Selecting the right kind of cable carrier for an application starts with a few simple guidelines. The most important points to consider are the specifics of the application. These include the length of travel, the number of cables or hoses, the size and weight of the cables, the required speed and acceleration and environmental factors such as exposure to any debris, excessive heat or chemicals. Knowing the weight of the cables also ensures that the carrier won’t fail by snapping in two.
Cable carrier styles can be either open or closed. Open varieties allow for easy access to the cables and visible access as well, whereas closed carriers seal off the cables from the environment to protect from environmental contaminants such as metal filings.
Environmental conditions play a large part in selecting a cable carrier. If the application is in a dirty or contaminated area, an enclosed carrier is the best choice. An open carrier is lightweight and makes inspecting and replacing cables easier.
One of the most crucial factors is choosing the right bend radius for the cable carrier. Bend radius is measured from the center of the curve loop to the center of the pivot pin on the side link. A larger bend radius means less stress on the cable and a longer service life. It’s important for the bend radius, with the exception of applications with space restrictions, to be larger than the recommended minimum bend radius of the cables and media that make up the fill package.
All cable carriers have a predetermined radius stopping point on each link. When a number of links are assembled, these stopping points restrict the carrier from fully pivoting and form a curve loop, or minimum bend radius.
All cable carriers have multiple bending radii to choose from and every manufacturer suggests a minimum bend radius. The bending radius chosen for the cable carrier will depend on the cable or hose with the largest diameter. Selecting a considerably larger bend radius than required for the fill package will extend the lifespan of the cables and hoses.
General rules for selecting the bend radius
- Don’t exceed the manufacturer’s suggested minimum bend radius; however, using the largest bend radius possible is optimal.
- If you don’t know the recommended minimum bend radius of the cables in the fill package, follow these guidelines from NFPA 79 2007: “Cables with flexible properties subject to movement shall be supported in such a way that there is neither mechanical strain on the connection points nor any sharp flexing. When this is achieved by the use of a loop, it shall provide the cable with a bending radius of at least 10 times the diameter of the cable.”
- The larger the bend radius, the less stress is put on the cables and hoses, which will ensure longer service life.
- Keep in mind that the minimum bending radius is partly based on a temperature range for flexing. Special consideration is needed when the environment reaches or exceeds the temperature rating for the cable. This is especially true for low-temperature applications using thermoplastic cables, which tend to stiffen when exposed to the cold. Stiff cables can raise the radius of the cable carrier and lead to mechanical failures. Best practice is to use a cable with a low-temperature rated PUR or TPE jacket and/or consult the manufacturer for bend radius recommendations.
- In applications with severe space restrictions, the bend radius of the cable carrier may need to be smaller than the recommended minimum bend radius for the fill package. This is not ideal, but if it cannot be avoided, use cables specially designed for low bend radius installations or consult your cable carrier manufacturer for the best solution.