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Hydraulic hose to SAE/DIN/EN > Recommended Practices - page 2

  Hydraulic hose to SAE/DIN/EN
Recommended Practices - page 2

5.16 Hose Cover Protection
Protect the hose cover from abrasion, erosion, snagging and cutting. Special abrasion-resistant hoses and hose guards are available for additional protection. Route hose to reduce abrasion from hose rubbing other hose or objects that may abrade it.

5.17 External Physical Abuse.
Route hose to avoid :
a. Tensile loads
b. side loads
c. flattening
d. Thread damage
e. kinking
f. damage to sealing surfaces
g. abrasion
h. twisting

5.18 Swivel-type adapters
Swivel-type fittings or adapters do not transfer torque to hose while being tightened. Use these as needed to prevent twisting during installation.

5.19 Live Swivels
If two components in the system are rotating in relation to each other, live swivels may be necessary. These connectors reduce the torque transmitted to the hose.

5.20 Slings and clamps
Using slings and clamps to support heavy or long hose and to keep it away from moving parts. Use clamps that prevent hose movement that will cause abrasion.

5.21 Minimum bend radius

Figure 1. Minimum bend radius
The minimum bend radius is defined in SAE J343 and is specified in other SAE standards and hose manufacturer's products literature. Routing at less than minimum bend radius may reduce hose life. Sharp bending at the hose/fitting juncture may result in leaking, hose rupturing or the hose assembly blowing apart (see 4.2 and Figure 1).
5.22 Elbows and adapters

Figure 2. Elbows and adapters
In special cases, use elbows adapters to relieve hose strain (see Figure 2).

5.23 Lengths
Unnecessary long hose can increase pressure drop and affect system performance. When pressurized, hose that is too short mau pull loose from its fittings, or stress the fitting connections, causing premature metallic or seal failures. When establishing hose length, refer to Figure 3, 4, dan 5; and use the following practices.

5.23.1 Motion absorption

Figure 3. Motion absorption
Provide adequate hose length to distribute movement and prevent bends smaller than the minimum bend radius.
5.23.2 Hose and machine tolerances

Figure 4. Hose and machine
Design hose to allow for changes in length due to machine motion and tolerances.

5.23.3 Hose length due to pressure

Figure 5. Hose length due to
Design hose to accomodate length changes from changing pressures. Do not cross o clamps together high and low pressure hoses. The difference in length changes could wear the hose covers.

5.24 Hose movement and bending
Hose allows relative motion between system components. Analyze this motion when designing hose systems. The number of cycles per day may significantly affect hose life. Also avoid multiple planes of motion and twisting motion. Consider the motion of the hole when selecting hose and predicting service life. In applications that require hose to move or bend, refer to

Figures 6 and 7 and use these practices.

5.24.1 Bend in only one plane to avoid twisting

Figure 6. Bend in only one plane
to avoid twisting
5.24.2 Prevent hose bending in more than one plane

Figure 7. Prevent hose bending in
more than one plane
If hose follows a compound bend, couple it into separate segments, or clamp it into segments that flex in only one plane.

6. Hose-Assembly Fabrication
Persons fabricating hose assemblied should be trained in the proper use of equipment and materials. The manufacturers' instructions and the practices listed as follows must be followed. Properly assembled fittings are vital to the integrity of a hose assembly. Improperly assembled fittings can separate from the hose and may cause serious injury or property damage from whipping hose, or from fire or explosion of vapor expelled from the hose.

6.1 Component Inspection
Prior to assembly, examine components for:
a. Style or type
b. Cleanliness
c. Loose covers
d. Nicks
e. Size
f. Inside obstructions
g. visible defects
h. damage
i. length
j. blisters
k. burrs

6.2 Hose Fittings
Hose fitting components from one manufacturer are not usually compatible with fitting components supplied by another manufacturer. For example, do not use a hose fitting nipple from one manufacturer with a hose socket from another manufacturer. It is the responsibilty of the fabricator to consult the manufacturer's written instructions or the manufacturer directly for information on proper fitting components.

6.3 Hose and Fitting Compatibility
Care must be taken to determine proper compatibility between the hose and fitting. Base selection on the manufacturer's recommendations substantiated by testing to industry standards such as SAE J517. Hose from one manufacturer is not usually compatible with fittings from another. Do not intermix hose and fittings from two manufacturers without aproval from both manufacturers.

6.4 Hose Assembly Equipment
Assembly equipment from 0.16 manufacturer is usually not interchangeable with that from another manufacturer. Hoses and fittings from one manufacturer should not generally be assembled with the equipment of another manufacturer.

6.5 Safety Equipment
During fabrication, use proper safety equipment, including eye protection. breathing apparatus, and adequate ventilation.

6.6 Reuse of Hose and Fittings
When fabricating hose assemblies, do not reuse :
a. Field-attachable fittings that have blown or pulled off hose.
b. Any part of hose fittings that were permanently crimped or swaged to hose.
c. Hose that has been in service after system checkout (see 7.7)

6.7 Cleanliness of Hose Assemblies
Hose assemblies may be contaminated during fabrication. Clean hose to specified cleanliness levels (see 5.13)

7. Hose installation and replacement
Use the following practices when installing hose assemblies in new systems or replacing hose assemblies in existing systems.

7.1 Pre-Installation Inspection
before installing hose assemblies, examine :
a. Hose length and routing for compliance with original design
b. Assemblies for correct style, size, length, and visible non conformities.
c. Fitting sealing surfaces for burns, nicks, or other damage.
NOTE: When replacing hose assemblies in existing systems, varify that the replacements is of equal quality to the original assembly.

7.2 Handling During Installation
Handle hose with care during installation. Kinking hose, or bending at less than minimum bend radius may reduce hose life. Avoid sharp bending at the hose/fitting juncture (see 5.21)

7.3 Twist Angle and Orientation

Figure 8. Twist angle and orientation
Pressure applied to a twisted hose may shorten the life of the hose or loosen the connectors. To avoid twisting, use the hose lay line or marking as a reference (see Figure 8).