Table of Contents
Advertisement
Available languages
Available languages
3.7
FALL CLEARANCE FOR SELF-RETRACTING DEVICES: Fall clearance is the measure of distance between a user and
the next obstruction below them. Required Fall Clearance (FC) is the amount of fall clearance needed to safely arrest the
user during a fall event. Fall clearance is always measured from the top of the working platform to the top of the next
obstruction below. To determine Required Fall Clearance for Self-Retracting Devices, refer to the following sections:
A. SETBACK DISTANCE: When calculating fall clearance with an SRD, 3M Fall Protection defines two different application
types based on the physical set-up of the system. See Figure 11 for an illustration of Setback Distance (X) and HLL
System Height (H). The application type determines the correct fall clearance chart to use.
SMALL SYSTEM SETBACK
Applies when:
•
Setback Distance (X) is less than the Retracted
Length (R) of the SRD.
- OR -
•
The System Height (H) is greater than or equal to
the Setback Distance (X).
See Section 3.7.B for more information. See Figure 9 for
Required Fall Clearance.
B. SMALL SYSTEM SETBACK: For Small System Setback applications, Required Fall Clearance (FC) is determined by
HLL System Height (H), HLL System Span (B), and the number of users connected to the HLL System. See Figure 9 for
reference.
•
SRDs should have a retracted length of 2.0 ft. (0.61 m) or less. For SRDs with a retracted length greater than
2.0 ft. (0.61 m), the difference in retracted length must be subtracted from the measured HLL System Height (H)
before selecting the proper height range.
Example - For an SRD with a retracted length of 5 ft. (1.5 m) and an HLL System Height of 7 ft. (2.1 m):
1.
Difference in retracted length of the SRD = 5 ft. (1.5 m) - 2 ft. (0.61 m) = 3 ft. (0.91 m)
2.
HLL System Height minus the difference in retracted length = 7 ft. (2.1 m) - 3 ft. (0.91 m) = 4 ft. (1.2 m)
3.
Use the number from Step 2 as your HLL System Height (H) when determining Required Fall Clearance (FC). In this
example, the user would use 4 ft. (1.2 m) for System Height (H) and select the [3 ft. - <5ft.] column in the Figure 9 charts.
To determine Required Fall Clearance (FC) using Figure 9 for SRDs:
1.
Select the chart that matches your number of users. Ensure the combined weight of each user (including
clothing, tools, etc.) does not exceed the maximum capacity listed.
2.
Find the column in the chart that matches your System Height (H).
3.
Find the row in the column to the far left that matches your System Span (B).
4.
Find the corresponding Required Fall Clearance (FC) where the column for your System Height (H) and the row
for your System Span (B) intersect.
C. LARGE SYSTEM SETBACK: For Large System Setback applications, Required Fall Clearance (FC) is determined by HLL
System Span (B) and the number of users connected to the HLL System. See Figure 10 for reference.
The following guidelines must be observed for Large System Setback applications:
•
SRDs used with the HLL System must be rated for tie-off at knee-level or below.
•
The Setback Distance (X) of the system must be greater than or equal to minimum requirements. Minimum
Setback Distance is listed in the table below for each available System Span (B). If you are unable to meet
minimum requirements, then your HLL System must be limited to one user per span.
System Span (B)
≤ 10 ft. (3.05 m)
≤ 20 ft. (6.10 m)
≤ 30 ft. (9.14 m)
To determine Required Fall Clearance (FC) using Figure 10 for SRDs:
1.
Find the Minimum Setback Distance for your system. Minimum Setback Distance is determined by HLL System
Span (B) and is listed in the table above. If your Setback Distance (X) does not meet minimum requirements,
then the HLL System must be limited to one user per span.
2.
Select the table column that matches your number of users. Ensure the combined weight of each user
(including clothing, tools, etc.) does not exceed the maximum capacity listed.
3.
Find the row in the column to the far left that matches your System Span (B).
4.
Find the corresponding Required Fall Clearance (FC) where the column for your number of users and the row for
your System Span (B) intersect.
Minimum Setback Distance
4 ft. 0 in. (1.22 m)
5 ft. 6 in. (1.68 m)
7 ft. 2 in. (2.18 m)
10
LARGE SYSTEM SETBACK
Applies when:
•
Setback Distance (X) is greater than or equal to the
Retracted Length (R) of the SRD.
- AND -
•
The System Height (H) is less than the Setback
Distance (X).
See Section 3.7.C for more information. See Figure 10
for Required Fall Clearance.
System Span (B)
Minimum Setback Distance
≤ 40 ft. (12.19 m)
≤ 50 ft. (15.24 m)
≤ 60 ft. (18.29 m)
8 ft. 11 in. (2.72 m)
10 ft. 8 in. (3.25 m)
12 ft. 5 in. (3.78 m)
Advertisement
Table of Contents
