WORKING LOAD LIMIT Working Load Limit (also known as Safe Working Load or Recommended Working Load) is defined as the maximum load that may routinely be applied to an assembly or component in straight tension. The other strength term is ultimate strength (or tensile strength). Ultimate Strength is the load at which a component or assembly will fail in a test. We have chosen to use the NFPA ratio of 15:1 for ropes and the American engineering standard of 10:1 for critical use hardware and auxiliary equipment. We realize that these ratios may exceed proposed standards, but have selected them because they best apply to the rescue community. We show the Working Load Limit (WLL) because the ultimate strength may change during the life of the product. Whereas, the WLL remains valid during the normal life of the product. For example, a 9,000 lbf. rope will lose strength as it is used. The WLL will remain 600 lbs. throughout the normal service life of the rope. Additionally, rescue products should be chosen and matched based upon their WLL. The item with the lowest WLL limits the system working load limit. Remember, a chain is only as strong as its weakest link.
Posted on: Wed, 26 Jun 2013 04:58:57 +0000
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