Page 18 - Rappelling

to a high impact force, but it is a great rope for Nfpa static rope testiNg
applications where stretch is not required. In the United States static rope and low-stretch
ropes are tested by a third party, such as Underwrit-
low-stretch ropes
ers Laboratories (UL), to meet guidelines set by
The Cordage Institute defines low-stretch as a rope the National Fire Protection Agency (NFPA) and
with an elongation between 6 and 10 percent at 10 the Cordage Institute (CI), which set US standards
percent of the rope’s MBS. Since a low-stretch rope for “life safety ropes” used by rescue teams, police
has relatively little stretch (usually 3 to 4 percent SWAT teams, fire departments, and vertical rope
under body weight) compared to a dynamic rope, it access professionals. A life safety rope is defined as
is a great choice if you’re using it just for rappelling. a rope on which your life (or someone else’s life)
Low-stretch ropes are also a good choice for verti- depends on, possibly time and time again, as in the
cal rope access, toproped rock climbing, rigging, and case of rescue professionals. The NFPA 1983 rope
applications where some stretch is desired to add an performance standard (modified in 2006) defines
element of shock absorption to the rope system. three specific categories for life safety ropes: per-
sonal escape, light use, and general use.
ce eN 1891
On both static and low-stretch ropes manufac- Personal Escape Ropes
tured in Europe, the CE label indicates the rope For NFPA certification a personal escape rope must
has passed testing in accordance with EN 1891 be designated for onetime use only, with a diameter
(European Norm). There are two types of EN 1891 of between 7.5 and 9.5mm when under load, with
certifications: Type A and Type B. To receive an EN elongation between 1 and 10 percent at 10 percent
1891 Type A rating, the rope must have a minimum of MBS, and an MBS of 13.5 kN.
diameter of 10mm and be able to hold at least 22
kN (4,495 lbs.). A Type A rope must also be tested Light Use Ropes
to withstand five factor 1 falls with a weight of 100 For light use NFPA certification, the rope must be
kg (220 lbs.) on the end of the rope. The fall factor between ⁄8 inch (9.5mm) and ⁄2 inch (12.5mm)
3
1
is the total distance of the fall divided by the length diameter and have an MBS of at least 20 kN (4,496
of the rope that comes into play during the fall. lbs.), with elongation between 1 and 10 percent at
What is a fall factor 1? Let’s say you’re standing on 10 percent of MBS (450 lbs.).
a bridge. You are tied to one end of a 200-foot rope,
and the other end is attached to the bridge at the General Use Ropes
level where you’re standing. You step off the bridge For general use NFPA certification, the rope must
and fall the length of the rope. You’ve fallen 200 feet have a diameter of between ⁄16 inch (11mm) and ⁄8
5
7
until the rope comes tight. Total distance of the fall inch (16mm), with an MBS of 40 kN (8,992 lbs.)
(200 feet) divided by the length of the rope to the and elongation between 1 and 10 percent at 10 per-
anchor (200 feet) equals a fall factor of 1. cent of MBS (899 lbs.).
An EN 1891 Type B–certified rope is between NFPA-certified ropes are tested for both a static
8 and 9.9mm in diameter and must be able to hold strength (tensile strength) rating and an SWL rating.
at least 18 kN (4,045 lbs.) and withstand five factor The NFPA (and OSHA) standard for SWL is ⁄10 of
1
1 falls with a weight of 80 kg (176 lbs.) on the end the MBS.
of the rope.

Equipment 7

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