A
0.7 m
(21/2 ft)
Deceleration Distance
Maximum allowable length of cable or web that
may payout from the SRD once deceleration of the
user has begun and after a fall event occurs. For
work in low clearance areas, see Table 1B for Typical
Performance
B
0.5 m
(11/2 ft)
Dorsal D-Ring Shift and FBH Stretch
Combined amount of Dorsal D-ring up-shift and har-
ness webbing elongation during entire fall event
C
0.5 m
(11/2 ft)
Safety Factor
Added length to account for other factors such as an
improperly adjusted harness, actual worker height
or worker weight
D
1.7 m
(51/2 ft)
Sub Total- Minimum Required Fall Clearance
for direct overhead use of SRD with No Swing Fall;
sum of A, B and C only
E
____ m
*Additional Fall Clearance Calculation
due to Swing Fall (using Chart 1)
F
____ m
Total Required Fall Clearance
Including sub-total D and Swing Fall E (from Chart 1)
1. Overhead Anchorage 2. Walking/Working Surface
3. Nearest Lower Level or Obstruction
A Anchorage
B Self-Retracting Lifeline
C Walking/Working Surface
D Swing Fall Impact after fall event
E Next Lower Level or Obstruction
Figure 4 - Calculating Required Fall Clearance: Overhead Anchorage
Figure 5 - Swing Fall Hazards: Overhead
CMSRD15 Rev A
022120
7
5.4 Minimum Required Fall Clearance Calculation
DuraTech SRD in an overhead condition, in which the SRD is installed anywhere in the allowable attachment area, which ranges from
directly above the user to level with the FBH D-ring, as shown in Figure 4. The overhead condition MRFC has six metrics, labeled A – F,
measured from the walking/working surface.
A = SRD Deceleration Distance
B = D-Ring Shift and Harness Stretch
C = Safety Factor
D = Sub Total- Minimum Required Fall Clearance
E = *Additional Fall Clearance Calculation Due To Swing Fall
F = Total Required Fall Clearance
The MRFC for an overhead anchorage, with no swing fall condition, is calculated as A+B+C=D. The user must be aware that if a swing fall
hazard exists, as shown in Figure 5, additional steps are required. Use Chart 1 on the following page to determine the amount of swing
fall, and place that value in E. Add the E value to the D value to determine the total MRFC.
