Hi All,This thread was annoying me left like it is and overly...

Hi All,
This thread was annoying me left like it is and overly complicated. Hopefully I can help clarify based on my understanding/research.
As a few have stated previously (RBocky, BigKev14, AM27) and to link their posts. The C rating mentioned in the announcement has nothing to do with gases but the visual coal attributes, specifically cleat density.

Source - Ground Engineering - Principles and Practices for Underground Coal Mining By J.M. Galvin


Forget anything about gasses. Hydrocarbons do not have anything to do with this except that we want one to flow (methane). It is a pure coincidence that hydrocarbons/fuels (gas and liquid) are also measured on a C scale (based on weight I think), which has caused confusion with other posters research.
Below image to help substantiate my above statement.


Now the questions is how good do C3-C4 class coals flow? And I do not believe their is a straightforward answer as many other micro and macro factors are in play. You could say we have the variance of 10-60% bright over a 50m seam, alternatively 40-90% dull.

This is definitely worth a read and re-read.
Coal type, microstructure and gas flow behaviourof Bowen Basin coals by P.D. Gamson and B.B. Beamish
Abstract image to encourage a read.


I will leave it up to you all to make your own summaries on what coal brightness/cleating you think will help best short and long term solid gas flow.

Good Luck