The correct installation of hydraulic hoses is a critical step in ensuring that your hydraulic equipment runs efficiently and reliably. For many systems, flexible hoses are much easier to route and assemble than rigid pipes, and they allow for some movement. They are also faster and simpler to replace. However, there are still rules that must be followed when it comes time for hydraulic hose installation to maximize the service life of the hose assembly and prevent unnecessary pressure losses.
Avoiding Hose Twist When Installing Hydraulic Hoses
If you want your hoses to last and cause minimal pressure losses, then avoid twisting the hose. A hydraulic hose should be bent in one plane only. Also, make sure to account for moving parts that may cause twisting later on.
The labeling or writing on the side of a hydraulic hose can be used as a guide which helps ensure that the hose is not twisted. If you do end up with a twisted hose, then hold the ends and tighten the connections again using a pair of wrenches. One wrench is used to keep the hose from twisting while the other is used to tighten the connection. This is referred to as “double wrenching.”
Using the Proper Bend Radius
For proper hydraulic hose installation, never use a bend radius smaller than the one recommended for the type of hose you are using. Using a radius less than recommended will not only result in a shortened service life for the hose but will also cause the hydraulic system to experience pressure losses in that section. Tight bends can be used, but they may cause problems in the long run.
Here’s another tip to keep in mind: after a ferrule, which is a metal band that strengthens the hose and/or attaches two pieces of hose together, a straight section of hose that is about 2 x the outside hose diameter should precede any bends. If this rule is not followed, then high-speed fluid will impact the bend and eventually cause core tube failure, besides the pressure losses involved.
Accommodating Movement During Hydraulic Hose Installation
There will be some movement of hoses when the hydraulic system is running. The careful use of bends (using the proper bend radius, of course) can prevent the hoses from experiencing excessive tension or compression. This also helps to absorb sudden impact loadings that can occur at system startup.
Proper Hose Length and Installation
The hose assemblies should be long enough that the minimum bend radius is met. Hoses should never be so short that the hose makes a right angle at the connectors. It is also important to make the hoses long enough to account for potential expansion or contraction when the hydraulic system is in use.
On average, hoses can change length by 2% to 4% when pressurized. This means a 24” hose could change in length by an inch. Even if the hose is just being used for a straight-line connection, it still needs to be a cut a little longer than necessary.
When routing flexible hoses, it is important to avoid allowing the hose to interact with an object that could run against it. For example, routing a hose next to a part that moves or vibrates will result in abrasion that can in turn lead to wear and a leaking hose. Hoses can also rub against each other, causing abrasions. One solution to abrasion issues is careful routing. However, if routing the hose away from the problem area is not feasible, then consider clamping.
Routing and Clamping During Hose Installation
Clamping may be done to prevent abrasion or contact with hot regions of the equipment, or to provide hoses with support.
The key thing to remember about clamping hoses is that they can shorten and lengthen during operation, so do not clamp them too tightly. Also, hoses should be clamped separately to prevent abrasion.
If abrasion cannot be avoided, or if hoses must be run near high-temperature components, then hose covers are recommended. It is much cheaper to install a hose cover than to repair a hose that has a hole worn in it or whose exterior has melted.
One of the major causes of hydraulic system failure is contamination. All new hoses should be cleaned before they are installed. Hydraulic contamination can be introduced when the hose is being manufactured, or when it is being cut to fit an assembly.
The easiest way to clean the shorter hoses is to use high-pressure air to blow any contaminants through the hose out the other end. For longer hoses, a compatible fluid can be used to flush them out. However, any fluid used must be filtered first, or there is a risk of introducing new contamination.
An alternative way to clean out hoses is to use a foam projectile that is shot through the hose using an inert gas or pressurized air.
Planning for Future Maintenance and Ease of Accessing Hoses
When designing the hydraulic hose installation for a hydraulic system, it is important to keep in mind future maintenance. A hose may be easy enough to install, but how hard will it be to replace? A manifold may look aesthetically pleasing with the hoses neatly stacked with the same tube fittings. However, accessing a hose in the back might require that all hoses in front of it be removed in order to reach the target hose. A better solution might be to use different tube fittings and hose lengths to make later access easier.
Your First Choice for Hydraulic Hose Installation, Repair & Maintenance
Best practices like avoiding hose twists, using the correct bend radius, accounting for hose contraction/extension, and avoiding abrasion can significantly extend the useful life of your hose assemblies and reduce your machine downtime. The experienced technicians from MAC Hydraulics will come to your facility and handle your hose installation, preventative maintenance, replacement, and repair. Our staff will work with you to develop a personalized maintenance plan that meets your needs and objectives. Contact us today at MAC Hydraulics!