Most gas hoses comprise three layers. These can be made of:
The outer layer of LPG hoses is often made of PVC (polyvinyl chloride), which is a type of plastic. PVC is flexible and offers good resistance to the corrosive effects of LP gas. However, it’s not as tough as synthetic rubber and is usually found on cheaper hoses.
The middle layer of high quality hoses may be made of stainless steel braid for extra strength. It’s resistant to rust, so will last a long time.
Sometimes the outer layer is also stainless steel. This makes for a tough, durable hose that is particularly suitable for long term outdoor use, for instance on caravan changeover regulators. It’s weather resistant, can’t be gnawed by animals and will last up to twenty years – unlike nitrile, PVC or rubber hoses, which should be changed every five years.
The inner core of most modern gas hoses is made of a synthetic rubber called nitrile, also known as NBR (nitrile butradine rubber). It’s often used for the outer layer as well. Nitrile is made from gases created during the process of refining petroleum, and is widely used because it’s much stronger than natural rubber, can be stretched into many different shapes and is highly resistant to both LP gas and oil.
Some gas hoses are reinforced with a braided middle layer made of polyester, which is a versatile synthetic textile made from plastic. It’s resistant to gas, but obviously not as durable as stainless steel braiding.
Natural rubber is still used to make the inner core of some hoses. It starts off as liquid latex, which is a white milky substance tapped from rubber trees (hevea brasiliensis). The latex then goes through several chemical and mechanical processes to make solid rubber.Rubber isn’t as popular as synthetic versions because it’s less resistant to corrosion and less flexible. The limited supply also makes it more expensive. About 200 other plants also contain liquid latex, but many of them are very small and it’s not cost-effective to tap them.