Hoses and tubes can be made from a wide variety of materials, or multiple materials, making them able to be implemented throughout all industries. One of the most important criteria for the hose material, is the chemical resistance to the media that will be flowing through it. For common materials, you can see our chemical resistance chart to know if it will work for you. In this article, we will discuss the common material options and there is an material overview table at the end.
PU is the most common pneumatic tubing material as it has very good kink and abrasion resistance while being durable. It is typically rated for working pressures of 10 bar and higher. It also has good elastic memory, making it well suited for coiled, portable, and self-storing hose applications.
Nylon is a harder plastic than PU and is light, robust, dimensionally stable, and has excellent chemical resistance. It is less flexible than PU, but still has a good bend radius making it suitable for air distribution and applications with straight lines. For a standard 4x2 tube, it can handle up to 44 bar and temperatures up to 100°C. Nylon has good flexural-fatigue resistance and a low moisture absorption rate.
PP is very light and can even float on water. It has a very good chemical resistance to media like chlorinated water and acids. It has good surface hardness, dimensional stability, and electrical properties making it resistant against environmental stress cracking. It can handle higher temperatures and pressures when compared to PU.
Flexible PVC is often used for food-grade applications and is also a cost-effective solution. It is more flexible than PE and Nylon, but loses some durability compared to PU. PVC has a very good chemical resistance to media like chlorinated water and acids. It is also clear, making it suitable for applications that demand a visual flow indication.
PTFE is a very versatile hose material due to it’s outstanding chemical resistance making it almost chemically inert. It typically has a large temperature range of -196°C up to 260°C and is a dielectric (strong insulator) making it suitable for applications sensitive to static electricity.
PFA is a fluoropolymer like PTFE, making it very versatile due to it’s chemical resistance and being a dielectric. The main difference between PFA and PTFE is that PFA is melt-processed.
PE is a harder plastic compared to PU and its characteristics are similar to those of Nylon. PE is light, floats on water, flexible, and is a relatively cost-effective solution. It is typically used for low-pressure pneumatic systems and for pneumatic controls. A variation of PE is HDPE, which is more rigid, has a higher pressure rating, and is more durable.
Common rubber materials are latex, nitrile rubber (NBR), and ethylene propylene diene monomer (EPDM). Rubbers (especially latex) are flexible and have good elastic memory. To see their chemical resistance, see our chart. Looking specifically at latex, it remains unaffected by repeated sterilizing with for example steam, ethylene oxide, or even gamma radiation. Another benefit of latex is the absence of plasticizers and fillers that could leach out and contaminate the media or harden the tube.
Silicone is often considered a rubber, but it is actually a hybrid between a plastic and a rubber. It has many properties of both. From a plastic standpoint, it is flexible, temperature and water resistance, clarity, and is moldable allowing it to be shaped, formed, softened, or hardened. However, silicone has better characteristics than most plastics due to its chemical resistance, higher temperature rating, durability, and weather resistance.
Typically, hoses/tubes are considered ‘monolayer’, meaning they consist of one single material. However, hoses and tubes can be constructed using several layers of materials in order to have their characteristics complement each other. This is called ‘structured’ or ‘reinforced’ hoses and tubes. For example, a flexible PVC hose can be reinforced with textile braiding or knitting around the inner layer of the hose to increase the pressure rating.
Basic reinforced hoses or tubes consist of three general layers:
The actual reinforcement and combination of these materials is typically done by:
|Temperature||-35 to +60°C||-60 to +100°C||-196 to +260°C||-10 to +95°C||-35 to +65°C||-10 to +40°C|
|Vacuum||Tubes less than 8 mm ID||Wire reinforced||Wire reinforced or PP braided||Wire reinforced||Wire reinforced||Wire reinforced|
|Bending radius for 4x2 tube (mm)||10 mm||15 mm||20 mm||15 mm||Less flexible than PU||20 mm|
|Main application||Pneumatics||Compressed air, compressed air brake, hydraulic and fuel lines||Very aggressive media with extreme temperatures||Industrial processing||Food, beverage and drinking water. Garden hoses||Food, beverage and drinking water. Chemical processing|
|Chemical compatibility||Resistant to aliphatic hydrocarbons and most lubricants. Ageing resistance in oxygen.||Excellent resistance against hydrocarbons, concentration of (in)organic solutions||Excellent resistance to aggressive media. Suitable for food industry||Excellent chemical resistance and good abrasion resistance and is a good thermal and electrical insulator||Good chemical resistance to for example solvents and alcohols, acids, alkalis and salts||Mostly resistant to acids, alkalis and salt solutions|
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