Working with hydraulic products and machines requires care, precision work and regular maintenance. This prevents unnecessary costs and reduces the risk of accidents and production interruptions. During repair and maintenance work, the importance of using appropriate materials is often underestimated.
It seems innocent enough: using a brand A coupling on a brand B hose. Even though it seems to fit perfectly in the beginning, there is a high risk of this leading to problems and dangerous situations. That is not to say that there is a difference in quality between the manufacturers — the components simply don't always work well together. Swage data, hose lines, hoses and couplings differ from one manufacturer to the next and are not interchangeable. When parts from different manufacturers are used on one installation, there is a very real risk of the hose slipping out of the coupling. This can be dangerous for whoever is using the installation and can also have a seriously detrimental effect on the service life and performance of machines. And let us not forget that any form of warranty is invalidated as soon as parts from other manufacturers are used.
Choosing a hose
Not all hydraulic hoses are the same. Different working conditions require different hoses. Put simply, a hydraulic hose consists of three parts: the outer wall, the reinforcement and the inner tube.
The outer wall protects the reinforcement and the inner wall against outside influences, such as UV light, wear, weather conditions and chemicals. A different outer wall may be required for each situation.
The reinforcements ensure that the hose can withstand internal pressure and vacuum. There are three types of reinforcement: braided, coiled and steel wire spiral. Once again, the intended use of the hose determines which type of reinforcement is most appropriate.
- Flow: Determine the correct hole diameter in order to work efficiently
- Coupling: Determine the type of threaded connection on the system and the coupling that corresponds to this type
- Fluid: The inner and outer wall of the couplings in 'O' rings must be resistant to the fluid used
- Pressure: Make sure that the system pressure and the peak pressures are known
- Application: What will the hose be used for? Type of machine, bend radius etc.
Choosing a coupling
A hydraulic coupling has two ends: the flange or threaded connection for connecting to the installation and the swage coupling for attaching to the hose. The dimensions of the hose determine the size of the end that is pushed onto the hose. The type of hose coupling depends on the manufacturer. As mentioned earlier, it is important to use materials from a single manufacturer, as they will be fully compatible with each other.
Storing hoses
Store hoses in a cool, dry environment and away from direct sunlight. Avoid contact with harsh chemicals and ultraviolet light. Please pay attention to stock management. Fittings with 'O' rings must not be kept in storage for more than two years.
Installation tips
To ensure full capacity can be achieved, it is important to install a hose line properly. If the hose is too short, it will lack the necessary flexibility: it must be able to bend as well as expand and contract. A hose that is too long may result in the system not working properly and unnecessary costs will be incurred.
With a straight hose line, there must be enough play to accommodate pressure distribution. Ensure that the hose is not too short.
Never secure a hose in a bent position, as a hose changes under pressure. A minimum length of 1.5 x the diameter of the hose must be maintained as a straight line after the fitting. Only bend the hose after this length.
- Clean the machine at the points where a hose needs to be fitted. This prevents contamination in the hose.
- Place the hose in the right position to determine whether the right length has been selected.
- When both ends are connected, allow the oil to flow through at low pressure and check for leaks. This also ensures that the air is pushed out of the tubes, thus improving performance.
- When everything is connected, inspect the entire system regularly. Take ample time for the first inspection. After this inspection, the user will know how everything looks and how it is meant to sound. During subsequent inspections, this can be used as a guide and any problems can be detected quickly.
- All hydraulic hoses have a limited service life, which can be affected by various factors, such as temperature and handling of the hose.
The main causes of faulty hydraulic hoses:
1. Misuse
2. Incorrect application
3. Incorrect hose routing
Would you like more information about working with hydraulics? Look no further! Our hydraulics staff are always ready to help.
* This article previously appeared in Kramp Focus Edition 2 2017
