Gas Laws

Question 1

Explain - Boyles Law

Answer 1

This states that the volume of a mass of gas is inversely proportional to the pressure, if the temperature is maintained constant. P1 x V1 / T1 = P2 x V2 / T2

Question 2

What is Diffusion

Answer 2

Two gases in contact with each other will slowly diffuse (mix) into each other. This movemet occurs even in opposition to gravity or buoyancy. The lighter the gas the more rapidly it diffuses. The rate of diffusion is inversely proportional to the square root of density, therefore lighter gases diffuse faster than heavier gases.
Remember - The prinicple method of diluting gases or removing gas layers or accumulations is by ventilation qauntity and turbulence. Diffusion is a secondary method used to dilute methane concentrations.

Question 3

Explain Buoyancy

Answer 3

Buoyancy is the phenomenen whereby the combination of gas properties and seam gradient can allow gas to migrate against the flow of ventilation. This can both help and hamper gas management. This bouyancy effect can also cause air to reverse when breaching seals or holing into goaf areas and fluch out irrespirible atmospheres into the workings. This can happen if the ventilating pressure is not great enough to overcome the effects of the denisty of other gases.
Remember - it is possible for a gas to layer against the flow of ventilation.