» How your Cylinder works
An LPG cylinder is a pressure vessel made from 2 to 3mm mild steel plate and of welded construction. The surface of a cylinder in direct contact with the LPG is known as the wetted area.
A ‘Full’ cylinder is not full of liquid, the space is left for expansion of the liquid and a supply of compressed vapour in the space above the liquid level.
The percentage fill varies with the size of cylinder, but normally has a maximum fill of 80 to 87%.
When the valve is opened, LPG is pushed out of the vessel bu the pressure and, as a result, the pressure above the liquid is reduced.
The liquid takes in heat from the cylinder and the outside atmosphere and begins to boil, giving off vapour.
As the conversion of liquid to gas continues, the liquids level slowly falls. When the valve is closed again the pressure inside will rebuild up to the vapour pressure of the liquid, irrespective of how much liquid is left in the container.
