Product Comparison – Semi-Rigid Tubing
Semi-rigid refers to a style of tubing that is stiff yet has some flexibility. It's not hard like metal tubing, but it's not as soft as polyurethane or PVC tubing. Materials include certain formulations of nylon, polyethylene, and polypropylene.
Most semi-rigid tubing is extruded from thermoplastic resin. The resin (sometimes called compound) is supplied in pelletized form and is melted before being shaped into tubing by extrusion equipment. Thermoplastic materials will repeatedly soften when heated and harden when cooled. Each of the three semi-rigid materials noted has its own benefits in tubing form.
Nylon has been recognized as a rugged engineering plastic since its development by E. I. DuPont in the 1930s. Aimed as a substitute for metal, its light weight and corrosion and abrasion resistance have made it a popular design choice. Nylon tubing has an exceptional elastic memory, making it well suited for retractable coils. It offers very low moisture absorption and is resistant to a variety of solvents, alkalis, petroleum products, and fungi. Applications include compressed air, coolant lines, dispensing equipment, grease lines, instrumentation, and paint supply.
Polyethylene, another engineered plastic, offers a high degree of inertness. This makes it applicable for markets such as food and beverage, laboratories, and chemical processing where leaching or permeability would present risks. Made from non-toxic ingredients that conform to FDA standards, the tubing also offers good dielectric properties. Polyethylene is available in several densities, although not all are extruded into tubing. High density polyethylene, or HDPE, is often used for food packaging and plastic bags and is recognized by the recycle symbol containing the number "2." Other polyethylene densities include medium, low, and linear low.
Polypropylene is the lightest of all thermoplastics available today. It offers excellent dimensional stability and electrical properties, good surface hardness and chemical resistance, and, like nylon, very low moisture absorption. Polypropylene tubing has a high strength-to-weight ratio, low surface friction, and excellent resistance to corrosion. It is harder than nylon and polyethylene. Polypropylene tubing is used in compressed air, environmental monitoring, food and beverage, potable water supply, refrigeration, and semiconductor manufacturing applications.
Nylon, polyethylene, and polypropylene have similarities as well. All accept coloration and are lightweight yet durable. In tubing form the three materials are flexible but may eventually kink if bent beyond a certain point. They all work very well with push-to-connect fittings, such as NewAge's Newloc® fittings. This style allows for a smooth flow of fluid or air, as the fitting's design and attachment method does not affect the interior of the tubing.
The following chart illustrates the materials' physical property differences.
Click here to view NewAge Industries' Nylotube® nylon-12 tubing, Zelite polyethylene tubing, or Prolite® polypropylene tubing.
If you need help determining which material is best suited for your application, be sure to contact a Fluid Transfer Specialist®.
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