Hydraulic Hose-Back to the Basics
A hose may be defined as a flexible tube designed to carry fluids from one location to another.
A hydraulic hose then, is a high pressure hose made of synthetic rubber, Teflon, thermoplastic or even stainless steel, that typically carries pressurised fluids or gases in order to transmit force within a hydraulic system or machine. Thus, Hydraulic hoses play a major part in hydraulic systems.
Selection, manufacture, assembly, installation procedures are all very critical factors in ensuring optimum usage of hydraulic hoses.
Since hydraulic hoses come in a variety of design types and materials, selection of the right type of hose for an application depends on understanding and factoring several factors.
This article intends to explain just about everything a beginner in the industry needs to know, and also as a refresher for experienced hands too.
Hydraulic hoses are used as essential components of hydraulic systems for a variety of reasons but mainly due to its flexibility to bend around corners and tight spaces and due to the fact that they can be used to cover relatively long distances for transfer of fluid. Hydraulic hoses may have several layers of reinforcement to operate at very high pressures.
So what are hydraulic hoses made up of?
Modern Hydraulic Hoses are made up of a variety of materials but the most common material used even today are elastomers (rubber), thermoplastics, fluoropolymers like Teflon, silicone and metals like stainless steel. Composite and laminated materials are also used for hydraulic hoses. Elastomeric hoses are used for low to high pressure and preferred for their excellent flexibility. Fluoropolymer hoses are used for high temperature operations and provide durability and excellent chemical and corrosion resistance. Thermoplastic hoses have superior resistance to kinks and offer a tight minimum bend radius. Metal hoses like Stainless Steel Hoses can withstand extreme temperatures, high flow materials, and high pressure, with stiff or flexible options as the application demands.
The flexibility of hoses make them easier to install, route and replace and help in reducing noise and vibrations, dampen pressure surges besides allowing movement between the parts.
Construction of a Hydraulic Hose
A typical hydraulic hose consists of an inner tube to carry the medium, a reinforcement layer sandwiched between the inner tube and an external protective layer. Inner tubes are flexible and commonly composed of a compound mix of synthetic rubber, PTFE and thermoplastics mainly to provide compatibility with most fluids. The reinforcement layer has multiple sheaths which may be made of textile, spiral wound wire or braided wire while the outer layer is made to resist abrasion, external weather conditions and resist oil.
Hydraulic Hoses sometimes take the form of convoluted or corrugated or even coiled hoses. Coiled hoses are preferred for its elasticity and flexibility that makes easy to store, and expandable when in use. Corrugated hoses has pleats or convolutions that are spiral to increase flexibility and enhance its capacity for elongation or compression.
All hoses have a finite life. So to ensure hose longevity during its service period, choosing the right type and size for any particular application is of utmost importance.
To get the most out of your hose use the STAMPED method of selection and also make note of the following :-
- Avoid Flexing the hose below the rated minimum bend radius
- Do not twist, kink, pull or disturb the braiding on hose.
- Operate the hydraulic system within the pressure ratings for which the hose was selected for especially taking care to avoid exposing the hose to pressure surges above the maximum operating pressure.
- Importantly, if in doubt always consult with the manufacturer to ensure compatibility and other parameters.
Choosing the correct type of hose and grade after understanding the work conditions will go a long way in extending the working life of your hydraulic hoses.
Read more about hoses here on Wiki.