|Tubing & Hose Buying Tips
#4: Flexibility & Kink Resistance
It can be challenging to make sure you’ve covered all the bases during the tubing and hose selection process. Have you considered all the elements involved with the application? Temperatures, chemicals, pressures, flexibility needs? In Tubing & Hose Buying Tips we’ll address common selection factors, one at a time, in each issue of extrusions.
Flexibility is a property that varies greatly depending on the type of plastic or rubber material and its construction. Factors that affect flexibility include durometer (softness or hardness), force-to-bend, size, wall thickness, reinforcement style, and temperature. Some plastic tubing and hose, like that made from softer-durometer PVC or polyurethane, is very flexible. Most rubber tubing such as silicone, latex, and Viton® is also flexible. Examples of harder durometer flexible plastic tubing include those made from nylon, fluoropolymers, polyethylene, and polypropylene. These are fairly stiff in their common straight tubing styles but are bendable. Customization such as coiling, convoluting, and corrugating can make them more flexible.
Some applications call for repeated flexing of the tubing or hose. Situations involving robotics or circumstances where the tubing is repeatedly moved require special consideration. The tubing or hose must be durable enough to withstand such movements. Instances where the tubing comes into contact with other equipment should be examined as well. Many materials offer abrasion resistance and are able to withstand repeated flexing and rubbing.
Closely related to flexibility concerns is kink resistance. If your application calls for the tubing or hose to bend around machinery, its resistance to kinking and collapsing upon itself must be considered. Sometimes a very flexible material silicone, for instance can address the issue. But if pressure and/or durability requirements will not allow the use of such a soft material, the hose’s construction can come into play. Braid or wire reinforcement can help to reduce the occurrence of kinking, as can products that are multi-layered. Stiff materials can also resist kinking provided that enough length is incorporated into the design.
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