P = Pressure: Be sure to account for any spikes the system may incur. Published working pressures must be equal to or greater than the system pressure. Never try to exceed the 4:1 safety factor because doing so will shorten hose life.
E = Ends or fittings: A general rule of thumb is to connect a hose with the least amount of connections possible. Refer to the manufacturer's catalog or consult a specialist to determine the correct fittings. Several manufacturers, including Goodyear and Gates, offer software programs to help guide you through the hose/coupling selection process.
D = Delivery (volume and velocity): If the same inside diameter of the original hose is used, you can assume the system is properly sized to efficiently transport the fluid. However, if you have a new system, or if you have altered the old one, you will need a new hose size. Consult the hose manufacturer's catalog for recommended flow rates.
Safety is of utmost concern when it comes to hydraulic systems, including when selecting, maintaining and replacing hoses.
"Those hydraulic hoses are going to a cylinder that distributes power," says Watts. "If a hose fails when someone is using a bucket on a loader, the cylinder can make the bucket close or it can dump its contents unexpectedly. If it's a high-lift application, safety is of greater concern."
With that in mind, these experts outline the following tips for minimizing hydraulic hose failures:
1. Utilize one source, one system. Purchase all parts — hoses, couplings and crimpers — from the same company. "As manufacturers, we make our hoses with some differences that make them incompatible with someone else's coupling," notes Douglass. "It is a very dangerous practice to mix and match hoses and couplings from different manufacturers."
2. Learn to identify potential hazards. Look for cracks and abrasions in the cover. "The cover protects the reinforcements (wire or fabric) from weather and environmental hazards such as rocks," says Kemper. "If the wire or fabric is exposed, water and debris can adversely affect the reinforcement by either rusting the wire or, in the case of fabric, allowing water to wick into the system and get behind the coupling where it can cause damage."
Also check to see if the hose is twisted. Look for any seepage in the area of the coupling or on the hose and any bubbling on the cover.
In extremely abrasive situations or in areas where you simply can't get away from abrasion points, consider hoses with special coverings, such as Gates XtraTuff and MegaTuff hose covers, which can offer from 25 to 300 times the abrasion-resistance of a standard hose. Goodyear also offers its Armorcoat hose coverings for these situations.
Be aware that if you utilize nylon sleeves for abrasion resistance, you can still see abrasion beneath the cover and, in some cases, the sleeve may actually cause the abrasion.
3. Keep good maintenance records. "The best predictability of life is maintenance records," says Watts. Goodyear offers a software system that can track hose replacement to provide data on when to replace hoses when no cracks, abrasions, etc., exist.
4. Develop and adhere to a preventive maintenance schedule. Inspect the hydraulic assembly on a regular basis based on the application. Hoses used on a boom arm, in a rough environment with a lot of dirt and sand and/or in a sunny area should be checked frequently. If you see a hose starting to crack, replace it before it fails in the field. "Downtime on the jobsite is much more costly than maintenance time in the shop," says Watts. "Make those inspections an integral part of your routine."
5. Install the assembly correctly. Keep the assembly capped until you're ready to use it. When installing fittings, crimp them correctly for the diameter of the hoses.
If an elbow is used, be aware of the orientation for attaching it to the equipment. If there is a swivel on one end, don't twist it during installation. Consult a specialist to determine the best routing. "Installing it according to its original route may not be the best way to reinstall it," says Watts. Reinstall all the brackets to ensure adequate support.