Robin Daughtry is the Director of Marketing with Cross Company and is broadly familiar with solutions offered from the Automation, Instrumentation, Hydraulics, and Integrated Systems Groups.
We hear this question a lot and there is no simple answer....however there are several signs that maintenance personnel can look for to determine when it's time for preventive hose assembly replacement.
According to the Society of Automotive Engineers (SAE), the shelf life of bulk rubber hose is ten years from the manufacturing date - don't put old rubber hose assemblies on your equipment. The manufacturing date is on the lay-line so be sure to check it before using it.
Purchasing a new hose assembly is usually a lot less expensive than the cost of clean up after an old hose breaks and probably will save potential down time, damage to system components and perhaps even avoid potential injury.
Follow a Preventive Schedule - for most applications, a simple visual inspection once a month and preventive replacement of hoses every year or two is adequate. Eighty percent of hose failures are attributable to external damage through pulling, crushing, kinking or abrasion of the hose. Plus keep a log of the hose replacements (especially ones caused from hose failure). Use this log to to estimate how long your hoses last in your application, but never stop your regular visual inspection.
Important - never touch pressurized hoses with your hands (not eve with gloves on). If you are looking for a pinhole leak, use a piece of cardboard or wood to locate it. NEVER run your hand over the hose to find it - hydraulic injuries are very serious and can result in amputation or even death.