10
5.2 Calculating Minimum Required
Fall Clearance
5.2.1 FT-R in Overhead, Non-Leading Edge
Anchorage Application
The FT-R may be used may be used as a
standard 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 minimum required
fall clearance (MRFC) is calculated using four
metrics, measured from the walking-working
surface: SRD Deceleration Distance, D-Ring
Shift and Harness Stretch [1 ft (0.3m)], Safety
Factor [1.5 ft (0.5m)], and Swing Fall. Chart 1
below is calculated using the performance data
of the SRD and includes all four metrics listed
previously to determine the MRFC.
X
-Set -Back
Distanc
e
Y
-Lateral O
ffset Dist
.
Z
- Minimum Required
Fall Clearance From
Working Surface
20.5
28.0
X
-SRD Anchorage Height
Above Dorsal D-ring
Z
- Minimum Required
Fall Clearance From
Working Surface
Y
- Lateral
Offset Distance
Figure 4
Using Chart 1 to Calculate Minimum
Required Fall Clearance for the FT-R
2 foot (0.6 m) increments along the Y-Axis represent
the Lateral Offset Distance the user is working away
from being directly under the SRD
5 foot (1.5 m) increments up the X-Axis represent the
SRD Anchorage Height above the user’s Dorsal D-Ring
Example:
If the user needs to work 10 feet (3.1 m) away from directly under the SRD, the SRD needs to be anchored at least
15 feet (4.6 m) above the user’s Dorsal D-Ring. Minimum required fall clearance is 9.5 feet (2.9 m) at maximum
allowable swing fall.
Example:
If the only suitable Anchorage for the SRD is at D-Ring height [0.0 feet (0.0 m)] above the user’s Dorsal D-Ring, the
maximum allowable work zone is 4 feet (1.3 m) away from the SRD. Minimum required fall clearance is 10.0 feet
(3.1m) at maximum allowable swing fall.
Key to Work Zone Areas:
= Allowable Use Area = Not Allowed Use Area
WORKING IN THIS AREA MAY RESULT IN SERIOUS INJURY OR DEATH
