before and after the hour.
- Ship must be fully laden and propeller fully immersed.
- Ship sailing in calm weather, neither against the wind or along with the wind.
- Indicator instrument has to be checked Sarah free functioning the Piston has to be removed and Asin that it is a freely moving and the lubricated properly. the indicator drum has to rotate freely, the indicator record has to be of sufficient link so that vibrations are not induced, vindicated Ram has to be positioned such that the diagram comes exactly in the middle of the paper comma the stylus has to be properly pressed.
- The indicator cock has to be blown to remove any deposits before attaching the equipment.
- Indicator cam timing has to be checked by taking a compression diagram with fuel cut off and at low RPM.
- Proper spring rating has to be taken from chief engineer.
- Atmospheric line has to be drawn with the indicator equipment connected and valve closed. This also ensures that the equipment is at the same temperature of the engine.
TYPES OF CARDS
1. COMPRESSION CARD - this has to be taken with the indicated Ram rotation is in face with the piston of the engine. The engine should run at low RPM and fuel cut off. It gives an indication of the compression pressure and the indicator cam timing.
1. COMPRESSION CARD - this has to be taken with the indicated Ram rotation is in face with the piston of the engine. The engine should run at low RPM and fuel cut off. It gives an indication of the compression pressure and the indicator cam timing.
2. POWER CARD OR IN PHASE DIAGRAM - it is taken with the indicated drum
rotation in phase with Piston movement. It means that when the piston is
it TDC and BDC the indicator equipment Piston will also stop, and it
will be maximum when the piston of the engine is in the middle.
The area within this diagram represents the work done during the cycle. The length of the diagram represents the volume of the cylinder and the height of the diagram represents the maximum pressure from the atmospheric line. Mean effective height of the diagram is represented by dividing the area with the horizontal length. We get the mean effective pressure by multiplying the spring constant with this mean effective height.
The area within this diagram represents the work done during the cycle. The length of the diagram represents the volume of the cylinder and the height of the diagram represents the maximum pressure from the atmospheric line. Mean effective height of the diagram is represented by dividing the area with the horizontal length. We get the mean effective pressure by multiplying the spring constant with this mean effective height.
Mean effective pressure = (area of the curve/length of the curve)×spring constant
Work done = Pm*Volume= Pm×A×V
Power = Pm×LAn
where n= no of power strokes (N for 2stroke and N/2 for 4stroke, N=rpm)
L= length of the stroke
A= area of piston
Pm=Mean Effective Pressure
AS PER MANUAL
3. DRAW CARD OR OUT OF PHASE DIAGRAM
Power career power cord has set and limitations that it is only used to calculate power and mean effective pressure. Since it depends on Piston movement, volume changes are very small and on either side of TDC and bdc. So it can not represent what is happening in compression and start of combustion.
If the drum is made out of phase by 90 degrees with the Piston movement, then the drum will be moving fast as the Piston comes over to TDC and bdc. This clearly illustrates the pressure changes during fuel combustion that is injection and ignition.
4. LIGHT SPRING DIAGRAM
This is again similar to the power cord and in face with the engine, but taken with the light compression spring of about 10 bar. This enables to examine what is happening around bdc that is 1 exhaust valve opens and scavenging of a takes place. Ask eastern comes up on compression, the spring will be fully compressed against the limiting stop at about 10 bar. Compression line will then stay horizontal has compression pressure increases and when expansion takes place. As the exhaust valve opens and the pressure drops below 10 by then the curve will fall and rises when scavenge opens.
IRREGULARITIES IN DIAGRAMS
1. EARLY IGNITION can be found out with power cord and draw card.
Causes - incorrect fuel pump timing comma incorrect VIT timing comma broken broken or wrong reset injector springs, incorrect fuel condition or overheating of parts within the cylinder.
Effect - this causes an abnormally high peak pressure in the cylinder at about the top of the Piston stroke due to which a heavy shock load will be transmitted to the running gear and bearings with a corresponding knocking sound. Although thermal efficiency is high and exhaust exhaust temperatures are reduced, the shock load and consequent vibrations may cause damage to the engine.
2. LATE IGNITION
Causes - it may be due to poor atomization high viscosity or poor quality fuel, fuel pump leaking or incorrectly time, low compression, insufficient supply of combustion air, or undercooling of parts within the cylinder, excessive injector spring setting.
Effects- this causes a low key pressure which occurs when after top centre of the Piston. Power is lost since the fuel is not burnt correctly to transmit power at the most effective part of the stroke. Combustion may continue during the expansion stroke and may be incomplete giving lost in energy produced, Hai exhaust temperature and smoke.
4. AFTERBURNING
This refers to slow on 8 combustion of fuel during the expansion stroke of the Piston and is shown by a rise in the expansion line during the later part of the stroke that is expansion stroke. Exhaust temperature and pressure will be hi, with burning Civil and carbon passing to exhaust. This may Ban exhaust valves and founder II exhaust system comma with risk of turbocharger surging uptake fires. High temperatures within the cylinder cause a deterioration in lubrication and possible damage to liner surface and Piston rings. This may also be burning of the Piston crown.
5. LEAKY FUEL INJECTOR
This can be detected by Hai exhaust temperature and smoke it exhaust, loss in power. As the fuel pump has to compensate the space left by licking fuel injector a sudden search in the fuel pressure wave will be occurring in the fuel line which will cause the knock. An indicator diagram taken from the cylinder will show fluctuations of pressure during the expansion process due to secondary burning of fuel leaking from the valve. Yeh Hai expansion line at the exhaust opening indicates after burning.
Hot gas from the cylinder my bro back into the leaking injector forming carbon and choking the atomizer. Karbonn me also form on the outer side of the atomizer due to burning of the dribbled fuel.
