Hose products need to handle high temperatures and environmental stress to prevent premature hose failure and safety risks. Thermoplastic hose offers a wide variety of added value over their rubber counterparts. Thermoplastic hose is built with a high level of contact strength between the layers of core, braid and jacket. This contact is generated because thermoplastic materials can be re-melted during the production process allowing for both a chemical and mechanical bond.
A process that makes the difference
Parker's unique bonding process creates projections on the outside of the core that extend up into the braid, while the jacket material is forced down into the braid from the outside. Each hose has specific dominant characteristics, such as increased abrasion resistance or consistent long lengths to reduce leak points. These hoses easily handle the high temperatures and environmental stress that break down rubber hoses, causing premature hose failure, unexpected safety risks and down time, as well as, lost revenue from clean up and on–site job repairs.
In the past, the majority of hoses were made from rubber but today, a thermoplastic hose may out live conventional rubber products for several reasons.
- Rubber hose can crack from low temperature embrittlement; therefore, it may not work well in freezers and cold weather.
- Thermoplastics are designed to handle low temperatures.
- Rubber may fatigue from the constant flexing motion experienced in many applications.
- Thermoplastic hose can have a fiber reinforcement bonded between the hose and the jacket designed to handle constant flexing, even at higher pressures.
In addition, these hoses offer good chemical/corrosion resistance and can be formed for easy routing or bonded together to create a single unit from multiple hoses.
Hose core tube
Thermoplastic hoses are designed with safety and cleanliness in mind. The erosion resistant core maintains long-term system cleanliness with mandrel free construction to ensure zero lubricant contamination. And with fiber reinforced thermoplastic hose, there's little to no contamination due cutting because they do not require a hose saw. While cleanliness is inherent in thermoplastic core tubes, some Parker hoses also maintain non-conductivity, keeping the operator safe from electric shock.
Hoses are extremely vulnerable to external damage once the jacket has been compromised. The jacket of a hose has one main job. It must protect the structural member of the system and the braided reinforcement. If it is cracked it allows the braid to be exposed to the environment, chemicals and abrasives that are harmful to its integrity. Unlike rubber, a thermoplastic jacket will not delaminate, which can lead to jacket failure and wire fatigue.
Most thermoplastic hoses feature a UV and ozone resistant cover which resists cracking and UV damage, thus extending the service life of the hose. Parker also produces specialty jackets, offering increased resistance to the elements and/or flexing, a variety of colors and laylines can be customized, enabling customers to color-code their systems and provide specific information on the hose itself.
Small inner diameter (ID)
Because thermoplastic hose/tube manufacturing does not require a mandrel for support of the core tube, hoses can be made to extremely small inner diameters such as 1.3mm/(.051"). Since rubber hoses require a mandrel, the inner diameter of rubber hoses typically stops at 4.8mm (3/16"). This is important in applications where only a small amount of fluid needs to be transferred. A smaller inside diameter also allows for a tighter bend radius. The bend radius is less than half of conventional SAE 100R1 & 100R2 hoses.
Compact outer diameter (OD)
The inherent strength of the thermoplastic materials used to make hose allows the use of less material when compared to rubber hose. The outer diameter of thermoplastic hose from Parflex and Polyflex can be 20% smaller than outer diameters on comparable rubber hose. This feature is very important on equipment where space is limited and many hoses must fit into a small area.
Long continuous lengths of hose
The manufacturing process of thermoplastic hose allows for long continuous lengths due to the material being “cured” on the line and a self-supporting core tube. Rubber hoses requires a secondary curing process and a mandrel to hold the core tube dimensions. The Parflex and Polyflex divisions of Parker Hannifin have made continuous lengths of 3200m in the past - important for off shore oil applications such as marine (umbilicals). For hose assembly locations, the long lengths mean less scrap, minimized leak points and fewer reel changeovers during production.
Weight (per foot)
Thermoplastic hoses, due to the material and construction, are up to 40% lighter than comparable rubber hoses. With Parker XDT products, low pressure rubber lines can be replaced with thermoplastic tubing that is 70% lighter.
Some Thermoplastic hoses can be thermally formed into specific shapes to suit unique customer application requirements, allowing for cleaner routing, reduced scrap and quicker installations. Formed hose is rigid but flexible, and can be stored in small boxes rather than wooden crates, reducing shipping costs and increasing floor space. Formed hose also maintains and preserve its shape once formed and can be routed throughout small, hard-to-reach areas, leading to fewer connecting points and eliminating the need for hose-tube combinations.
By installing one bonded hose element rather than multiple hoses, companies lower material cost, reduce installation time and lower the weight of the finished assembly. Bonded hoses eliminate the problem of tangling in multiple hose applications and eliminate the abrasion damage caused from hoses rubbing against each other. They also improve the management of the hose and increase the overall strength, eliminating some of the reasons hoses fail in the field. A bonded hose is particularly beneficial in lift truck, hydraulic crane and aerial lift applications. Parker Twin-Line hoses consists of two identical hoses permanently joined for the entire length of the hose, offering a compact system for easy installation and smooth operation. Multi-Line hoses consist of two to ten hoses (or a maximum width of 10”) in various combinations of sizes and types. Where needed, hoses can be separated to allow for routing.
Many thermoplastic materials are inherently abrasion resistant. In fact, thermoplastics are often added to rubber hose covers to increase most rubber hose manufacturers add thermoplastic to hose covers to increase the abrasion resistances of their hoses. Parker hoses come in a variety of styles, with some offering 5x the abrasion resistance of any rubber hoses that are touted as abrasion resistant.
The pictures to the left compare the contamination levels, after manufacturing, of a thermoplastic hose and a rubber hose. As seen in the pictures, the manufacturing of thermoplastic hose produces far less contamination than rubber equivalents. In many cases, the assembly of rubber hose will require cleaning of the hose prior to production use.
Through the use of various hose reinforcement methods, Parker can manufacture hoses that can endure 4000bar (58,000psi) working pressures.
Through the use of various thermoplastics, the permeation resistance (ingression and egression) can be far greater than rubber. As shown in the chart, thermoplastic has superior permeation resistance against gases like CO2, Oxygen, and Nitrogen in comparison to rubber.
Under optimal storage conditions, thermoplastic hose and tubing products should have unlimited storage life prior to initial usage. Per SAE J517, Rubber Hose is acceptable for 10 years if stored under optimal conditions.
Thermoplastic hoses with specific reinforcement have been shown to reduce noise on machines. This is important to operator comfort and environmental noise pollution.
For more information about how thermoplastic tubing can meet your application needs, visit Parker.com or contact:
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