The Competent Person may find this data useful with planning anchorage location and calculating fall arrest loads and distances from the
walking/working level to the nearest obstruction or lower level. See Section 5.
NOTE:
Arrest distance is one part of the Minimum Required Fall Clearance (MRFC). The MRFC is determined by consideration of multiple
factors in fall protection. Attachment below the level of the FBH D-ring will require additional fall clearance. MRFC is discussed in
detail in Section 5.
4.7
PFAS Anchorage Strength:
An anchorage selected for PFAS must have a strength able to sustain a static load applied in the direction
permitted by the PFAS of at least:
a) Two times the maximum arrest force permitted when certification exists, or
b) 5,000 lbs. (22.2 kN) in the absence of certification.
MSRD20 Rev B
110421
7
Longest Arrest Distance
109” (2.8 m)
109” (2.8 m)
Largest Average Arrest Force
1,131 lbs (5.0 kN)
1,042 lbs (4.6 kN)
Largest Maximum Arrest Force
1,631 lbs (7.3 kN)
1,546 lbs (6.9 kN)
5’ (1.5 m) Setback
0’ Setback
Select an anchorage location carefully. Consider structural strength, obstructions in the fall path, and swing fall hazards. In certain
situations, the qualified person can determine that a given structure is able to withstand the applied MAF of the PFAS with a safety factor
of at least two, as required by OSHA.
4.5
Personal Fall Arrest System:
A PFAS is an assembly of components and subsystems used to arrest a person during a fall event. A PFAS
is typically composed of an anchorage and a FBH, with an energy absorbing connecting device, i.e., an SAL, an SRD, or a Fall Arrester
Connecting Subsystem (FACSS), connected to the dorsal D-ring of the FBH. PFAS components used in conjunction with this SRD should
comply with ANSI Z359 requirements and applicable OSHA regulations.
4.6
Average Arrest Force and Arrest Distance:
Table 1B provides test data on typical performance attributes of the three principal
parameters, Arrest Distance, Average Arrest Force and Maximum Arrest Force, listed by model number and class. Testing is conducted
under various environmental conditions; at ambient temperature, plus hot, cold, and in wet conditions. In manufacturer’s tests, worst
case performance attributes of the SRD, connected at foot-level (maximum of 5 feet below the dorsal D-ring) in a Leading Edge application
with 5’ (1.5m) of setback, or with 0’ setback, are:
A
Never connect two active components (snap hooks or carabiners) to each other.
B
Never connect two active components (snap hooks or carabiners) to a single D-ring at the same time.
C
Never connect in a way that would produce a condition of loading on the gate.
D
Never attach to a object in a manner whereby the gate (of the snap hook or carabiner) would be
prevented from fully closing and locking. Always guard against false connections by visually inspecting for closure and lock.
E
Never attach explicitly to a constituent subcomponent (webbing, cable or rope) unless specifically provided for by the manufacturer’s instructions for both
subcomponents (snap hook or carabiner and webbing, cable or rope).
F
Never attach in a manner where an element of the connector (gate or release lever) may become caught on the anchor thereby producing additional risk of
false engagement.
G
Never attach a spreader snap hook to two side/positioning D-rings in a manner whereby the D-rings will engage the gates; the gates on a spreader must
always be facing away from the D-rings during work positioning.
Figure 3 - Non-Compatible Connections
