Prussic Knot Advantage:
Reduced Margin/Length of Fall:
A
The advantage of using a Prussic Knot with a SAS engineered system results in a
significaent reduction in the legth of fall plan of approx. 26%. This is accomplished
by reducing two primary factors: 1) Energy absorber deployment length (E) is
reduced by 6” (150mm). 2) Rope grab deceleration (F) is reduced 42” (1.06m). Note
D-Ring
postion above
Leading Edge
: A system specified for heavier workers will require a greater margin (G) in the
length of fall plan.
SAS Engineered System:
Using 100% SAS, PPE provides a solution for free fall hazards commonly present on
single story structures where the eave line may be less then 15ft. (4.6m) above
ground.
AvrsP Max user wt. 220lb (100kg)
Sample Length
of Fall Plan
ANSI
2007.1
Prussic
Knot
Length
Reduced
B
Excess
Lifeline Slack
C=Maximum
6ft. (1.8m)
free fall
A= D-Ring position at
(C)
leading edge 48”
72”
B=(A+C=B)
Lifeline slack 24”
D= Harness/Lifeline
12”
Stretch
E=Absorber ■
6”
42”
36”
Deployment
F=Rope Grab
42”
54”
12”
Deceleration
132”
180”
G=Length of Fall from
leading edge to ground 15ft. (4.6m) 11ft. (3.3m)
Length of fall reduced - - - - - - - - - - - - - - - - - - - - - 4ft. (1.2m )
C
Free Fall
6ft. (1.8m)
(A-C)=B
G
Notes: ■ I6061-I6061k absorber deployment based on SAS performance tests
Energy Absorber Deployment Lengths: ANSI
2007/2009.
A *rigid test mass to simulate the weight of a heavier live person. For
example: ANSI 2007: 220lb=310lb. CSA E-4: 220lb=254lb. CSA E-6:
360lb=386lb. The ANSI 2009 revised engineering increased the test
mass to 282lb and absorber deployment length from 42” to 48”.
Therefore, energy absorbers built to ANSI 2007 specifications should
not be specified for 310lb workers. SAS has voluntarily specified
lower user weights than ANSI or CSA standards allow.
*The human form will absorb more energy than a rigid structure.
Performance Standards for ANSI 2007/CSA E-4
Energy Absorbers:
ANSI 2009 allows peak force values of up to 1800lb using peak averaging to demosrtate forces of 900lb or less. CSA E-4 does not allow
averaging of an peak calues greater than 900lb. All SAS energy
aborbers are tested to the maximum ANSI/CSA performance values
and marked accordingly even though labels specification for use are
less than the published standard.
Worker weight ranges between 100-340lb are provided by specifying the use of either E-4 or E-6 energy absorbers, eliminating the for
SAS to produce ANSI 2009 6ff FF models.
Margin required
from Leading
Edgeto ground
Total Length
of Fall
D
Harness/
Lifeline
Stretch
E
Absober
Deployment
F
Rope Grab
Deceleration
Ground, lower level, or hazard below
SAS00057.PrussicKnotAdvantage.01112013