When looking at all of the components of a hydraulic hose assembly, to some, a hose is just a rubber tube. But, when choosing the components of your assembly, you need to focus on the material the tubing is constructed from, the hose fittings, and understanding what kind of application the hose will be used for.
Rarely does anyone really stop and think about how the tube is made and why. (Lucky for them, we live for this stuff.) By understanding the three main parts of a hose, you can increase the safety and performance of your entire assembly. Let’s get started! (Did we mention we live for this stuff?)
The tube is the inside component of the hose, and is the lining that comes into contact with whatever media is being moved.
Because of this contact, the material used to construct the tube is vital. If the chemical properties of the media aren’t compatible with the chemical properties of the tubing, the structural integrity of the entire hose becomes compromised. Not good.
However, the purpose of the tube goes beyond just being the lining that moves the fluid. The tube also acts as a protectant to the outer layers of the hose.
If the media passing through the tube were to seep into the other layers, an event called premeation, it could result in a loss of fluid, as well as the degradation of the outer layers. (Also not good.)
The middle layer of the hose is the reinforcement layer; it varies in construction and design depending on the application of the hose.
The main purpose of this layer is to give strength to, or reinforce, the tube layer. In most cases, the tube itself could not withstand the pressure of the fluid as it passes through. This middle layer provides the strength necessary to hold the tube together.
There are three primary reinforcement designs.
- The helical reinforcement design is used in applications where there is suction. The helix design prevents the hose from collapsing and cutting off all flow.
- The spiral reinforcement is good for extremely high-pressure applications. It’s overlapping layers, which are typically constructed from steel wire, create a powerful layer that can hold up against more aggressive applications.
- A braided reinforcement layer is used primarily in low or moderately high-pressure applications. They can be constructed in single or multiple layers, so it’s a very versatile reinforcement layer design.
The last layer of a hydraulic hose is the cover. This layer is intended to protect the rest of the hose from external forces, the environment, and add an extra level of safety.
The cover layer is often designed to withstand whatever environment the hose will be performing in.
For instance, if the hose will be exposed to extreme temperatures, the cover layer should be rated to protect the inner layers from that harsh environment.
This layer should also protect the inner layers from any abrasions or twisting the hose may suffer during use. The cover is the last line of defense for the hose, should the inner layers become compromised and a leak occurs.
How to Choose
Once you understand the construction of the hose, choosing the right hose fittings becomes equally important.
Using the best hose and fittings for your application can improve the safety and performance of the assembly as a whole.
Each component of the hose assembly is rated individually and the entire assembly is only rated as high as the lowest rated component. This means that if the hose fittings aren’t rated as high as the hose, the complete assembly rating goes down.
There are so many factors to consider when choosing the different components of an assembly that it helps to remember S.T.A.M.P.E.D. This is a common acronym used to help determine the best components for your hydraulic hose assembly by asking 7 simple questions.
Size? Temperature? Application? Media? Pressure? Ends? Duplication?
Combine S.T.A.M.P.E.D. with your knowledge of hose construction, and you will be sure to get the best hose for the job every time.