LPG (Liquefied Petroleum Gas) is a mixture of hydrocarbon gases used as spark-ignition engine fuel. Pressure cylinders of various sizes – 2, 10 and 33 kg – are commonly filled with LPG and then used as portable heating gas storage tanks at home and when staying in the countryside. As LPG impairs natural rubber, all seals must be made of synthetic materials. The quality of LPG is determined by ČSN (Czech National Standard) EN 589. A great advantage of LPG is that its price at petrol stations is half the price of petrol (LPG is usually not burdened with high consumption tax) and that it is environmentally friendly.