Generally, a flexible rubber hose is formed by three elements, each of them has an important and specific function:
1. THE SUBSTRATE
The substrate is the inner part of the hose and must be resistant to fluids or elements conveyed. The suitable substrate allows the transport of chemical products, oil, water, steam, abrasive products, gas or other products. The substrate of the hose must be suitable for the substance conveyed. Some hoses are constituted by one layer only; they are extruded or built on mandrel with only one kind of rubber and simply externally fastened.
2. THE REINFORCEMENT
The reinforcement gives the hose the necessary mechanical strength as well as the resistance to the desired pressure. It can be obtained by using textile or other kind of inserts (nylon, amorphous fibres, steel braids) or a combination of them. If the hose must withstand aspiration (vacuum) or have an extremely high flexibility to the point it doesn’t throttle when bended, one or more metal wires should be inserted between the reinforcements to increase the resistance to collapsing.
3. THE COVERING
The covering is the external and therefore visible part of the hose. It must protect against weather, temperature influence and mechanical damages. Depending on the production method, the hose’s surface can be smooth or cloth-like. When choosing the suitable covering the choice must be made regarding the working conditions. In extreme circumstances, such as for safety reasons or for greater mechanical, chemical or structural strength, the hose can be braided outside with metal filaments or, if necessary, stainless steel ones.