A hydraulic hose is specifically designed to convey hydraulic fluid to or among hydraulic components, valves, actuators, and tools. It is typically flexible, often reinforced, and usually constructed with several layers of reinforcement since hydraulic systems frequently operate at high or very high pressures. Hydraulic hose is used in a variety of industrial hydraulic systems. Dimensions, performance specifications, construction options, and features are important parameters to consider when searching for hydraulic hose.
Important dimensions for the selection of hydraulic hose include the inside diameter, outside diameter, and minimum bend radius. Hydraulic hose sizes are denoted by the inside and outside diameter of the hose. The inside diameter refers to the inside of the hose or liner. The outside diameter is often a nominal specification for hoses of corrugated or pleated construction. Minimum bend radius is based on a combination of acceptable hose cross-section deformation and mechanical bending limit of any reinforcement.
Construction options for hydraulic hose include reinforced, coiled, corrugated, or convoluted. Reinforced hose is constructed with some element of reinforcement—styles include textile braid, wire braid, wire helix, and other designs in many ply or layer configurations. Coiled hose is coiled for flexibility and elasticity. This feature often makes it expandable and easy to store. Corrugated hose contains corrugations, pleats, or spiral convolutions to increase flexibility and capacity for compression and elongation. Multi-element hydraulic hoses are constructed of more than one hose formed or adhered together in a flat, ribbon, or bundled configuration. Additional features to consider include integral end connections, anti-static, lay flat, crush-proof, flame-resistant, and explosion-proof.
In addition, material considerations include the type of fluid being conveyed and its concentration as well as substances that may attack the hose cover. Hose selection must ensure compatibility if it is to convey special oils or chemicals. The same holds for hose exposed to harsh environments. Substances such as UV light, ozone, saltwater, chemicals, and pollutants can cause degradation and premature failure. For in-depth fluid compatibility data, consult the manufacturer.
While hydraulic hose is usually constructed of multiple materials, the most commonly use primary materials include elastomers, fluoropolymers and silicone, thermoplastics, metal, and composite or laminated structures. Elastomeric or rubber hydraulic hose are often selected for their flexibility. Fluoropolymer hose offer good flex life, superior chemical and corrosion resistance, and can handle high temperatures. Thermoplastic hydraulic hose offer tight minimum bed radii and excellent kink resistance. Metal hoses can handle high temperature flow materials and often can handle very high pressures. They can be either stiff or flexible.
Flexible hoses are easier to route and install, compared with rigid tubing and pipe. They lessen vibration and noise, dampen pressure surges, and permit movement between parts. In addition, customer increasing demands for higher productivity, efficiency, and environmental compatibility are forcing hose manufacturers to improve product integrity—hoses now withstand higher pressures, extreme heat and cold, and accommodate a range of fluids including today’s “green” variants.
Most hoses are manufactured to SAE J517 or European Norm (EN) Standards, the latter based on earlier DIN German standards. These standards predominate in the Americas, Europe, and Australia. Both are also used throughout Asia, though that market is slowly gravitating toward EN specifications primarily because EN-rated hose has a higher pressure rating compared with similar-sized SAE hose. This gives greater safety factors should an application not need the highest working pressure.