Page 128 - Mechanic Diesel - TT

MECHANIC DIESEL - CITS

This separates the water content of the fuel. it is a transparent bowl made of glass or plastic. since water is
heavier than diesel in this, it stays at the bottom and the top diesel moves forward. a drain plug is provided to
drain the water
Feed Pump/Lift Pump
A vacuum is created in the pump and the fuel is drawn from the tank and delivered to the fuel injection pump at
low pressure through the primary and secondary filters. When FIP does not consume fuel. At that time the feed
pump is working in idling state. A priming pump is provided to remove air from the fuel system when the engine
is shut down (air lock).
Which delivers the fuel in this tank to the FIPs when the engine is off.
Fuel Filter
A fuel filter is installed to ensure that pure diesel is supplied to the diesel engine. Feed pump, f.i. clearance
between moving parts in pump and injector is very less. If dirt or debris gets stuck in the four microns, the part
cannot function properly.

Fuel due to which filters come in two types, single and double. A no hole fuel filter is mounted on the chassis or
bolted to the engine. Which should be planted in four microns. Filtering
Fuel injection pump

This pump is used to supply diesel to the injectors before the piston reaches TDC at the end of the compression
stroke. This pump supplies diesel to each injector as per engine requirement and firing order at a pressure of
about 200 bar. This also shuts down the engine.

Fuel injector
F. A fuel injector is mounted on the cylinder head to spray high pressure fuel from the eye pump into the combustion
chamber. Diesel is sprayed uniformly throughout the combustion chamber by the fuel injector. This completes the
combustion by mixing with sufficient oxygen and thereby reducing the amount of carbon.

Diesel fuel & its properties combustion processes

Objectives: At the end of this lesson you shall be able to
• explain properties of Diesel fuel
• explain Cumbustion process.

Diesel Fuel Properties
1 Chemical Composition: Diesel fuel is composed of hydrocarbons obtained by fractional distillation of
crude oil.
2 Density: It is denser than petrol, meaning it contains more energy per unit volume.
3 Energy Density: It has higher energy density than petrol, so it is more efficient for heavy duty uses.

4 Viscosity: Diesel fuel is more viscous or thick, which affects its flow.
5 Combustion Temperature: Diesel fuel requires a high temperature to catch fire because of its low volatility.
6 Sulphur Content: Diesel fuel used to have a high Sulphur content, but regulators have reduced Sulphur levels
for environmental reasons.
7 Cetane Number: Cetane number is a measure of the flame quality of diesel fuel. Higher Cetane numbers
indicate better flame quality.
8 Flash Point: Diesel fuel has a higher flash point than petrol, which means it requires a higher temperature to
burn.
9 Colour: Diesel fuel ranges from light to dark brown.
10 Storage Stability: Diesel fuel has good stability during storage, but if not handled properly, it can degrade over
time due to the growth of contaminants or oxidation.

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CITS : Automotive - Mechanic Diesel - Lesson 31 - 38