6. PARTIALLY CHOKED FUEL VALVE
It is mostly do the contamination of fuel in which the breast mate Chowk the atomizer holes. Alternatively it may also due to Vicky injector allowing hot gas to blow back into the injector causing Karbonn to form and Choke the injector.
Effect - Lawson engine power, hammering in the fuel pipes between fuel pump and injector, overheating of injector nozzle.
7. EXHAUST VALVE TIMING
This can be known by the light spring indicator diagram in a slow run slow running engine. Early opening of exhaust well will cause I lost in power since pressure is released too soon. It will give Hai exhaust temperature with risk of overheating and contamination. Late opening will reduce the Scavenger efficiency by reducing blow down.
8. CHOKED EXHAUST
The pressure drop during the valve opening does not call as rapidly as far as it should and prevents correct blowdown and recharge of cylinder with air. It causes lost in power, high exhaust temperature, smoke, possible search in turbocharger. It is the result of contamination due to incorrect combustion of excessive cylinder lubricating oil.
L= length of the stroke
A= area of piston
Pm=Mean Effective Pressure
AS PER MANUAL
As per manual
Mean indicated
pressure = (area of the curve)/(length of the curve×spring constant)
Mean effective
pressure = MIP - friction loss which is independent of load and is usually
1bar.
For power in
kw, K2= 130900*S*D2
For power in
hp, K2= 177974*S*D2
Mean indicated
power= MIP*K2*n
Mean effective
power= MEP*K2*n
3. DRAW CARD OR OUT OF PHASE DIAGRAM
Power career power cord has set and limitations that it is only used to calculate power and mean effective pressure. Since it depends on Piston movement, volume changes are very small and on either side of TDC and bdc. So it can not represent what is happening in compression and start of combustion.
If the drum is made out of phase by 90 degrees with the Piston movement, then the drum will be moving fast as the Piston comes over to TDC and bdc. This clearly illustrates the pressure changes during fuel combustion that is injection and ignition.
4. LIGHT SPRING DIAGRAM
This is again similar to the power cord and in face with the engine, but taken with the light compression spring of about 10 bar. This enables to examine what is happening around bdc that is 1 exhaust valve opens and scavenging of a takes place. Ask eastern comes up on compression, the spring will be fully compressed against the limiting stop at about 10 bar. Compression line will then stay horizontal has compression pressure increases and when expansion takes place. As the exhaust valve opens and the pressure drops below 10 by then the curve will fall and rises when scavenge opens.
IRREGULARITIES IN DIAGRAMS
1. EARLY IGNITION can be found out with power cord and draw card.
Causes - incorrect fuel pump timing comma incorrect VIT timing comma broken broken or wrong reset injector springs, incorrect fuel condition or overheating of parts within the cylinder.
Effect - this causes an abnormally high peak pressure in the cylinder at about the top of the Piston stroke due to which a heavy shock load will be transmitted to the running gear and bearings with a corresponding knocking sound. Although thermal efficiency is high and exhaust exhaust temperatures are reduced, the shock load and consequent vibrations may cause damage to the engine.
2. LATE IGNITION
Causes - it may be due to poor atomization high viscosity or poor quality fuel, fuel pump leaking or incorrectly time, low compression, insufficient supply of combustion air, or undercooling of parts within the cylinder, excessive injector spring setting.
Effects- this causes a low key pressure which occurs when after top centre of the Piston. Power is lost since the fuel is not burnt correctly to transmit power at the most effective part of the stroke. Combustion may continue during the expansion stroke and may be incomplete giving lost in energy produced, Hai exhaust temperature and smoke.
4. AFTERBURNING
This refers to slow on 8 combustion of fuel during the expansion stroke of the Piston and is shown by a rise in the expansion line during the later part of the stroke that is expansion stroke. Exhaust temperature and pressure will be hi, with burning Civil and carbon passing to exhaust. This may Ban exhaust valves and founder II exhaust system comma with risk of turbocharger surging uptake fires. High temperatures within the cylinder cause a deterioration in lubrication and possible damage to liner surface and Piston rings. This may also be burning of the Piston crown.
5. LEAKY FUEL INJECTOR
This can be detected by Hai exhaust temperature and smoke it exhaust, loss in power. As the fuel pump has to compensate the space left by licking fuel injector a sudden search in the fuel pressure wave will be occurring in the fuel line which will cause the knock. An indicator diagram taken from the cylinder will show fluctuations of pressure during the expansion process due to secondary burning of fuel leaking from the valve. Yeh Hai expansion line at the exhaust opening indicates after burning.
Hot gas from the cylinder my bro back into the leaking injector forming carbon and choking the atomizer. Karbonn me also form on the outer side of the atomizer due to burning of the dribbled fuel.
6. PARTIALLY CHOKED FUEL VALVE
It is mostly do the contamination of fuel in which the breast mate Chowk the atomizer holes. Alternatively it may also due to Vicky injector allowing hot gas to blow back into the injector causing Karbonn to form and Choke the injector.
Effect - Lawson engine power, hammering in the fuel pipes between fuel pump and injector, overheating of injector nozzle.
7. EXHAUST VALVE TIMING
This can be known by the light spring indicator diagram in a slow run slow running engine. Early opening of exhaust well will cause I lost in power since pressure is released too soon. It will give Hai exhaust temperature with risk of overheating and contamination. Late opening will reduce the Scavenger efficiency by reducing blow down.
8. CHOKED EXHAUST
The pressure drop during the valve opening does not call as rapidly as far as it should and prevents correct blowdown and recharge of cylinder with air. It causes lost in power, high exhaust temperature, smoke, possible search in turbocharger. It is the result of contamination due to incorrect combustion of excessive cylinder lubricating oil.
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