As Second Engineer, instructed to submit to the Superintendent Engineer a complete indicator card together with relevant data. Give a full account of the work in taking the cards and preparing them for submission. Tabulate the data forwarded, both extracted from the cards and otherwise obtained, giving typical figures from a motor ship.
Work in taking the cards:
- Preparation: The engine is brought to a steady load (e.g. the service load) and the engine is running steadily. The indicator cocks on the cylinders are opened, and the indicator (mechanical) or the electronic draw card system is prepared. The indicator is fitted to the indicator cock of each cylinder in turn.
- Taking the cards: For each cylinder, the indicator card (P-V diagram) is taken by connecting the indicator to the cylinder and allowing the piston of the indicator to trace the pressure variation on the card. The card is taken at the correct scale (spring selection) so the pressure is recorded accurately. The cards are taken for all cylinders at the same load.
- Recording data: While taking the cards, the following data is recorded: the engine speed (rpm), the engine load (fuel index/rack position), the brake power (from the engine log or the shaft power), the exhaust temperatures of all cylinders, the jacket cooling water temperatures, the scavenge air pressure, the fuel consumption, and the ambient conditions.
- Preparing the cards for submission: The cards are removed from the indicator, marked with the cylinder number, the date, the load, and the scale. The cards are analysed: the mean indicated pressure (MIP) is measured (by planimeter or by the electronic system), the indicated power of each cylinder is calculated, and the maximum pressure (Pmax) and the compression pressure are read from the card. The cards are then compiled with the data for submission.
Data forwarded (tabulated):
From the cards:
- Mean indicated pressure (MIP) per cylinder (bar)
- Indicated power per cylinder (kW)
- Total indicated power (kW)
- Maximum combustion pressure (Pmax) (bar)
- Compression pressure (bar)
- Indicated specific fuel consumption (ISFC) (g/kWh)
Otherwise obtained:
- Engine speed (rpm)
- Brake power (kW)
- Fuel consumption (kg/h) and specific fuel consumption (SFOC) (g/kWh)
- Exhaust temperatures per cylinder (deg C)
- Jacket cooling water inlet/outlet temperatures (deg C)
- Scavenge air pressure (bar) and temperature (deg C)
- Charge air pressure and temperature
- Lubricating oil pressure and temperature
- Ambient air temperature and pressure
Typical figures from a motor ship (e.g. a 6-cylinder slow-speed engine at 85% MCR):
- Engine speed: 100 rpm
- Brake power: 12,000 kW
- MIP: 16 bar
- Pmax: 130 bar
- Compression pressure: 80 bar
- Exhaust temperature: 350 deg C
- Jacket water outlet: 80 deg C
- Scavenge air pressure: 2.5 bar
- SFOC: 170 g/kWh
The cards and the data are compiled and submitted to the Superintendent, with the cards showing the cylinder balance and the engine condition.