QUALITY FACTORS
QUALITY FACTORS
SAFETY WARNING: IMPROPER SELECTION, INSTALLATION OR MAINTENANCE OF HOSE MAY RESULT IN PREMATURE FAILURES, PROPERTY DAMAGE OR BODILY INJURY.
All hose have a finite life depending on the service conditions to which it is exposed. If a hose is subjected to conditions more severe than recommended limits then its life will be significantly reduced.
Variable factors, which can affect the actual service life, include:
WORKING PRESSURE: The fluid system pressure should not exceed the rated working pressure of the hose – usually one fourth of the hose maximum bursting pressure.
MINIMUM BURST PRESSURE: Burst pressures are reference values during in-house destructive tests, which are used to determine the strength of the hose and to establish design safety factors.
PRESSURE SURGES: Almost all fluid systems develop pressure surges which may exceed relief valve settings. Exposing the hose to surge pressures above the rated working pressure will shorten hose life and must be considered in selecting the proper hose. A surge, which may not be indicated on many commonly used pressure gauges, can be measured using specialized electronic equipment. Selecting a hose with a higher rated working pressure can increase the safety factor in systems where severe pressure surges occur.
TEMPERATURE RANGE: Hose should not be exposed to internal or external temperatures exceeding the recommended limits, as high heat conditions can cause an adverse effect on the hose by degrading the Elastomer and reducing fitting retention. Continuous use at near maximum temperatures can also cause hose damage whilst continuous use at maximum temperatures together with maximum pressures should be avoided.
FLUID COMPATIBILITY: The inner tube of the hose must be fluid compatible.
HOSE SIZE: The hose size must be capable of handling the required flow volume. Using the smaller than required diameter of hose for a given volume of flow would result in excessive fluid turbulence, pressure drop, heat generation and tube damage.
HOSE LENGTH AND ROUTING: Select the correct length of hose taking into account vibrations, flexing and hose routing. To protect and guide hose to minimize risk of damage use clamps, bends, adapters,protective sleeves wherever required to prevent excessive flexing, pulling, kinking, whipping and contracting or corrosives.
MINIMUM BEND RADIUS : Do not bend or flex hose beyond the specified parameter as this would put excessive stress on the reinforcement and severely reduce the ability of the hose to withstand pressure.
HOSE INSPECTION : All hoses in service should be frequently checked for leakage, kinking, corrosion, abrasion or any other signs of wear and damage. Any hose worn or damaged must be removed from service and replaced immediately.
ENVIRONMENT: hoses are more resistant to certain degradation, e.g. ultraviolet, light, ozone and many hydraulic fluids. Nevertheless due regard must be given to the working environment and the selection of hose best suited to operating conditions.