Page 469 - RYCO Hydraulics Technical Manual 2019
P. 469

1. Many factors affect the selection, making, installation and maintenance of hose assemblies. This catalogue, RYCO Hydraulics (RYCO), and The Society of Automotive Engineers recommended practice SAE J1273, have useful information about selecting, making, installing and servicing hydraulic hose assemblies. For further information, please contact your local RYCO representative.
RYCO recommends hose and coupling combinations in the catalogue only after completing extensive testing. Evaluation of a hose and coupling combination requires considerable impulse testing and cannot be determined by a simple burst or pressure hold test. RYCO disclaims all liability for any hose assembly made in violation of RYCO recommendations, procedures and current crimp data. Crimp data is updated from time to time.
The consumer’s exclusive remedy with respect to any claim shall be a refund of the purchase price or replacement of the product at the option of RYCO. In no event shall RYCO be liable for any incidental or consequential damages whatsoever.
2. The following is a list of factors which must be considered before final hose selection can be made:
2.1 Internal Pressure – After determining the system pressure, hose selection must be made so that the recommended maximum operating pressure is equal to or greater than the system pressure. Surge pressures higher than the maximum operating pressure will shorten hose life and must be taken into account by the hydraulic engineer. Hose fitting rated pressures should also be considered, as the maximum working pressure is based on the whole hose assembly and not just the hose alone.
2.2 External Pressure: In certain applications the external environmental pressures may exceed the fluid pressure inside the hose, therefore these factors need to be considered.
2.3 Suction – Hoses used for suction applications must be selected to ensure that the hose will withstand the vacuum and pressure of the system.
2.4 Temperature – Care must be taken to ensure that fluid and ambient temperatures, both static and transient, do not exceed the limitations of the hose. Special care must be taken when routing near hot objects such as manifolds.
2.5 Fluid Compatibility – Hose selection must assure compatibility of the hose tube, cover, and fittings with the fluid used. Additional caution must be observed in hose selection for gaseous applications. For full compatibility table please refer to page “Chemical Compatibility for Hose” on page 475 in the Technical Section of this manual.
2.6 Size – Transmission of power by means of pressurised fluid varies with pressure and rate of flow. The size of the components must be adequate to keep pressure losses to a minimum and avoid damage to the hose due to heat generation or excessive turbulence.
2.7 Routing – Attention must be given to optimum routing to minimise inherent problems.
2.8 Environment – Care must be taken to ensure that the hose and fittings are either compatible with, or protected from, the environment to which they are exposed. Environmental conditions such as ultraviolet light, ozone, salt water, chemicals and air pollutants can cause degradation and premature failure and, therefore, must be considered.
2.9 Mechanical Loads – External forces can significantly reduce hose life. Mechanical loads which must be considered include excessive flexing, twist, kinking, tensile or side loads, bend radius, and vibration. Use of swivel type fittings or adaptors may be required to ensure no twist is put into the hose. Unusual applications may require special testing prior to hose selection.
2.10 Abrasion – While a hose is designed with a reasonable level of abrasion resistance, care must be taken to protect the hose from excessive abrasion which can result in erosion, snagging, and cutting of the hose cover.
Exposure of the reinforcement will significantly accelerate hose failure.
2.11 Proper End Fitting – Care must be taken to ensure proper compatibility exists between the hose and coupling selected based on the manufacturer’s recommendations substantiated by testing to industry standards such as SAE J517.
2.12 Length – When establishing proper hose length; motion absorption, hose length changes due to pressure, as well as hose and machine tolerances must be considered.
2.13 Specifications and Standards – When selecting hose; government, industry, and manufacturer’s specifications and recommendations must be reviewed as applicable.
2.14 Hose Cleanliness – Hose components vary in cleanliness levels. Care must be taken to ensure that the assemblies selected have an adequate level of cleanliness for the application.
2.15 Electrical Conductivity – Certain applications require that hose be non-conductive to prevent electrical current flow. Other applications require the hose to be sufficiently conductive to drain off static electricity. Hose and fittings must be chosen with these needs in mind.
2.16 High Pressure Gas – Do not use hydraulic hose to transmit high pressure gases.

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