Rope Strength Section V' of Ropes

1
Rope Strength Section V. of Ropes Knots

• Patricia A. McIntosh
• Submitted in partial completion for
• NFPA 1041 Instructor I

2
Objectives

• Define terms related to strength of life safety
  ropes.
• Describe the ratings of ropes used in fire and
  rescue service.

3
References

• NFPA 1983 - Standard on Fire Service Life Safety
  Rope and System Components
• National Fire Protection Association, ed.
  Fundamentals of Fire Fighter Skills. 2nd ed.
  Jones Bartlett, 2008

4
Rope Strength Terms

• Rated Load
• The number of persons or weight for which a rope
  is rated.
• Minimum Breaking Strength
• The minimum pounds of force (lb/f) which can be
  exerted before breakage occurs.

5
Rope Strength Terms (2)

• Safety Factor
• The ratio of Minimum Breaking Strength to Rated
  Load.
• Minimum Breaking Strength Rated Load
• 3,000 300
• 10 1

6
Required Strength of Life Safety Ropes
Source NFPA 1983.
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Safety Factor

• Allows for Reductions due to
• Twists
• Knots
• Abrasions
• Others

8
Safety Factor (2)

• Shock Loading
• Falls
• Sudden changes in load
• Added strain on rope

9
Summary

• Terms
• Rated Load
• Minimum Breaking Strength
• Safety Factor
• Ratings
• Personal Escape
• Light Use Life Safety
• General Use Life Safety

10
Review

• NFPA ________ specifies the minimum strength
  requirements for life safety rope.
• Light Duty Life Safety Rope has a minimum
  breaking strength of ____ lbf.
• TRUE or FALSE Shock Loading refers to weight
  applied for extended periods of time.