4_Air_Starting_System_components slide show

4_Air_Starting_System_components slide show

1. Air Starting System
Design & operation details of various parts of the system may
differ according to engine manufacturer.
But basic function within the system is essentially same in all
makes of engine.
Main Components
 Air receiver
 Automatic valve
 Starting air distributor
 Starting air valves

2. Main Components of Air Starting System
Leak test
valve

3. Air Starting System
Air Receiver

At least two air receivers with air pressure 25 – 30 bar
and sufficient capacity without replenishment will able
to provide:
6 starts for non reversible engine
12 starts for reversible engine

4. To supply air automatically for
starting engine
Quickly shut off starting air
when engine is running on fuel
For safe running & conserve
starting air
Normally hand wheel is set to
automatic position
In emergency, automatic valve
can be operated manually
Must be locked shut during
maintenance & prior engaging
turning gear
Automatic Valve

5. Starting Air Distributor
To ensure opening of starting air
valves on cylinders in correct
sequence according to firing order.
Types of distributors:
 Circular disc with suitable ports
 Spool type valve radially around
central cam
 Spool type valves laterally
above sliding camshaft
Distributor cam is negative type
cam.

6. Starting Air Valve
Fitted in each cylinder cover

Timing of opening & closing is
controlled by cam
Balance piston & valve head are of
same nominal dia. In order to hold
the valve in balance when main air
is open
Spring holds the valve closed
Guide ensures correct alignment of
valve
Periodical routine check is
necessary for any leakage

8. Air Starting System
Pilot Valve
Operation of the v/v vents compressed air from actuating
piston in automatic v/v & causing it to open
Action of pilot v/v also controls air supply to distributor
Controlled directly by starting lever or indirectly by
solenoid control

9. Air Starting System
Non Return Valve
Located between engine and automatic starting air valve
Robust in construction
Prevents air starting line explosion getting back to air receiver
Contains explosion in short length of pipe as it is fitted close
to engine

10. Air Starting System
Relief Devices
It is located on the starting air manifold, between non return
valve & cylinder air starting valve.
 Spring loaded relief valve
to guard against overpressure
resets automatically
but open to tampering

 Bursting disc
relatively tamper proof
unlike relief v/v doesn’t reset – needs blanking off for restarting

11. Air Starting System
Problems
 Sluggish operation of starting air and distributor valves due
to dryness and rust
 Leaky valves
Cause
Moisture contained in air carries away the lubricant and causing
sticky / frozen valve.
Effect on engine
 Engine cannot start and wastage of starting air
 Gas leakage may cause explosion hazard

12. Leak Test of Air Starting Valve
 Ensure turning gear is disengaged
 No one is working in crankcase or on the engine
 Obtain propeller clearance from bridge
 Close shut off v/v for the distributor
 Keep indicator cocks open
 Open main air stop v/v & automatic v/v
 Put maneuvering handle to start position
 Leaky v/v will be indicated from indicator cock

13. Engine fails to start on air
Turning gear engaged
Water collected on top of piston
No & bar control air, 30 bar starting air
No electrical power supply to remote control unit
Solenoid operated valve problem
Distributor, reversing mechanism, pilot valve
stuck