Understanding the difference between single-jacketed and double-jacketed fire hoses is important to make what is right for your project and application. If you are not familiar with purchasing hoses, you may be surprised to find that although there are some attributes that can separate these hoses, their construction is relatively similar. The single-sheathed hose and the double-sheathed hose are composed of the same two parts: the inner lining and the outer sheath. The inner lining of modern fire hoses is a layer of EPDM rubber. Characteristics of EPDM rubber. Although the rubber lining itself is designed to have a tensile strength of 1800 PSI, it will not maintain fluid pressure. Without the jacket, the tube itself would burst like a balloon! Lining and passing through the jacket. They are then subjected to a steam vulcanization process, and the circular loom manufacturer glues the jacket to the lining. The woven jacket is composed of ring-spun polyester yarn and is designed for mold and mildew. These jackets are woven on large circular looms that are specific to the size they will become fire hoses. The jacket provides strength and pressure for the hose. Although most jacketed hoses are white, there are many colors to choose from. To achieve coloration, the jacket is impregnated with dye, also known as hypalon coating. Simply put, the difference between a single jacket and a double jacket fire hose is the number of polyester jackets. Double-sheathed hoses have an additional layer of fabric ("sheath"), which is high compared to single-sheathed hoses. It has impressive burst tests of 1,200 PSI and 400 PSI service tests. In contrast, a single sheathed fire hose has undergone blasting tests and reached 900 PSI.