FREE DELIVERY ON ALL ORDERS OVER £100.00

Please click on products below for prices & information

Unlike metal tubing, hose is flexible, so it is used primarily to allow relative motion between components at either end of the hose assembly and to simplify routing and installation. It is much easier to route a hose assembly over, under, around, or through a series of obstacles than it is to bend and install a rigid tubing assembly. Furthermore, replacing a hydraulic line by fabricating a rigid tube assembly often is more costly and time consuming than making a hose assembly.

Most manufacturers offer hose that can be bent to a tighter radius than that published in industry standards. Still, bending hose to a smaller radius than recommended should be avoided to avoid shortening service life. Therefore, route hose in a manners that provides ample bend radius.

Because hose is flexible, you must allow for contraction and expansion when cutting the hose to length. Manufacturers state that, depending on its type, hose can elongate up to 2% when pressurized, but, more importantly, can contract as much as 4%. This length differential can strain hose reinforcement wires and eventually lead to failure, especially at the hose-to-coupling interface. Therefore, cut hoses slightly longer than needed to compensate for contraction.

Bend hose in one plane only to avoid twisting its wire reinforcement, which would reduce the hose's pressure capability. Manufacturers state that twisting a high-pressure hose only 5° can reduce service life by 70%, and 7° of twist can reduce service life up to 90%. Unfortunately, hose routing usually occurs late in the design process, so it may be difficult to find an ideal path. Multi-plane bending often can be avoided by reorienting the hose, Figure 3. If this is not possible, install a hose clamp between bends, and provide enough length on both sides of the clamp to relieve strain on the hose's reinforcement wires. This length depends on the hose ID, degree of bending, and helix angle of the particular hose's reinforcing wire, so manufacturers prefer to evaluate each application individually.

Another alternative is to use a single section of hose for each bend and install a hose-to-hose coupling and hose clamp between bends. This technique is less preferred because it not only is more costly and time consuming to perform, but increases the number of potential leak points in the hose assembly. Also, to help ensure that technicians replace and secure hose assemblies properly, include detailed instructions on hose length, use of hose clamps, and special considerations in service manuals.