Wednesday, November 5, 2014

Industrial Hose Service Life

All rubber products, including Industrial hose assemblies, have a limited life on a given application. Assuming the correct hose has been selected for the application, this service life can be adversely affected by many variable conditions. The major ones are:
o   Exposure to severe external abuse such as kinking, bending, high end pull, crushing or abrasion
o   Exposure to higher than rated working pressures or  to high surge pressures
o   Exposure to higher than rated temperatures
o   Misapplications or exposure to corrosive liquids or gases outside the range of suitable applications.

External abuse – hoses should be placed where they will not be run over by equipment or subjected to high end pull. Hoses should not be bent below recommended minimum bend radius. This could result in kinking the hose or reducing its pressure resistance. Large diameter hoses also may require additional support to reduce the external abuse

Hose and system pressures – In establishing and determining pressures related to hose and the systems to which they are applied, it is necessary to consider separately the characteristics of the hose and the system.
o   The system (or device or applications) can have several pressures depending on pressure sources and surges imposed by the operator or mechanical components.
o   A given hose has a fixed characteristic with respect to the pressure it can withstand (and how it is applied) and still give satisfactory life

High Temperatures - The allowable temperature ranges for industrial hoses are shown on the High Temperature Ranges page. These are for product temperatures and should not be exceeded. High temperatures can degrade rubber stocks very quickly resulting in short service life. Where external temperature are higher than normal ambient, contact your Gates field representative for recommendations.

Misapplications – All industrial hoses are designed for certain specific application or related application. They should not be used for any other applications.

Hose Information – Refer to the Gates Industrial Hose Catalog for detail of hose constructions and physical characteristics. These are shown in the data pages and include such items as rated working pressure, vacuum rating, maximum bend radius, and static conductivity.

Internal Abrasion – For applications of a highly abrasive nature where the hose makes one or more bends, the hose should be rotated 90 degrees periodically to lengthen service life.
The hose manufacturer established, through design and testing, the recommended rated working pressure for the hose. It is the responsibility of the user to accurately determine the system pressure. Steady state pressure can be measured readily by gauges. Surges are difficult to measure and may require the use of electronic pressure pickup devices. Also, surge values depend on so many variables that a series of tests are usually required to obtain a valid set of readings. However, if there are extreme surges in the normal operation or if there is the likelihood of abnormal operation of the system, the magnitude must be determined.

Considering the recommended rated working pressure of the HOSE and the various pressures of the SYSTEM, the hose is matched to the system using proper application engineering principles. End terminations may reduce the rated working pressure of hose assemblies. Refer to coupling manufacturer for recommendations.

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