**Gesang Technical Manual – Hose and Joint Foundation**
1. **Hose Construction**
A typical rubber hose consists of three main layers: an inner layer made of synthetic rubber that contains the fluid, a reinforcement layer composed of steel wires or fibers to withstand internal pressure, and an outer protective layer of synthetic rubber to shield the hose from external damage. These layers are designed to ensure durability, flexibility, and resistance to environmental factors.
2. **Working Pressure**
When selecting a hose and its fittings, it is essential to ensure that the maximum recommended working pressure of the assembly is equal to or greater than the system’s maximum operating pressure. Additionally, any pulse or peak pressure in the system must not exceed the hose’s maximum working pressure to avoid failure.
3. **Test Pressure**
The test pressure is typically conducted at room temperature using water or another suitable medium. The hose assembly should be pressurized to twice the working pressure for 30 to 60 seconds without leakage or pressure drop. This test follows the ISO 1402 standard to verify the integrity of the assembly.
4. **Burst Pressure**
Burst pressure refers to the pressure at which the hose would rupture. It is generally required to be at least four times the rated working pressure. However, this value is not used as a selection criterion during testing but rather as a safety margin in design.
5. **Fluid Compatibility**
The hose must be chemically compatible with the fluid it will carry. Incompatible fluids can cause degradation, premature aging, or failure of the hose, leading to system malfunction or leaks. Always check the manufacturer’s compatibility charts before installation.
6. **Temperature Range**
To maintain optimal performance, the temperature of the fluid and the surrounding environment must stay within the hose’s specified range. Exceeding these limits can accelerate aging and lead to leaks or structural failure.
7. **Minimum Bend Radius**
The minimum bend radius is the smallest radius the hose can be bent while still maintaining its performance under rated working pressure. Bending beyond this limit can weaken the hose and cause failure. Also, the straight section between the hose and the fitting should be at least 1.5 times the hose’s outer diameter.
8. **Storage of Hoses and Joints**
Proper storage is crucial to ensure the longevity of hoses. According to DIN 20066:2002-10, hoses should be stored for no more than 4 years from the production date, while hose assemblies should not be used after 6 years from their production date. The storage period itself should not exceed 2 years.
ISO/TR 17165-2 provides slightly different guidelines, stating that hoses and assemblies should not be used after 10 years from the manufacturing date.
This manual serves as a reference guide for safe and effective use of hoses and joints. For further information, please visit: [http://news.chinawj.com.cn](http://news.chinawj.com.cn)
Shanghai Gesang Electromechanical Technology Co., Ltd.
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