Transcript Document
LESSON FIFTEEN STARTING AIR SYSTEM 1. ENGINE STARTING An engine can be started manually, electrically or by compressed air & remote air starting valve. 2. AIR RECEIVER VOLUME To start a reversible engine 14 – 16 times consecutively To start a unidirectional engine 7 – 8 times consecutively 1. ENGINE STARTING An engine can be started manually, electrically or by compressed air & remote air starting valve. 2. AIR RECEIVER VOLUME To start a reversible engine 14 – 16 times consecutively To start a unidirectional engine 7 – 8 times consecutively 3. COMPRESSED AIR ENGINE STARTING Minimum cylinder number: Four stroke single acting ...... 6 Four stroke double acting ..... 3 Two stroke single acting ....... 3 Two stroke double acting ...... 2 4. OPERATING SYSTEM COMPONENTS AND FUNCTION 4.1 A compressor is a machinery, reciprocating or rotary, that is used to increase the pressure of gas. The pressure varies between 3-6 MPa. If higher a throttle valve must be built-in between the air receiver & the remote air starting valve. 4.2 Air receiver / starting air receiver / starting air vessel may be defined as a vessel for storing compressed air. 4.3 Pilot valve control valve / control valve is a quick operated, spring loaded valve actuated by starting air lever. As the control valve is operated, it causes the automatic valve / remote operating non-return valve to open allowing the main starting air / pilot air to pass to the air start manifold. 4. OPERATING SYSTEM COMPONENTS AND FUNCTION 4.1 A compressor is a machinery, reciprocating or rotary, that is used to increase the pressure of gas. The pressure varies between 3-6 MPa. If higher a throttle valve must be built-in between the air receiver & the remote air starting valve. 4.2 Air receiver / starting air receiver / starting air vessel may be defined as a vessel for storing compressed air. 4.3 Pilot valve control valve / control valve is a quick operated, spring loaded valve actuated by starting air lever. As the control valve is operated, it causes the automatic valve / remote operating non-return valve to open allowing the main starting air / pilot air to pass to the air start manifold. 4.4 Remote operating non-return air starting valve is a valve which: a) prevents the return of air into the system ; b) supplies the air to the cylinder air starting valves; c) provides air for astern / ahead operation. 4.5 Interlock or blocking devices prevents operation of the pilot air control valve in following cases: a) turning gear being engaged, b) direction controls are incorrectly set, c) fuel control wrongly positioned or d) essential engine systems failure. 4.5 Interlock or blocking devices prevents operation of the pilot air control valve in following cases: a) turning gear being engaged, b) direction controls are incorrectly set, c) fuel control wrongly positioned or d) essential engine systems failure. 4.6 Timing valves / distributor are synchronised with the engine possition through cams or gear drive from the camshaft in order to admit the air into each cylinder air start valve in the correct order and timing as the engine rotates. 5. TROUBLES 5.1 Air leaking start valve Is detected by an increase of temperature of valve and start air pipe adjacent to it. The leaking is caused by build up of carbon which may eventually result with an air starting line explosion when the engine has been stopped or re-started while hot. To prevent it, the pipeline is to be kept clean and fitted with flame traps and relief valves. 5. TROUBLES 5.1 Air leaking start valve Is detected by an increase of temperature of valve and start air pipe adjacent to it. The leaking is caused by build up of carbon which may eventually result with an air starting line explosion when the engine has been stopped or re-started while hot. To prevent it, the pipeline is to be kept clean and fitted with flame traps and relief valves. 5.2 Presence of water Compression and cooling of air leads to presence of water in the compressed air system. In order to eliminate it, the recivers are usually fitted with drains.