MEO FUNCTION IV Miscelleneous

What is the significance of different types of Indicator cards?

Different types of Indicator diagrams and their purpose:

i) Power card – To calculate indicated power. It also shows peak pressure. It is taken in phase with piston movement, with fuel on.

indicator

FIG.: POWER CARD

ii) Draw card (90 degrees out of phase)– Similar to power card but taken with the indicator drum rotation 90 degrees out of phase, with fuel on.

It shows Pmax (more accurately), P compression and ignition delay period (Nature of expansion curve). It also shows combustion process (early or late combustion)

To evaluate fuel injection process, ignition delay, fuel quality, combustion, loss of compression, expansion process, fuel pup timing, and after-burning.

indicator1

FIG.: DRAW CARD

iii) Compression diagram- It is only a line on the indicator diagram and gives the compression pressure and a timing check on the indicator cam.  It is taken in phase with fuel cut-off and at reduced RPM.

purpose 1

FIG.: COMPRESSION CARD

iv) Light spring diagram – It is taken similar to power card and in phase with engine, but with the light compression spring fitted to the indicator. It shows the pressure variations during the exhaust and scavenging operations.

indicator3

FIG.: LIGHT SPRING DIAGRAM

v) Pressure derivative card- It shows the maximum rate of pressure rise and the point of injection. It is used to highlight ignition delay.

About the author

Anand Gautam

Anand Gautam is a marine engineer, Graduated from M.E.R.I. Mumbai. He likes to sail onboard ship and is one who is passionate about his job. He loves to share his knowledge, information, and ideas to everyone in a simplified way just for his satisfaction.

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