Table des Matières
Publicité
Les langues disponibles
Les langues disponibles
5.1. Plan the Personal Fall Arrest System (PFAS): Examine the work area and take action to address hazards. Falls are a serious hazard
when working at height. Training and equipment are the tools of fall hazard management. There are several closely related facets of fall
hazard management with a PFAS;
•
Anchorage
•
Minimum Required Fall Clearance (MRFC)
•
Swing Fall and Expanded Work Zone
•
Overhead (above the FBH D-ring) Anchorage
•
Non-overhead Anchorage
•
Rescue
5.2 Anchorage: Select a suitable anchor point. See paragraph 4.4. Determine the anchor point location relative to the height of the user's
FBH D-ring. Also, consider how many feet of lateral travel the work will require. To avoid an unintended disengagement of connectors,
use only compatible connectors when connecting to the anchorage. Ensure all connectors close and lock securely.
5.3 Minimum Required Fall Clearance: The MRFC is the minimum distance a user needs between himself and the nearest obstruction (or
ground) below the walking/working surface to avoid serious injury or death in case of a fall event. The user of this equipment must
determine the MRFC for units discussed in this manual to ensure adequate clearance exists in the fall path. Variables discussed in this
manual include the height of the anchor point relative to the user's FBH D-ring, i.e., overhead or non-overhead anchorage condition, plus
swing fall, and how an expanded work zone affects these variables.
5.4 Overhead (Above the D-Ring) Anchorage Condition: In an overhead anchorage condition, the SRD is installed anywhere in the
allowable attachment area, which ranges from directly above the user to as low as the level of the FBH D-ring, as shown in Figure 6. The
overhead condition MRFC has three metrics, labeled A, B, and C, measured from the walking/working surface. The sum total of these
metrics, labeled D, is the sub-total MRFC.
A = SRD deceleration distance
B = D-ring shift and harness stretch
C = Safety factor
D = Sub-Total MFRC
E = Additional Fall Clearance Calculation Due to Swing Fall (using Chart 1)
F = Total Required Fall Clearance
The MRFC for an overhead anchorage is calculated as A+B+C=D.
CMSRD14 Rev A
Figure 6 - Calculating Minimum Required Fall Clearance - Overhead Anchorage
Deceleration Distance
Maximum allowable length of cable or web that
1.2 m
may payout from the SRD once deceleration of the
A
(4 ft)
user has begun and after a fall event occurs. For
work in low clearance areas, see Table 1B for Typical
Performance
Dorsal D-Ring Shift and FBH Stretch
0.5 m
B
Combined amount of Dorsal D-ring up-shift and har-
(11/2 ft)
ness webbing elongation during entire fall event
Safety Factor
0.5 m
Added length to account for other factors such as an
C
(11/2 ft)
improperly adjusted harness, actual worker height
or worker weight
Sub-Total Minimum Required Fall Clearance
2.2 m
D
for direct overhead use of SRD with No Swing Fall;
(7 ft)
sum of A, B and C only
*Additional Fall Clearance Calculation
E
due to Swing Fall (using Chart 1)
Total Required Fall Clearance
F
Including sub-total D and Swing Fall E (from Chart 1)
1. Overhead Anchorage 2. Walking/Working Surface
3. Nearest Lower Level or Obstruction
If a potential Swing Fall Hazard condition is also present, additional
Fall Clearance is needed in the above calculation; see Chart 1 for
calculating this additional required distance.
022120
7
Publicité
Chapitres
Table des Matières
